toString method

[abalfazl hossein]

class Box {
double width;
double height;
double depth;
Box(double w, double h, double d) {
width = w;
height = h;
depth = d;
}
public String toString() {
return "Dimensions are " + width + " by " +
depth + " by " + height + ".";
}
}
class toStringDemo {
public static void main(String args[]) {
Box b = new Box(10, 12, 14);
String s = "Box b: " + b; // concatenate Box object
System.out.println(b); // convert Box to string
System.out.println(s);
}
} 

If all this mehtod do is return a string, Then I can define any method can do this! What is the real mission of this method?

[Wouter Oet]

Because every Object has the toString() method you can iterate through a Collection of objects and print the content. Also it is often used for debugging and logging purposes.

[Jesper de Jong]

abalfazl hossein wrote:If all this mehtod do is return a string, Then I can define any method can do this! What is the real mission of this method?

I don't understand your reasoning. It's as if you think that the purpose of the toString() method is so simple that it's not worthy of existence. As if every method you write has to do something important and complicated, something that you really have to think hard about, otherwise it's not worth it

Ofcourse you can write any other method that returns a string representation of the object. But it will not work in the same way as the toString() method, which will be called automatically when you do something like this:

Box box = ...;
System.out.println(box);  // Note, box.toString() will be called here, even if you don't do it explicitly