How to use the toString() in Java

class HelloWorld {
    public static void main( String args[] ) {
        //Creating an integer of value 10
        Integer number=10;
        // Calling the toString() method as a function of the Integer variable
        System.out.println( number.toString() );
    }
}

class HelloWorld {
    public static void main( String args[] ) {
        
        // The method is called on datatype Double
        // It is passed the double value as an argument
        System.out.println(Double.toString(11.0)); 
        // Implementing this on other datatypes
        //Integer
        System.out.println(Integer.toString(12)); 
        // Long
        System.out.println(Long.toString(123213123));
        // Boolean
        System.out.println(Boolean.toString(false));
    }
}

class Pet{
  String name;
  Integer age; 
  Pet(String n, Integer a){
    this.name=n;
    this.age=a;
  }
//Over-riding the toString() function as a class function
  public String toString(){
    return "The name of the pet is " + this.name + ". The age of the pet is " + this.age;
  }
}
class HelloWorld {
    public static void main( String args[] ) {
      Pet p = new Pet("Jane",10);
      //Calling the class version of toString()
        System.out.println(p.toString());
      //Calling the original toString()
      System.out.println(Integer.toString(12));
    }
}