java classes methods and objects explained code example

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

class Number {
    	
    	int number;
    	
    	// square numbers
    	public boolean isSquare(){
    		
    		double squareRoot = Math.sqrt(number);
    		
    		
    		if(squareRoot == Math.floor(squareRoot))
    		{
    			return true;
    		} else {
    			return false;
    		}
    		
    	}
    	
    	// triangular numbers
    	public boolean isTriangular(){
    		
    		int x = 1;
    		
    		int triangularNumber = 1;
    		
    		while(triangularNumber < number){
    			
    			x++;
    			triangularNumber = triangularNumber + x;
    			
    		}
    		
    		if(triangularNumber == number){
    			return true;
    		} else {
    			return false;
    		}
    	}
    }
    
    // testing 
    Number myNumber = new Number();
    myNumber.number = 16;
    
    System.out.println(myNumber.isSquare());