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Java Object toString()
What is a Object in Java?
In Java, an object is an instance of a class. A class defines a blueprint for an object, which includes the data (fields or properties) and behavior (methods or functions) of the object. An object is a specific instance of a class, with its own unique set of data and behavior.
- An object in Java is created using the new keyword, followed by the class name and constructor.
To know more about Object toString in java read the complete article.
Object tostring() method.
The toString() method in Java is a method that is defined in the Object class, which is the parent class of all classes in Java. It returns a string representation of an object. By default, the toString() method returns the name of the class, followed by the object’s memory address in hexadecimal format.
- The toString() method is often used for debugging and logging purposes, as well as for displaying the state of an object to the user.
Returns
Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object.
Note:
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.
Syntax:
public String toString()
Parameters:
The toString() method does not take any parameters.
Let’s look at a object-related Java program where the Java object tostring Method is used to perform an operation on the given string.
Example: Java Object tostring() Method
Run
class Book {
private String title;
private String author;
private int pages;
public Book(String title, String author, int pages) {
this.title = title;
this.author = author;
this.pages = pages;
}
@Override
public String toString() {
return title + " by " + author + ", " + pages + " pages";
}
}
public class Main {
public static void main(String[] args) {
Book book1 = new Book("Harry Potter", "J.K. Rowling", 320);
Book book2 = new Book("The Lord of the Rings", "J.R.R. Tolkien", 456);
System.out.println(book1.toString());
System.out.println(book2.toString());
}
}
Output
Harry Potter by J.K. Rowling, 320 pages The Lord of the Rings by J.R.R. Tolkien, 456 pages
Explanation:
In this example, the Book class has three fields, title, author, and pages, and a constructor that initializes these fields. The toString() method is overridden to return a string representation of the Book object that includes the title, author, and pages of the book.
Example 2 : Java String substring() Method
class Car {
private String make;
private String model;
private int year;
public Car(String make, String model, int year) {
this.make = make;
this.model = model;
this.year = year;
}
@Override
public String toString() {
return "Car: " + make + " " + model + " (" + year + ")";
}
}
public class Main {
public static void main(String[] args) {
Car car1 = new Car("Honda", "Civic", 2020);
Car car2 = new Car("Toyota", "Corolla", 2022);
System.out.println(car1.toString());
System.out.println(car2.toString());
}
}
Output
Car: Honda Civic (2020) Car: Toyota Corolla (2022)
Explanation:
In this example, the Car class has three fields, make, model, and year, and a constructor that initializes these fields. The toString() method is overridden to return a string representation of the Car object that includes the make, model, and year of the car.
The main class creates two instances of the Car class, car1 and car2, each with its own unique make, model, and year. The toString() method is called on each object, which returns a string representation of the object that includes the make, model, and year.
Example 3: how to use the object tostring property:
Run
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "Name: " + name + ", Age: " + age;
}
}
public class Main {
public static void main(String[] args) {
Person person1 = new Person("John", 30);
Person person2 = new Person("Jane", 25);
System.out.println(person1.toString());
System.out.println(person2.toString());
}
}
Output
Name: John, Age: 30 Name: Jane, Age: 25
Explanation:
In this example, the Person class has two fields, name and age, and a constructor that initializes these fields. The hashCode() method is overridden to return a hash code that is based on the name and age of the person. The calculation of the hash code is done using the name.hashCode() and age fields.
The main class creates two instances of the Person class, person1 and person2, each with its own unique name and age. The hashCode() method is called on each object, which returns a unique hash code for each object based on the name and age.
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