what does super mean in java

The super keyword in Java has three main uses: 1. Calling the parent class constructor; 2. Calling the parent class method; 3. Accessing the parent class fields.

Super meaning in Java

Super is a keyword in Java that is used in subclasses Access the methods and fields of the parent class. It has the following main uses:

1. Access the parent class constructor

When a subclass needs to call the parent class's constructor, you can use super() statement. This is usually done in the subclass's constructor. For example:

<code class="java">class Parent {
    int x;
    Parent(int x) {
        this.x = x;
    }
}

class Child extends Parent {
    int y;
    Child(int x, int y) {
        super(x); // 调用父类的构造函数
        this.y = y;
    }
}</code>

2. Calling parent class methods

Subclasses can call parent class methods through the super keyword. This is useful when a subclass needs to reimplement a parent class method. For example:

<code class="java">class Parent {
    void print() {
        System.out.println("父类方法");
    }
}

class Child extends Parent {
    @Override
    void print() {
        super.print(); // 调用父类的方法
        System.out.println("子类方法");
    }
}</code>

3. Accessing parent class fields

Subclasses can also access parent class fields through the super keyword. This is typically used to get the default value of a parent class or to redefine a field of a parent class. For example:

<code class="java">class Parent {
    int x;
}

class Child extends Parent {
    int y;
    Child(int x, int y) {
        super.x = x; // 访问父类的字段
        this.y = y;
    }
}</code>

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