如何在 class 中将方法从第一种方法调用到第二种方法

Question

The number is given and we need to find if it is a square number or triangle number? This "num" should 1st verify the square method then it has to go for triangle method.

there issue is: how can i call from square to triangle or any other methed to call the Triangle method if my square method won't suit.

Here's my code:

public class HelloWorld{

     public static void main(String []args){

        class Number{

            int num;

            public boolean isSquare(){

                int squareNumber=1;

                while(squareNumber<num){

                   squareNumber = num*num;

                }
                if(squareNumber%num==0)
                {
                    System.out.println(num+" is a Square number");
                }
                else
                {
                 return isTriangle();
                }

            boolean isTriangle() {

                int x=1,triangleNumber=1;

                while(triangleNumber<num){

                   x++;

                    triangleNumber = triangleNumber + x;

                }
                if(triangleNumber==num)
                {
                    System.out.println(num+" is a triangle number");
                }
                else
                {
                     System.out.println(num+" is applicable for both triangle and square numbers");
                }
            }
        }
    }
        Number mynum = new Number();
        mynum.num=2;
        System.out.println(mynum.isSquare());
    }
}

Answer 1

So first it would be much easier for you to just do this:

public boolean isSquare(int num){
   ...
}

And so get rid of:

mynum.num = yourNumber;

As very often you will encounter this approach in methods, where the raw input is can be any number/text...

Now for your code, a very good optimization is:

public boolean isSquare(int num){
   if (num>0) //To check if the number is null or not...
      squareNumber = num*num;
}

Because the while loop condition is always met once and then exited after the first entry...

Moving on to the next part... which for me, is very tricky as I see it useless because it always returns true (the text) as the "squareNumber" always has num as root, and will always pass if (squareNumber%num==0) as true, and isTriangle(...) will never be called.

The more approachable way is:

public class HelloWorld {

   static String result;

   public static void main(String[] args) {
       int mynum = 36;
       System.out.print(isSquare(mynum)+isTriangle(mynum));
     }

     public static String isSquare(int num){
       if ((Math.sqrt(num)==(int)Math.sqrt(num))){
         return "Given number is a square";
       } else return "Given number isn't a square,";
     }
     public static String isTriangle(int num){
      if (isSquare(8*num+1)){
        return " but is still a triangular number!";
      } else return " but not a triangular number.";
     }
  }

Answer 2

public static void main(String []args){

        class Number{

            int num;

            public boolean isSquare(){

                int squareNumber=1;

                while(squareNumber<num){

                   squareNumber = num*num;

                }
                if(squareNumber%num==0)
                {
                    System.out.println(num+" is a Square number");
                }


                 return isTriangle();

            }
            boolean isTriangle() {

                int x=1,triangleNumber=1;

                while(triangleNumber<num){

                   x++;

                    triangleNumber = triangleNumber + x;

                }
                if(triangleNumber==num)
                {
                    System.out.println(num+" is a triangle number");
                    return true;
                }
                else
                {
                     System.out.println(num+" is applicable for both triangle and square numbers");

                }
                return false;

            }
        }


        Number mynum = new Number();
        mynum.num=2;
        System.out.println(mynum.isSquare());
    }