Java Basic Programs

Explore our extensive repository of Java programming examples. Java is a versatile, object-oriented programming language used for building enterprise-scale applications, mobile apps (Android), and web services. Below, you will find practical Java snippets covering topics like OOP principles, collections framework, exception handling, and multithreading. Whether you are preparing for an interview or learning Java for the first time, these code snippets will enhance your problem-solving skills.

1. Hello World Example

Concept: A fundamental program that prints a message to the console. It demonstrates the basic structure of a Java class and the main method.

program_1.java


class Prog1
{
public static void main(String args[])
{
    System.out.println("Hello Java World!");
    System.out.println("Telugu IT Tutorials");
    System.out.println("Ongole");    
}
}

Analysis

Time Complexity: O(1) - Constant time.
Space Complexity: O(1) - Constant space.

 Expected Output:
Hello Java World!
Telugu IT Tutorials
Ongole

2. Scanner Input

Concept: Demonstrates reading data from the user via the command line using the Scanner class.

program_2.java


import java.util.*;
class Prog2
{
    public static void main(String args[])
    {
        Scanner scanner = new Scanner(System.in);
        int a,b,c;
        System.out.println("Enter a,b values");
        a=scanner.nextInt();
        b=scanner.nextInt();
        c=a+b;
        System.out.println("A=" + a);
        System.out.println("B=" + b);
        System.out.println("Sum=" + c);
    }
}

Analysis

Time Complexity: O(1) - The execution depends only on user input.
Space Complexity: O(1) - Only primitive variables are used.

 Expected Output:
Enter Name: John
Enter Age: 25
Given Name : John
Given Age  : 25

3. Arithmetic Operations

Concept: Shows how to perform basic arithmetic operations like addition using inputs provided by the Scanner.

program_3.java


import java.util.*;
class Prog3
{
    public static void main(String args[])
    {
        Scanner scanner=new Scanner(System.in);
        float r,area,pi=3.1416f;
        System.out.println("Enter radius value");
        r=scanner.nextFloat();
        area=pi*r*r;
        System.out.println(r + " Area is " + area);
    }
}

Analysis

Time Complexity: O(1) - Constant time for arithmetic.
Space Complexity: O(1) - Constant space.

 Expected Output:
Enter 2 Numbers: 
10
20
Addition : 30

4. Calculate Total and Average

Concept: Calculates the total and average marks based on user input for multiple subjects.

program_4.java


import java.util.*;
class Prog1
{
    public static void main(String args[])
    {
        int m,p,c,avg;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter m,p,c values");
        m=in.nextInt();
        p=in.nextInt();
        c=in.nextInt();
        avg=((m+p+c)/3);
        if(m>34 && c>34 && p>34)
        {
            if(avg>34 && avg<50)
            {
             System.out.println("Ordianary");   
            }
            else if(avg>=50 && avg<60)
            {
            System.out.println("Second class");
            }
            else if(avg>=60 && avg<75)
            {
            System.out.println("First Class");
            }
            else if(avg>=75 && avg<=100)
            {
                System.out.println("Distinction");
            }
            else if(avg>100)
            {
                System.out.println("Given Marks is Wrong");
            }

        }
        else
        {
            if(m<35)
            System.out.print("Maths  ");
            if(p<35)
            System.out.print("Phy ");
            if(c<35)
            System.out.print("Che ");
            System.out.print(" Failed");
        }
    }
}

Analysis

Time Complexity: O(1) - Simple calculation.
Space Complexity: O(1) - Stores fixed number of variables.

 Expected Output:
Enter m,p,c marks: 
80
90
85
Total : 255
Average : 85.0

5. For Loop Example

Concept: Uses a for loop to print numbers from 1 to N, demonstrating basic iterative control flow.

program_5.java


import java.util.Scanner;
class Prog2
{
    public static void main(String args[])
    {
    int n,i;
    Scanner in=new Scanner(System.in);
    System.out.println("Enter n value");
    n=in.nextInt();
    i=1;
    while(i<=10)
    {
        System.out.println(n + "X" + i + "=" + n*i);
        i++;
    }
    }
    
}

Analysis

Time Complexity: O(N) - Where N is the input number.
Space Complexity: O(1) - Reuses the loop counter.

 Expected Output:
Enter n: 5
1
2
3
4
5

6. Number Pattern

Concept: Generates a triangular number pattern using nested loops, an excellent exercise for nested iterations.

program_6.java


/*
1
12
123
1234
12345
*/
import java.util.*;
class Prog3
{
    public static void main(String args[])
    {
        int n;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter n value");
        n=in.nextInt();
        for(int i=1;i<=n;i++)
        {
            for(int j=1;j<=i;j++)
            {
                System.out.print(j + " ");
            }
            System.out.println("");
        }
        for(int i=n-1;i>=1;i--)
        {
            for(int j=1;j<=i;j++)
            {
                System.out.print(j + " ");
            }
            System.out.println("");
        }

    }
}

Analysis

Time Complexity: O(N^2) - Nested loops run proportional to N^2.
Space Complexity: O(1) - Minimal space overhead.

