How to call one constructor from another?

Question

Aryan Kumar · Answer

In Java, you can call one constructor from another using the this() keyword. The this() keyword refers to the current object.

To call one constructor from another, you need to use the this() keyword followed by the name of the constructor you want to call. The constructor you want to call must be defined in the same class as the constructor that is calling it.

Here is an example of how to call one constructor from another in Java:

Java

class Person {
    public Person() {
        // This is the default constructor.
    }

    public Person(String name) {
        // This constructor takes a name parameter.
        this(); // Call the default constructor first.
        this.name = name;
    }

    private String name;
}

In this example, the Person() constructor is the default constructor. The Person(String name) constructor takes a name parameter. The first line of the Person(String name) constructor calls the Person() constructor first. This is done to ensure that the fields of the Person class are initialized before the name property is set.

Here is another example:

Java

class Person {
    public Person(String name, int age) {
        // This constructor takes a name and age parameter.
        this(name); // Call the constructor that takes a name parameter first.
        this.age = age;
    }

    public Person(String name) {
        // This constructor takes a name parameter.
        this.name = name;
    }

    private String name;
    private int age;
}

In this example, the Person(String name, int age) constructor calls the Person(String name) constructor first. This is done to ensure that the name property is initialized before the age property is set.

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How to call one constructor from another?

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