toString() method

[jhon max]

   public class Operations {

    private int number;

    public Operations(int num) {

        setTheNumber(num);
    }

    private void setTheNumber(int number) {

        this.number = number;
    }

    public int getNumber() {

        return number;
    }
    
    public Operations add(Operations op) {
        
        int num1,
            num2;

        num1 = this.getNumber(); // refers to the receiving objects data members
        num2 = op.getNumber();   // refers to the argument object

        Operations sum = new Operations(num1 + num2);

        return sum;
    }

    public Operations subtract(Operations op) {

        int num1,
            num2;

        num1 = this.getNumber();
        num2 = op.getNumber();

        Operations difference = new Operations(num1 - num2);

        return difference;
    }
    
    // when i add this method
    public String toString() {

        return getNumber() + "" ;
    }
    
    public Operations divide(Operations op) {

        int num1,
            num2;

        num1 = this.getNumber();
        num2 = op.getNumber();

        if (num1 == 0 || num2 == 0) {

            System.err.print("Cannot Divide By Zero");
            System.exit(1);
        }

        Operations quotient = new Operations(num1 / num2);

        return quotient;
    }

    public Operations multiply(Operations op) {

        int num1,
            num2;

        num1 = this.getNumber();
        num2 = op.getNumber();
        
        Operations product = new Operations(num1 * num2);

        return product;
    }

    // Main
    public static void main(String[] args) {

        Operations num1,
                   num2;

        Operations sum,
                   diff,
                   quot,
                   prod;

        num1 = new Operations(10);
        num2 = new Operations(5);

        sum = num1.add(num2);
        diff = num1.subtract(num2);
        quot = num1.divide(num2);
        prod = num1.multiply(num2);

        System.out.println(sum);
        System.out.println(diff);
        System.out.println(quot);
        System.out.println(prod);
    }
} 

when im not yet Overriding the toString() method the output is
this:

  xxTestxx.Operations@3e25a5
xxTestxx.Operations@19821f
xxTestxx.Operations@addbf1
xxTestxx.Operations@42e816  

but when i include the toString() method
the output became fine:

  15
5
2
50  

but i only added the toString() method... i didnt use this method in any of my predefined methods? how does it affects the correct output?

by the way, to be honest i've already posted this thread in other forums, but i need some more clarification of why this happened...
http://www.java-forums.org/new-java/24496-returning-object-method.html - cross posted

[Jack Ploeg]

if you don't override toString then the toString implementation of Object is used, since that's the only class your class extends. This returns a string that identifies the class of your object and somthing like an address.

[jhon max]

if you don't override toString then the toString implementation of Object is used, since that's the only class your class extends

so if i dont override the toString method properly, then my class will AUTOMATICALY extend as an object? and my Class
will use the Object class's toString() method to make a string representation of its object...?

---

in my case im reffering to the String class? not in the object class?


is that how the toString() of String class works and differs from the toString() method of Object class?

[Jack Ploeg]

EVERY class extends the Java base-class Object. Check here: Java Object So every class automatically inherits this Object class's implementation of toString. As you found out you can override this to do whatever you want it to, but if you don't then the default implementation is used.

[W. Joe Smith]

jhon max wrote:

if you don't override toString then the toString implementation of Object is used, since that's the only class your class extends

so if i dont override the toString method properly, then my class will AUTOMATICALY extend as an object? and my Class
will use the Object class's toString() method to make a string representation of its object...?

---

in my case im reffering to the String class? not in the object class?


is that how the toString() of String class works and differs from the toString() method of Object class?

Every class extends Object, no matter what. So if you call toString() on any class that doesn't override the method, it will walk up the hierarchy to find the most specific toString(). If there isn't one, it will use the Object class's toString() method.

[jhon max]

hmm this is a bit confusing and for me ryt now... anyway tnx for the answers!!!

[Bear Bibeault]

jhon max wrote:hmm this is a bit confusing and for me ryt now... anyway tnx for the answers!!!

Please use real words when posting to the forums. Abbreviations such as "ryt" in place of "right" and "tnx" for "thanks" only serve to make your posts more difficult to read and less likely to generate useful responses.

Please read this for more information.

thanks,
bear
JavaRanch sheriff

[jhon max]

oh sorry sir... wont happen again.. anywany thanks for letting me know about that,,