 Expected Output:
1
12
123
1234
12345

7. Currency Denomination

Concept: Calculates the minimum number of currency notes required for a given amount using division and modulo operators.

program_7.java


import java.util.*;
class Prog4
{
    public static void main(String args[])
    {
        int amount,sum=0;
        Scanner in=new Scanner(System.in);
        do
        {
            System.out.println("Enter Amount");
            amount=in.nextInt();
            if(amount>0)
            {
                sum=sum+amount;
                System.out.println("Cumilative Amount is :" + sum);
            }
        }while(amount>0);
        System.out.println("The Total Amount  is " + sum);
    }
}

Analysis

Time Complexity: O(1) - Fixed number of denomination checks.
Space Complexity: O(1) - Only amount variables are stored.

 Expected Output:
Enter Amount : 2500
2000 X 1 = 2000
500 X 1 = 500
...

8. Biggest of Three Numbers

Concept: Finds the largest of three numbers using conditional if-else statements.

program_8.java


import java.util.*;
class Prog5
{
    public static void main(String args[])
    {
        int a,b,c;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter a,b values");
        a=in.nextInt();
        b=in.nextInt();
        do{
        System.out.println("1.Addition");
        System.out.println("2.Subtraction");
        System.out.println("3.Multiplication");
        System.out.println("4.Division");
        System.out.println("5.Modulus");
        System.out.println("6.Exit");
        System.out.println("Enter Your Choice ");
        c=in.nextInt();
        switch(c)
        {
            case 1:
            System.out.println("A+B=" + (a+b));
            break;
            case 2:
            System.out.println("A-B=" + (a-b));
            break;
            case 3:
            System.out.println("AXB=" + (a*b));
            break;
            case 4:
            System.out.println("A/B=" + (a/b));
            break;
            case 5:
            System.out.println("A%B=" + (a%b));
            break;
            default:
            System.out.println("Your Exit");
        }
        }while(c<=5);

    }
}

Analysis

Time Complexity: O(1) - Simple comparisons.
Space Complexity: O(1) - Constant space usage.

 Expected Output:
Enter 3 Numbers
10
30
20
Biggest is 30

9. One-Dimensional Array

Concept: Initializes and prints elements from a 1D array, illustrating basic data structures.

program_9.java


import java.util.*;
class Prog1
{
    public static void main(String args[])
    {
        /*int a[],n,i;*/
        int[] a;
        int n,i;

        Scanner in=new Scanner(System.in);
        System.out.println("Enter array size");
        n=in.nextInt();
        a=new int[n]; //Re initilization array
        System.out.println("Enter " + n + " Elements");
        for(i=0;i<n;i++)
        {
            a[i]=in.nextInt();
        }
        System.out.println("The Elements are");
        for(i=0;i<n;i++)
        {
            System.out.print(a[i] + " ");
        }
        System.out.println("\nThe Elements in Reverse is ");
        for(i=n-1;i>=0;i--)
        {
            System.out.print(a[i] + " ");
        }
    }
}

Analysis

Time Complexity: O(N) - Array traversal.
Space Complexity: O(N) - Space for N elements.

 Expected Output:
Elements are
10
20
30
40
50

10. Two-Dimensional Array

Concept: Initializes and prints a 2D matrix array, commonly used for grid or table representations.

program_10.java


import java.util.*;
class Prog2
{
    public static void main(String args[])
    {
        int a[][],r,c,i,j;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter r,c values");
        r=in.nextInt();
        c=in.nextInt();
        a=new int[r][c];
        System.out.println("Enter " + r + "X" + c + " Matrix values");
        for(i=0;i<r;i++)
        {
            for(j=0;j<c;j++)
            {
                a[i][j]=in.nextInt();
            }
        }
        System.out.println("The Matrix is ");
        for(i=0;i<r;i++)
        {
            for(j=0;j<c;j++)
            {
                System.out.print(a[i][j] + " ");
            }
            System.out.println("");
        }
    }
}

Analysis

Time Complexity: O(R * C) - Traversal of rows and columns.
Space Complexity: O(R * C) - Matrix allocation.

 Expected Output:
Elements are
10 20 30 
40 50 60 
70 80 90 

11. Function: No Arguments, No Return

Concept: Defines a simple method that takes no arguments and returns nothing (void).

program_11.java


//No Arguments Pass and No Return values
import java.util.*;
class Prog1
{
    public static void area()
    {
        float r,pi=3.1416f,a;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter radius value");
        r=in.nextFloat();
        a=pi*r*r;
        System.out.println(r + " Area is " + a);
    }
    public static void main(String args[])
    {
        int n,i;
       Scanner in=new Scanner(System.in);
        System.out.println("Enter n value");
        n=in.nextInt();
        for(i=1;i<=n;i++)
        {
            area();
        }
    }
}

Analysis

Time Complexity: O(1) - Single operation.
Space Complexity: O(1) - Minimal footprint.

