Java Object toString() Method

The Object.toString() method in Java is used to return a string representation of an object.

Table of Contents

1. Introduction
2. toString() Method Syntax
3. Examples
   • Default toString()
   • Overriding toString()
   • Using toString() in Collections
4. Real-World Use Case
5. Conclusion

Introduction

The Object.toString() method is a member of the Object class in Java. It returns a string representation of the object. By default, the toString() method returns a string that consists of the class name followed by the "@" character and the object's hash code in hexadecimal. However, this method can be overridden to provide a more meaningful string representation of an object.

toString()() Method Syntax

The syntax for the toString() method is as follows:

public String toString()

The method returns a string representation of the object.

Examples

Default toString()

The default implementation of the toString() method in the Object class returns the class name followed by the "@" character and the object's hash code in hexadecimal.

Example

public class DefaultToStringExample {
    public static void main(String[] args) {
        Object obj = new Object();
        System.out.println(obj.toString());
    }
}

Output:

java.lang.Object@15db9742

Overriding toString()

To provide a meaningful string representation of an object, you can override the toString() method in your class.

Example

class Person {
    String name;
    int age;

    Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

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

public class CustomToStringExample {
    public static void main(String[] args) {
        Person person = new Person("Ramesh", 30);
        System.out.println(person.toString());
    }
}

Output:

Person{name='Ramesh', age=30}

Using toString() in Collections

When objects are stored in collections, the toString() method is used to provide a string representation of the objects in the collection.

Example

import java.util.ArrayList;
import java.util.List;

public class CollectionToStringExample {
    public static void main(String[] args) {
        List<Person> people = new ArrayList<>();
        people.add(new Person("Ramesh", 30));
        people.add(new Person("Suresh", 25));

        System.out.println(people.toString());
    }
}

Output:

[Person{name='Ramesh', age=30}, Person{name='Suresh', age=25}]

Real-World Use Case

Logging and Debugging

In real-world scenarios, the toString() method is often overridden to provide a useful string representation of an object for logging and debugging purposes.

Example

class Product {
    String name;
    double price;

    Product(String name, double price) {
        this.name = name;
        this.price = price;
    }

    @Override
    public String toString() {
        return "Product{name='" + name + "', price=" + price + "}";
    }
}

public class LoggingExample {
    public static void main(String[] args) {
        Product product = new Product("Laptop", 800.0);
        System.out.println("Logging product: " + product);
    }
}

Output:

Logging product: Product{name='Laptop', price=800.0}

Conclusion

The Object.toString() method in Java is a fundamental method for providing a string representation of an object. By understanding how to use and override this method, you can ensure that your objects have meaningful and useful string representations. Whether you are using the default implementation, overriding the method for custom representations, or using it in real-world scenarios like logging and debugging, the toString() method provides a reliable way to convert objects to strings in Java applications.