How to use the toString method in Java?

From the Object.toString docs:

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

getClass().getName() + '@' + Integer.toHexString(hashCode())

Example:

String[] mystr ={"a","b","c"};
System.out.println("mystr.toString: " + mystr.toString());

output:- mystr.toString: [Ljava.lang.String;@13aaa14a

Use of the String.toString:

Whenever you require to explore the constructor called value in the String form, you can simply use String.toString... for an example...

package pack1;

import java.util.*;

class Bank {

    String n;
    String add;
    int an;
    int bal;
    int dep;

    public Bank(String n, String add, int an, int bal) {

        this.add = add;
        this.bal = bal;
        this.an = an;
        this.n = n;

    }

    public String toString() {
        return "Name of the customer.:" + this.n + ",, "
                + "Address of the customer.:" + this.add + ",, " + "A/c no..:"
                + this.an + ",, " + "Balance in A/c..:" + this.bal;
    }
}

public class Demo2 {

    public static void main(String[] args) {

        List<Bank> l = new LinkedList<Bank>();

        Bank b1 = new Bank("naseem1", "Darbhanga,bihar", 123, 1000);
        Bank b2 = new Bank("naseem2", "patna,bihar", 124, 1500);
        Bank b3 = new Bank("naseem3", "madhubani,bihar", 125, 1600);
        Bank b4 = new Bank("naseem4", "samastipur,bihar", 126, 1700);
        Bank b5 = new Bank("naseem5", "muzafferpur,bihar", 127, 1800);
        l.add(b1);
        l.add(b2);
        l.add(b3);
        l.add(b4);
        l.add(b5);
        Iterator<Bank> i = l.iterator();
        while (i.hasNext()) {
            System.out.println(i.next());
        }
    }

}

... copy this program into your Eclipse, and run it... you will get the ideas about String.toString...

The toString() method returns a textual representation of an object. A basic implementation is already included in java.lang.Object and so because all objects inherit from java.lang.Object it is guaranteed that every object in Java has this method.

Overriding the method is always a good idea, especially when it comes to debugging, because debuggers often show objects by the result of the toString() method. So use a meaningful implementation but use it for technical purposes. The application logic should use getters:

public class Contact {
  private String firstName;
  private String lastName;
  public Contact (String firstName, String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }
  public String getFirstName() {return firstName;}
  public String getLastName() {return lastName;}

  public String getContact() {
    return firstName + " " + lastName;
  }

  @Override
  public String toString() {
    return "["+getContact()+"]";
  }
}

It may optionally have uses within the context of an application but far more often it is used for debugging purposes. For example, when you hit a breakpoint in an IDE, it's far easier to read a meaningful toString() of objects than it is to inspect their members.

There is no set requirement for what a toString() method should do. By convention, most often it will tell you the name of the class and the value of pertinent data members. More often than not, toString() methods are auto-generated in IDEs.

Relying on particular output from a toString() method or parsing it within a program is a bad idea. Whatever you do, don't go down that route.