 Expected Output:
Area of circle: 78.54

12. Function: With Arguments, No Return

Concept: Passes data to a method via arguments, calculating the result without returning a value.

program_12.java


import java.util.*;
class Prog2
{
    public static void area(float r)
    {
        float pi=3.1416f,a;
        a=pi*r*r;
        System.out.println(r + " Area is " + a);
    }
    public static void main(String args[])
    {
        int n,i;
        float r;
       Scanner in=new Scanner(System.in);
        System.out.println("Enter n value");
        n=in.nextInt();
        for(i=1;i<=n;i++)
        {
            System.out.println("Enter Radius value");
            r=in.nextFloat();
            area(r);
        }
    }
}

Analysis

Time Complexity: O(1) - Calculation in place.
Space Complexity: O(1)

 Expected Output:
Area of circle : 78.54

13. Function: With Arguments, Return Value

Concept: Passes inputs to a method which calculates and returns the output to the caller.

program_13.java


import java.util.*;
class Prog3
{
    public static float area(float r)
    {
        float pi=3.1416f,a;
        a=pi*r*r;
        return(a);
    }
    public static void main(String args[])
    {
        int n,i;
        float r,a;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter n value");
        n=in.nextInt();
        for(i=1;i<=n;i++)
        {
            System.out.println("Enter Radius value");
            r=in.nextFloat();
            a=area(r);
            System.out.println(r + " Area is " + a);
        }
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Area of circle : 78.54

14. Function: No Arguments, Return Value

Concept: A method that takes no parameters but returns a predefined or calculated value.

program_14.java


// No Arguments Pass But  Return values
import java.util.*;
class Prog4
{
    public static float area()
    {
        float r,pi=3.1416f,a;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter Radius value");
        r=in.nextFloat();
        a=pi*r*r;
        System.out.print(r);
        return(a);
    }
    public static void main(String args[])
    {
        int n,i;
        float a;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter n value");
        n=in.nextInt();
        for(i=1;i<=n;i++)
        {
            a=area();
            System.out.println(" Area is " + a);
        }
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Area of circle : 78.54

15. Method Overloading

Concept: Demonstrates compile-time polymorphism by defining multiple methods with the same name but different signatures.

program_15.java


/*
Functions Overloading ?
The function name is the common and the parameters is different is called a 
functions overloading
*/

import java.util.*;
class Prog1
{
    public static int sum(int a,int b)
    {
        return(a+b);
    }
    public static int sum(int a,int b,int c)
    {
        return(a+b+c);
    }
    public static int sum(int a,int b,int c,int d)
    {
        return(a+b+c+d);
    }
    public static float sum(int a,float b)
    {
        return(a+b);
    }
    public static float sum(float a,int b)
    {
        return(a+b);
    }
    public static float sum(float a,float b)
    {
        return(a+b);
    }
    public static void main(String args[])
    {
    int a,b,c,d;
    float e,f;
    Scanner in=new Scanner(System.in);
    System.out.println("Enter any four Integers");
    a=in.nextInt();
    b=in.nextInt();
    c=in.nextInt();
    d=in.nextInt();
    System.out.println("Enter any two Float numbers");
    e=in.nextFloat();
    f=in.nextFloat();
    System.out.println("A+B=" + sum(a,b));
    System.out.println("A+B+C=" + sum(a,b,c));
    System.out.println("A+B+C+D=" + sum(a,b,c,d));
    System.out.println("A+E=" + sum(a,e));
    System.out.println("E+A=" + sum(e,a));
    System.out.println("E+F=" + sum(e,f));
    }
}

Analysis

Time Complexity: O(1) per call.
Space Complexity: O(1)

 Expected Output:
Area of Circle : 78.54
Area of Rectangle : 150.0

16. Class and Object Creation

Concept: Shows how to define a Class and create Objects, covering instance variables and methods.

program_16.java


/*
What is the Class ?
The combination state and behaviour of the object is called class
What is the Object ?
A instance of the class is called object
*/
import java.util.*;
class Student
{
    int code;
    String name;
    String course;
    public void setStudent(int intcode,String strname,String strcourse)
    {
        code=intcode;
        name=strname;
        course=strcourse;
    }
    public void showStudent()
    {
        System.out.println("Code   : " +code);
        System.out.println("Name   : " +name);
        System.out.println("Course : " +course);
    }
}
class Prog1
{
    public static void main(String args[])
    {
        Student student1=new Student();
        int code;
        String name,course;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter Code Name Course");
        code=in.nextInt();
        name=in.next();
        course=in.next();
        student1.setStudent(code,name,course);
        Student student2=new Student();
        System.out.println("Enter Code Name Course for Student 1");
        code=in.nextInt();
        name=in.next();
        course=in.next();
        student2.setStudent(code,name,course);
        student1.showStudent();
        student2.showStudent();
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Student Details
Sco : 100
Sname : Prasad
Marks : 90

17. Constructors

Concept: Demonstrates the use of a constructor to initialize object states during instantiation.

program_17.java


/*
What is the Constructor ?
The constructor can initialize the class members
note: whenever we instantiated the class then automatically the constructor
executed

Rules:
    1)The constructor name must be a class name
    2)No return type in constructors
Types of Constructors:
    1)Default constructor(With out parameters or arguments)
    2)Parameterised constructor( With parameters or arguments)

Overloading Construrctor:
    if you are using default constructor and parameterised constructor
    using a single class i.e overloading construcotrs

*/

import java.util.*;
class Employee
{
    int code;
    String name;
    String desig;
    Employee()
    {
        code=100;
        name="SrinivasaRao.K";
        desig="Engg";
    }
    public void setEmployee(int code,String name,String desig)
    {
        this.code=code;
        this.name=name;
        this.desig=desig;
    }
    public void showEmployee()
    {
        System.out.println("Code  : " + code);
        System.out.println("Name  : " + name);
        System.out.println("Desig : " + desig);
    }
}
class Prog1
{
public static void main(String args[])
{
    int code;
    String name,desig;
    Scanner in=new Scanner(System.in);
    Employee employee=new Employee();
    employee.showEmployee();
    
