String toString()

The `toString()` method is a method that belongs to the `Object` class in Java. It is used to return a string representation of an object.

When you call `toString()` on an object, the method will return a string that represents the object in a human-readable format. By default, the `toString()` method returns a string that contains the class name of the object, followed by an "@" symbol, and then the object's hash code in hexadecimal format.

For example, consider the following code:

Person person = new Person("John", "Doe", 30);
System.out.println(person.toString());

Assuming the `Person` class has not overridden the `toString()` method, the output of this code would be:

Person@3b6eb2ec

However, the `toString()` method can be overridden in a class to provide a more meaningful string representation of an object. For example:

public class Person {
    private String firstName;
    private String lastName;
    private int age;

    public Person(String firstName, String lastName, int age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }

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

Now, when you call `toString()` on a `Person` object, you will get a string that contains the person's first name, last name, and age, in a readable format:

Person{firstName='John', lastName='Doe', age=30}

Note: The `toString()` method is automatically called when you pass an object to the `System.out.println()` method, so you don't need to explicitly call `toString()` in most cases.