Can Java Constructors Call Each Other?

Calling Constructors Within Classes in Java

It's common practice to create multiple constructors in a Java class to handle different object initialization scenarios. A unique question arises: can one constructor invoke another within the same class? Understanding this concept enhances your ability to create customizable constructors and maintain code organization.

To call one constructor from another, it's necessary to use the keyword this. For example:

public class Test {
    private int age;

    public Test() {
        this(18);
    }

    public Test(int age) {
        this.age = age;
    }
}

In this case, the first constructor with no arguments invokes the second constructor with an argument of 18. This allows you to initialize the age field with a default value when the caller doesn't provide an explicit age value.

However, note that chaining constructors is not limited to invoking constructors from the same class. It's also possible to invoke superclass constructors using the super keyword.

public class Child extends Parent {
    public Child() {
        super(10);
    }
}

Here, the Child class constructor calls the Parent class constructor with an argument of 10. This is particularly useful for initializing inherited fields.

As the documentation emphasizes, only one constructor call is allowed in your constructor body, and it must be the first statement. This ensures that the object is properly initialized before executing any other code. Additionally, the same principles apply when invoking superclass constructors.

By understanding the ability to call one constructor from another, you can create reusable and flexible constructors, enhance code readability, and maintain consistency in your object initialization processes.

The above is the detailed content of Can Java Constructors Call Each Other?. For more information, please follow other related articles on the PHP Chinese website!