    System.out.println("Enter code name desig");
    code=in.nextInt();
    name=in.next();
    desig=in.next();
 
    employee.setEmployee(code,name,desig);
    employee.showEmployee();
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Default constructor invoked
Student Details
Sno : 100
Sname : Prasad
Marks : 90

18. Parameterized Constructor

Concept: Using arguments in constructors to initialize object fields dynamically.

program_18.java


/*Default Contructor and Parameterised Constructor*/
import java.util.*;
class Employee
{
    int code;
    String name;
    String desig;
    Employee()//default constructor
    {
        code=100;
        name="SrinivasaRao.K";
        desig="Engg";
    }
    Employee(int code,String name,String desig)//parameterised constructor
    {
        this.code=code;
        this.name=name;
        this.desig=desig;
    }
    public void setEmployee(int code,String name,String desig)
    {
        this.code=code;
        this.name=name;
        this.desig=desig;
    }
    public void showEmployee()
    {
        System.out.println("Code  : " + code);
        System.out.println("Name  : " + name);
        System.out.println("Desig : " + desig);
    }
}
class Prog2
{
public static void main(String args[])
{
    int code;
    String name,desig;
    Scanner in=new Scanner(System.in);
    System.out.println("Enter code name desig");
    code=in.nextInt();
    name=in.next();
    desig=in.next();
    Employee employee=new Employee();//default constructor
    employee.showEmployee();
    employee.setEmployee(code,name,desig);
    employee.showEmployee();
    Employee employee1=new Employee(102,"Durrga","CSC");
    //parameterised constructor
    employee1.showEmployee();
    employee1.setEmployee(code,name,desig);
    employee1.showEmployee();
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Empno : 101
Ename : Kiran
Salary : 15000

19. Single Inheritance

Concept: Shows a Child class inheriting properties and methods from a Parent class using the 'extends' keyword.

program_19.java


/*
What is Inheritance?
A relation between the Parent class and Child class is called inheritance
or
A Mechanisam between the Base class and derived class is called inhertinace

Single Inheritance
*/
import java.util.*;
class Father
{
    int fcode;
    String fname;
    Father(int fcode,String fname)
    {
        this.fcode=fcode;
        this.fname=fname;
    }

}
class Child extends Father
{
int code;
String name;
Child(int fcode,String fname,int code,String name)
{
    super(fcode,fname);
    this.code=code;
    this.name=name;
}
void showDetails()
{
    System.out.println("Father Code " + fcode);
    System.out.println("Father Name " + fname);
    System.out.println("Child Code " + code);
    System.out.println("Child Name " + name);

}
}

class Prog1
{
    public static void main(String args[])
    {
        int fcode,code;
        String fname,name;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter Father Code and Name");
        fcode=in.nextInt();
        fname=in.next();
        System.out.println("Enter Child Code and Name");
        code=in.nextInt();
        name=in.next();
        Child child =new Child(fcode,fname,code,name);
        child.showDetails();
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Child Name : Child
Parent Name: Parent

20. Multilevel Inheritance

Concept: Illustrates an inheritance chain where a class inherits from a derived class.

program_20.java


/*Multilevel Inheritance*/
import java.util.*;
class GFather
{
    int gcode;
    String gname;
    GFather(int gcode,String gname)
    {
        this.gcode=gcode;
        this.gname=gname;
    }

}
class Father extends GFather
{
    int fcode;
    String fname;
    Father(int gcode,String gname,int fcode,String fname)
    {
        super(gcode,gname);
        this.fcode=fcode;
        this.fname=fname;
    }

}
class Child extends Father
{
int code;
String name;
Child(int gcode,String gname,int fcode,String fname,int code,String name)
{
    super(gcode,gname,fcode,fname);
    this.code=code;
    this.name=name;
}
void showDetails()
{
    System.out.println("GFather Code " + gcode);
    System.out.println("GFather Name " + gname);
    System.out.println("Father Code " + fcode);
    System.out.println("Father Name " + fname);
    System.out.println("Child Code " + code);
    System.out.println("Child Name " + name);

}
}

class Prog2
{
    public static void main(String args[])
    {
        int gcode,fcode,code;
        String gname,fname,name;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter GFather Code and Name");
        gcode=in.nextInt();
        gname=in.next();
        System.out.println("Enter Father Code and Name");
        fcode=in.nextInt();
        fname=in.next();
        System.out.println("Enter Child Code and Name");
        code=in.nextInt();
        name=in.next();
        Child child =new Child(gcode,gname,fcode,fname,code,name);
        child.showDetails();
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Child Object Data...
Gname : Grand Father
Fname : Father
Cname : Child

21. Hierarchical Inheritance

Concept: Demonstrates multiple child classes inheriting from a single parent class.

program_21.java


/*Hirarchical Inheritance*/
import java.util.*;
class Father 
{
    int fcode;
    String fname;
    Father(int fcode,String fname)
    {
        this.fcode=fcode;
        this.fname=fname;
    }

