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:
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; } }
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:
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"); } }
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:
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; } }
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