What does super refer to in java

Super in Java is used to access methods and member variables of the parent class. Its main uses include calling the parent class constructor, accessing parent class methods, and accessing parent class variables. Use super() in the subclass to call the parent class constructor, super.methodName() to access the parent class method, and super.variableName to access the parent class variable. Note: super can only be used in subclasses and must be the first line of the statement.

super in Java

super is a keyword in Java, used to access the methods of the parent class and member variables.

Uses

super has the following main uses:

• Call the parent class constructor: In the child Use super() in the constructor of a class to call the constructor of the parent class.
• Access the parent class method: Access the parent class method through super.methodName() in the subclass.
• Access parent class variables: Access the variables of the parent class through super.variableName in the subclass.

Example

The following example shows how to use super:

class Parent {
    public Parent() {
        System.out.println("Parent constructor");
    }
    public void print() {
        System.out.println("Parent method");
    }
}

class Child extends Parent {
    public Child() {
        super(); // 调用父类构造函数
        System.out.println("Child constructor");
    }
    @Override
    public void print() {
        super.print(); // 访问父类方法
        System.out.println("Child method");
    }
}

public class Main {
    public static void main(String[] args) {
        Child child = new Child();
        child.print(); // 输出：Parent constructor, Child constructor, Parent method, Child method
    }
}

Notes

• super can only be used in subclasses, not in parent classes or independent classes.
• super must be used as the first line of the statement and cannot be mixed with other codes.
• If the subclass does not explicitly call the parent class constructor, the compiler will automatically add an implicit call.

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