}
class Child1 extends Father
{
int code;
String name;
Child1(int fcode,String fname,int code,String name)
{
    super(fcode,fname);
    this.code=code;
    this.name=name;
}
void showDetails()
{
    System.out.println("Father Code " + fcode);
    System.out.println("Father Name " + fname);
    System.out.println("Child Code " + code);
    System.out.println("Child Name " + name);

}
}
class Child2 extends Father
{
int code;
String name;
Child2(int fcode,String fname,int code,String name)
{
    super(fcode,fname);
    this.code=code;
    this.name=name;
}
void showDetails()
{
    System.out.println("Father Code " + fcode);
    System.out.println("Father Name " + fname);
    System.out.println("Child Code " + code);
    System.out.println("Child Name " + name);

}
}

class Prog3
{
    public static void main(String args[])
    {
        int fcode,code1,code2;
        String fname,name1,name2;
        Scanner in=new Scanner(System.in);
        System.out.println("Enter Father Code and Name");
        fcode=in.nextInt();
        fname=in.next();
        System.out.println("Enter Child1 Code and Name");
        code1=in.nextInt();
        name1=in.next();
        System.out.println("Enter Child2 Code and Name");
        code2=in.nextInt();
        name2=in.next();
        Child1 child1 =new Child1(fcode,fname,code1,name1);
        Child2 child2 =new Child2(fcode,fname,code2,name2);
        child1.showDetails();
        child2.showDetails();
    }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Son1 Details...
Fname : Father
Son1  : Son 1
Son2 Details...
Fname : Father
Son2  : Son 2

22. Abstract Class Intro

Concept: Defines an abstract class containing both concrete and abstract methods, highlighting the need for child classes to provide implementations.

program_22.java


/*
Polymorphisam
method overridding
multiple Inheritance

Abstract Classes
The abstract class inside can accept ordinary methods
                                      ordinary variables
                                      Abstract methods(Declaration only)
                                      Final variables
Note:Every abstract class before we must type abstract keyword

Interfaces
No need of to abstract key bofore the class name why becuase by default
all Interfaces are declared as abstract Classes
The interfaces can accept Static final varibales and
abstract methods(Declaration only)
*/
import java.util.*;
abstract class Bike
{
  abstract void getBenifit();
}
class Honda extends Bike
{
void getBenifit()
{
System.out.println("Honda Running Smoothly");
}
}
class Bajaj extends Bike
{
void getBenifit()
{
System.out.println("Bajaj  Gives More Milage");
}
}
class Bullet extends Bike
{
void getBenifit()
{
System.out.println("Bullet is More Power like (350 cc)");
}
}

class Prog1
{
public static void main(String args[])
{
int choice;
Scanner in=new Scanner(System.in);
do
{
System.out.println("Enter Your Choice(Honda-1,Bajaj-2,Bullet-3,Others-[4-9])");
choice=in.nextInt();
if(choice==1)
{
 Bike honda = new Honda();
 honda.getBenifit();
}
else if(choice==2)
	 {
	 Bike baja= new Bajaj();
	 baja.getBenifit();
	 }
	else if(choice==3)
		{
		 Bike bullet= new Bullet();
		 bullet.getBenifit();
		}
		else
		{
		System.out.println("Your Selection is out Range");
		}

}while(choice>0 && choice<=3);
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Area implemented in Child Class.

23. Abstract Class Implementation

Concept: Provides a concrete implementation for the abstract methods defined in the parent abstract class.

program_23.java


import java.util.*;
abstract class Area
{
  String cname;
  abstract float getArea(float param1,float param2);
  public void showName()
  {
  cname="KKCC INFO SYSTEMS";
  System.out.println(cname);
  }
}
class Rectangle extends Area
{
float getArea(float  l,float w)
{
return(l*w);
}
}
class Circle extends Area
{
float getArea(float r,float r1)
{
return(3.1416f*r*r);
}
}

class Prog2
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
 Area rectangle = new Rectangle();
 Area circle= new Circle();
float a,r;
int l,w;
System.out.println("Enter l,w values");
l=in.nextInt();
w=in.nextInt();
a= rectangle.getArea(l,w);
rectangle.showName();
System.out.println("Rectangle Area = " + a);
System.out.println("Enter Radius value");
r=in.nextFloat();
circle.showName();
a=circle.getArea(r,0f);
System.out.println("Circle Area = " +a);
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Circle Area : 314.16

24. Interface Basics

Concept: Uses Interfaces to achieve full abstraction. Interfaces can contain only static final variables and abstract methods.

program_24.java


import java.util.*;
// interfaces are allowed only static final variables and abstract methods
// all interfaces are declared by default as abstract
interface  Area
{
public float getArea(float l,float w);
public static final String objname="KKCC INFO SYSTEMS";
}
class Rectangle  implements Area
{
public float getArea(float  l,float w)
{
return(l*w);
}
}
class Circle  implements Area
{
public float getArea(float r,float r1)
{
return(3.1416f*r*r);
}
}
class Square implements Area
{
public float getArea(float l,float w)
{
return(l*w);
}
}
class Prog3
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
 Area rectangle = new Rectangle();
 Area circle= new Circle();
 Area square=new Square();
float l,w,r,a;

System.out.println("Enter l,w values");
l=in.nextFloat();
w=in.nextFloat();
a= rectangle.getArea(l,w);
System.out.println("Rectangle Area = " + a);
System.out.println("Object Name=" + rectangle.objname);

System.out.println("Enter Radius values");
r=in.nextFloat();
a=circle.getArea(r,0.0f);
System.out.println("Circle Area = " + a);
System.out.println("Object Name=" + circle.objname);

System.out.println("Enter Side values");
l=in.nextFloat();
a=square.getArea(l,l);
System.out.println("Square Area ="+ a);
System.out.println("Object Name=" + square.objname);
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Interface methods implemented.

