class object and method example in java

Example 1: java classes and methods

import java.lang.Math;
import java.util.Scanner;

public class HelloWorld {
  public static void main(String[] args) {
    class ResultNumberShape {

            double number;

            public boolean isSquare(double number) {

                double result = Math.sqrt(number);
                return ((result - Math.floor(result)) == 0);

            }
        }

        ResultNumberShape checkNumber = new ResultNumberShape();

        System.out.println("Enter any number:");
        Scanner scanner = new Scanner(System.in);
        double num = scanner.nextDouble();

        scanner.close();

        if (checkNumber.isSquare(num)) {
            System.out.println(num + " is a sqaure number!");
        } else {
            System.out.println(num + " is not a square!");
        }
    
  }
}

Example 2: using class in java

public class HelloWorld {
  public static void main(String[] args) {
    
    // how to use class in java
    class User{
    	
    	int score;
    }
    
    User dave = new User();
    
    dave.score = 20;
    
    System.out.println(dave.score);
    
 
  }
}

Example 3: using class in java

public class HelloWorld {
  public static void main(String[] args) {
    
    // how to use class in java
    class User{
    	
    	int score;
    	
    	// method that can be used outside the class
    	public boolean hasWon(){
    		if(score >= 100){
    			return true;
    		} else {
    			return false;
    		}
    	}
    }
    
    User dave = new User();
    
    dave.score = 20;
    
    System.out.println(dave.hasWon());
    
 
  }
}