Java Community | Help. Code. Learn.•11mo ago

Week 57 — What is special about the `toString` method?

Question of the Week #57

What is special about the toString method?

7 Replies

All classes in Java have a toString() method which is supposed to return a String representation of the receiver object. By default, the toString method returns a String containing the (canonical) class name followed by @ and a hex representation of the result of the hashCode() method. Classes with a String representation are supposed to override the toString method which can be done like this:

public class SomeClass{
  private int someInt;
  private double someDouble;
  public SomeClass(int someInt, double someDouble){
    this.someInt = someInt;
    this.someDouble = someDouble;
  }

  @Override
  public String toString(){
    return "object of SomeClass with someInt=" + someInt + " and someDouble=" + someDouble;
  }
}

public class SomeClass{
  private int someInt;
  private double someDouble;
  public SomeClass(int someInt, double someDouble){
    this.someInt = someInt;
    this.someDouble = someDouble;
  }

  @Override
  public String toString(){
    return "object of SomeClass with someInt=" + someInt + " and someDouble=" + someDouble;
  }
}

Since that method is available on every object, it is commonly used by other code when Objects are displayed in some way. For example, PrintStream#println(Object) and string concatenation is using the toString() method for converting the object to a String:

SomeClass someObject = new SomeClass(42, 13.37);
System.out.println(someObject);//object of SomeClass with someInt=42 and someDouble=13.37

String stringRepresentation = "String representation: "+someObject;
System.out.println(stringRepresentation);//String representation: object of SomeClass with someInt=42 and someDouble=13.37

SomeClass someObject = new SomeClass(42, 13.37);
System.out.println(someObject);//object of SomeClass with someInt=42 and someDouble=13.37

String stringRepresentation = "String representation: "+someObject;
System.out.println(stringRepresentation);//String representation: object of SomeClass with someInt=42 and someDouble=13.37

📖 Sample answer from dan1st

Eric McIntyre•11mo ago

The toString() method in many programming languages is a special method that returns a string representation of an object. t is a built-in method. This means that it is automatically available to all objects in the language, without having to be explicitly defined. It is often overridden. This means that programmers can customize the behavior of the toString() method for their own classes. t is called implicit. This means that the compiler or interpreter automatically calls the toString() method when an object is converted to a string. This are the most special specifications of the toString() method

Submission from ibraa6305

Eric McIntyre•11mo ago

toString method can be overwritten allowing custom implementation of converting the object to String.

Eric McIntyre•11mo ago

Here is an example:

public class Person {
    private int age;

    public Person(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{Age=" + age + "}";
    }
}

public class Person {
    private int age;

    public Person(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{Age=" + age + "}";
    }
}

Submission from rooty

Eric McIntyre•11mo ago

toString method in Java is like a way for objects to describe themselves as strings. It's useful when you want to print or display information about an object in a human-readable format.

Submission from ig.imanish

Eric McIntyre•11mo ago

We can represent any object as an String and also return it

Submission from danix_225

Eric McIntyre•11mo ago

it belongs to the object class and its purpose is to create a string that best represents itself

Submission from abc8671

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Week 57 — What is special about the `toString` method?