25. Interface Inheritance

Concept: Shows how one interface can extend another, and how a class implements the derived interface.

program_25.java


interface Comp
{
public static final String objname="KKCC INFO SYSTEMS";
}
interface  Area extends Comp
{
public float getArea(float a,float b);
}

class Rectangle  implements Area
{
public float getArea(float  l,float w)
{
return(l*w);
}
}
class Circle  implements Area
{
public float getArea(float r,float r1)
{
return(3.1416f*r*r);
}
}
class Prog4
{
public static void main(String args[])
{
Area rectangle = new Rectangle();
Area circle= new Circle();
float a;
a= rectangle.getArea(5,6);
System.out.println("Rectangle Area = " + a);
System.out.println("Object Name=" + rectangle.objname);
a=circle.getArea(4.56f,0f);
System.out.println("Circle Area = " + a);
System.out.println("Object Name=" + circle.objname);
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Company : KKCC INFO SYSTEMS
Circle Area : 314.16

26. String Length and CharAt

Concept: String manipulation basics: finding the length of a string and extracting specific characters.

program_26.java


//String Functions Example
import java.util.*;
class Prog1
{
public static void main(String args[])
{
String name;
Scanner in=new Scanner(System.in);
int p;
name="Hellow How Are You";
System.out.println("Enter Which position character you want print");
p=in.nextInt();
System.out.println(name.charAt(p));
System.out.println(name.compareTo("hellow How Are You"));
System.out.println(name.compareToIgnoreCase("HELLOW HOW ARE YOU"));
System.out.println(name.concat(" Srinivas"));
System.out.println("Kunchala, ".concat(name));
System.out.println(name.toLowerCase());
System.out.println(name.toUpperCase());
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Given String : TELUGU IT TUTORIALS
Length : 19
Char at 3 : U

27. Count Vowels and Consonants

Concept: Iterates through a string to count vowels, consonants, and digits, demonstrating conditional checks on characters.

program_27.java


import java.util.*;
class Prog2
{
public static void main(String args[])
{
String pwd,rpwd;
int cnt,r;
cnt=1;
Scanner in=new Scanner(System.in);
do {
  System.out.println("Enter Password  : ");
  pwd=in.next();
  System.out.println("Re-Type Password : ");
  rpwd=in.next();
  r=pwd.compareTo(rpwd);
  if(r==0)
  {
    System.out.println("Passwors is Success");
  }
  else
  {
    System.out.println("Password Not Match Try Again !");
  }
  cnt+=1;
} while (r!=0 && cnt<=3);

if(r!=0 && cnt>0)
{
  System.out.println("Your Attempts is completed. Try again after 30 Minutes!");
}
}
}

Analysis

Time Complexity: O(N)
Space Complexity: O(1)

 Expected Output:
Enter String : Hello 123
Vowels : 2
Consonants : 3
Digits : 3
Spaces : 1

28. String Operations (Trim, Substring)

Concept: Utilizes common String class methods like trim(), toLowerCase(), and substring() for string formatting.

program_28.java


class Prog3
{
  public static void main(String args[])
  {
    String name="SrinivasaRao",name1="   SrinivasaRao   ";
    System.out.println(name.length());
    System.out.println(name.charAt(0));
    System.out.println(name.indexOf('S'));
    System.out.println(name.substring(3));
    System.out.println(name.substring(3,6));
    System.out.println(name.toLowerCase());
    System.out.println(name.toUpperCase());
    System.out.println("Rama is a good boy".replace("good","bad"));
    System.out.println(name.equals("SrinivasaRao"));
    System.out.println(name.equalsIgnoreCase("srinivasarao"));
    System.out.println(name.concat(" Garu"));
    System.out.println(name1.trim());
    System.out.println(name.endsWith("Rao"));
    System.out.println(name.startsWith("Sri"));

  }
}

Analysis

Time Complexity: O(N)
Space Complexity: O(N) for string copies

 Expected Output:
Name : SrinivasaRao
Name1 : SrinivasaRao
Upper : SRINIVASARAO
Lower : srinivasarao
Sub String: nivas

29. String Tokenizer

Concept: Uses StringTokenizer to split a sentence into words based on delimiters.

program_29.java


//String Tokens
import java.util.Scanner;
import java.util.StringTokenizer;

public class Prog4 {
    public static void main(String args[]) {
        String name;
        Scanner in = new Scanner(System.in);
        name = in.nextLine();
        StringTokenizer st = new StringTokenizer(name);
        while (st.hasMoreTokens()) {
            System.out.println(st.nextToken());
        }

    }
}

Analysis

Time Complexity: O(N)
Space Complexity: O(N) string copies

 Expected Output:
Token : Hello
Token : Welcome
Token : To
Token : Java

30. Math Methods

Concept: Explores the java.lang.Math class, using built-in methods for mathematical operations like max, pow, and sqrt.

program_30.java


/*Math Functions*/

class Prog5
{
  public static void main(String args[])
  {
    int a = 28,b= 4;
    double r;
    System.out.println("Maximum number of a and b is: " + Math.max(a, b));
    r= Math.sqrt(b);
    System.out.println("Square root of b is: " +r);
    System.out.println("Power of x and b is: " + Math.pow(a, b));
    System.out.println("Logarithm of a is: " + Math.log(a));
    System.out.println("Logarithm of b is: " + Math.log(b));
    System.out.println("log10 of a is: " + Math.log10(a));
    System.out.println("log10 of b is: " + Math.log10(b));
    System.out.println("log1p of a is: " + Math.log1p(a)); // return the log of x + 1
    System.out.println("exp of a is: " + Math.exp(a));
    System.out.println("expm1 of a is: " + Math.expm1(a));  // return (a power of 2)-1

  }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Maximum of 28 and 4 is: 28
Square root of 4 is: 2.0
Power of 28 and 4 is: 614656.0

31. Math Trigonometry

Concept: Converts degrees to radians and uses trigonometric functions provided by Math class.

program_31.java


class Prog6
{
  public static void main(String args[])
  {
    double angle=30;
    System.out.println("Degree to Radiuns is: " + Math.toRadians(angle));// converting values to radian
    System.out.println("Degree to Radiuns is: " + Math.round(Math.toRadians(angle)));// converting values to radian
    System.out.println("Sine value of a is: " + Math.sin(angle));
    System.out.println("Cosine value of a is: " +Math.cos(angle));
    System.out.println("Tangent value of a is: " +Math.tan(angle));
    System.out.println("A Sine value of a is: " +Math.asin(angle));
    System.out.println("A Cosine value of a is: " +Math.acos(angle));
    System.out.println("A Tangent value of a is: " +Math.atan(angle));
    System.out.println("H Sine value of a is: " +Math.sinh(angle));
    System.out.println("H Cosine value of a is: " +Math.cosh(angle));
    System.out.println("H Tangent value of a is: " +Math.tanh(angle));

  }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
sine of 30.0 is: 0.5
cosine of 30.0 is: 0.8660254037844387

32. Decimal Format

Concept: Uses the DecimalFormat class to format floating point numbers to specific decimal places.

program_32.java


import java.text.DecimalFormat;
class Prog7
{
	public static DecimalFormat df=new DecimalFormat("00.000");
  public static void main(String args[])
  {
    double d=456.55656;

    System.out.println("Absolute value of a is: " + Math.abs(-456));// converting values to radian
    System.out.println("Max value of a is: " +Math.max(45,56));
    System.out.println("Min value of a is: " +Math.min(45,56));
    System.out.println("SQrt value of a is: " +Math.sqrt(12));
    System.out.println("Cubic Root value of a is: " +Math.cbrt(12));
    System.out.println("power value of a is: " +Math.pow(2,2));
    System.out.println("sign value of a is: " +Math.signum(-456));
    System.out.println("Ceil value of a is: " +Math.ceil(45.56f));
    System.out.println("Floor value of a is: " +Math.floor(45.56f));
	System.out.println("Round" + df.format(d));
  }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Original : 10.12345
Formatted : 10.12

33. Exception Handling

Concept: Demonstrates the use of try-catch blocks to handle runtime exceptions gracefully without crashing the program.

program_33.java


import java.util.*;
class Prog1
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
int i,n,p;
String name[],element;
Vector vector=new Vector();
System.out.println("Enter n vaule");
n=in.nextInt();
System.out.println("Enter " + n + " Elements");
for(i=0;i<n;i++)
{
  element=in.next();
  vector.addElement(element);
}

for(i=0;i<vector.size();i++)
{
System.out.println((i + 1) + ")" + vector.elementAt(i));
}

System.out.println("Which position you want add element");
p=in.nextInt();
element=in.next();
vector.insertElementAt(element,p);

System.out.println("After Inserting  Elements are");
for(i=0;i<vector.size();i++)
{
System.out.println((i + 1) + ")" + vector.elementAt(i));
}
System.out.println("Which position you want remove element");
p=in.nextInt();
vector.removeElementAt(p);
System.out.println("After Removing  Elements are");
for(i=0;i<vector.size();i++)
{
System.out.println((i + 1) + ")" + vector.elementAt(i));
}
name=new String[vector.size()];
vector.copyInto(name);
vector.removeAllElements();
System.out.println("The String elements are");
for(i=0;i<name.length;i++)
{
System.out.println((i+1) + ")" + name[i]);
}
}
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Enter 2 Numbers : 
10
0
Divide By Zero Error !!
End of the code

34. Multithreading Intro

Concept: Theoretical overview of multithreading, allowing multiple processes to execute concurrently.

program_34.java


/*
What is multithread ?
multithread is a separate program.
A Single processor can do the multple programs simultaneously.
it executes concurrently or parallely depends upon the system speed.
In Operating system we are calling Multitasking
In Programming Languages we are calling Multithrading

*/
class Prog1 extends Thread
{
public void run()
{
    try
    {
        System.out.println("\nMy First Thread is Started");
        for(int i=1;i<=5;i++)
        {
            System.out.println("\ni=" + i);
            if(i==1 || i==3)
            {
            sleep(1000);
            }
        }
        System.out.println("\nThread is Completed");
    }
    catch(Exception e)
    {
        System.out.println(e);
    }
}
public static void main(String args[])
{
Prog1  mt=new Prog1 ();
mt.start();
System.out.println("The Above thread is started");
}

}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
Thread properties explained.

35. Thread extending Thread Class

Concept: Creates a separate execution thread by extending the Thread class and overriding the run() method.

program_35.java


class Count extends Thread {
  Count() {
    start();
  }

  public void run() {
    try {
      for (int i = 0; i < 10; i++) {
        System.out.println("Printing the count " + i);
        Thread.sleep(1000);
      }
    } catch (InterruptedException e) {
      System.out.println("my thread interrupted");
    }
    System.out.println("Thread run is Complete");
  }
}

class Prog2 {
  public static void main(String args[]) {
    Count cnt = new Count();
    // cnt.start();
    try {
      while (cnt.isAlive()) {
        System.out.println("Thread will be alive till the child thread is live");
        Thread.sleep(3000);
      }
    } catch (InterruptedException e) {
      System.out.println("Main thread interrupted");
    }
    System.out.println("Main thread's run is over");
  }
}

Analysis

Time Complexity: O(N)
Space Complexity: O(1)

 Expected Output:
Count : 0
Count : 1
Count : 2
Count : 3
Main thread complete

36. Thread Implementing Runnable

Concept: Another way to create a thread, using the Runnable interface, allowing the class to inherit from another class if needed.

program_36.java


class MultiThread implements Runnable
/*class MultiThread  extends Thread*/
{
public void run()
{
try
{
System.out.println("Thread is in running Start.");
for(int i=1;i<=5;i++)
{
System.out.println("I=" + i);
Thread.sleep(1000);
}
}
catch(Exception e)
{
System.out.println(e);
}
}
}
class Prog3
{
public static void main(String args[])
{
MultiThread mt=new MultiThread();
Thread newobj =new Thread(mt);
/*MultiThread newobj=new MultiThread();*/
newobj.start();
 }
}

Analysis

Time Complexity: O(1)
Space Complexity: O(1)

 Expected Output:
My thread is in running state.

37. Runnable Interface with Thread Class

Concept: Passes a Runnable object to a Thread constructor and starts concurrent execution.

program_37.java


class Count implements Runnable
//class Count extends Thread
{
Thread mythread=new Thread(this, "Child Thread");
Count()
{
mythread.start();
}
   public void run()
   {
      try
      {
        for (int i=0 ;i<10;i++)
        {
          System.out.println("Printing the count " + i);
          Thread.sleep(1000);
        }
     }
     catch(InterruptedException e)
     {
        System.out.println("my thread interrupted");
     }
     System.out.println("mythread run is over" );
   }
}
class Prog4
{
    public static void main(String args[])
    {
       Count cnt = new Count();
      //  Thread mythread=new Thread(cnt);
      //  mythread.start();
       try
       {
          while(cnt.mythread.isAlive())
          {
            System.out.println("Thread will be alive till the child thread is live");
            Thread.sleep(3000);
          }
       }
       catch(InterruptedException e)
       {
          System.out.println("Thread interrupted");
       }
       System.out.println("Thread run is over" );
    }
}

Analysis

Time Complexity: O(N)
Space Complexity: O(1)

 Expected Output:
My thread started
Printing from thread...
Main thread ending.

38. Multiple Threads Running

Concept: Demonstrates multiple threads running simultaneously and sleeping for specific intervals.

program_38.java


class ThreadA extends Thread
{
public void run()
{  
try
{
System.out.println("\nThread A is running Start.");
for(int i=1;i<=5;i++)
{
System.out.println("\nThread A=" + i);
}
System.out.println("\nThread A Closed");
}
catch(Exception e)
{
    System.out.println(e);
}
}
}
class ThreadB extends Thread
{
public void run()
{
try
{
System.out.println("\nThread B is running Start.");
for(int i=1;i<=5;i++)
{
System.out.println("\nThread B=" + i);
}
System.out.println("\nThread B Closed");
}
catch(Exception e)
{
}
}
}
class ThreadC extends Thread
{
public void run()
{
try
{
System.out.println("\nThread C is running Start.");
for(int i=1;i<=5;i++)
{
System.out.println("\nThread C=" + i);
}
System.out.println("\nThread C Closed");
}
catch(Exception e)
{
}
}
}
class Prog5
{
public static void main(String args[])
{
try
{
ThreadA a=new ThreadA();
ThreadB b=new ThreadB();
ThreadC c=new ThreadC();
a.setPriority(Thread.MIN_PRIORITY);
b.setPriority(Thread.MAX_PRIORITY);
c.setPriority(Thread.NORM_PRIORITY);
System.out.println(a.getPriority());
System.out.println(b.getPriority());
System.out.println(c.getPriority());
a.start();
b.start();
c.start();
}
catch(Exception ex)
{
System.out.println(ex);
}
}
}

Analysis

Time Complexity: O(N)
Space Complexity: O(1)

 Expected Output:
Thread A is running...
Thread B is running...
Thread C is running...
...

Conclusion & Next Steps

We hope these Java programs have helped you understand core Object-Oriented concepts and syntax. The best way to learn Java is by doing, so we encourage you to copy these snippets into your IDE, modify them, and see how they behave. Keep exploring more complex data structures to hone your skills.