Super Keyword

The super keyword in Java is used to refer immediate parent class object’s data member, methods, and constructors.

Whenever an instance of a subclass is created, an instance of parent class is also created implicitly. This can be referred by super reference variable.

Super example that refers parent class’ instance variable

package com.javatrainingschool;

public class Beverage {

	protected String state = "Liquid";
	
}

package com.javatrainingschool;

public class Tea extends Beverage {
	
	String state = "Brown Liquid";
	
	public void showBeverageState() {
		System.out.println("State of tea - " + state);
                //using super, we are accessing state variable of parent class Beverage
		System.out.println("State of beverage - " + super.state);
	}
	
	public static void main(String[] args) {
		
		Tea tea = new Tea();
		tea.showBeverageState();
	}
}

Output :

State of tea - Brown Liquid
State of beverage - Liquid

Super keyword example for accessing super class method

Super keyword can also be used to access super class’ method.

package com.javatrainingschool;

public class Beverage {

	protected String state = "Liquid";

        public void showBeverageState() {
            System.out.println("State of beverage - " + this.state);
        }
}

package com.javatrainingschool;

public class Tea extends Beverage {
	
	String state = "Brown Liquid";
	
	public void showBeverageState() {
		System.out.println("State of tea - " + state);
        }
        
        public void showState() {
                showBeverageState();
                //here super is used to refer to super class method
                super.showBeverageState();
        }
	
	public static void main(String[] args) {
		Tea tea = new Tea();
		tea.showState();
	}
}

Output :
State of tea - Brown Liquid
State of beverage - Liquid

Super keyword example to access super class constructor

package com.javatrainingschool;

public class Beverage {

        public Beverage() {
            System.out.println("From inside Beverage class constructor");
        }
}

package com.javatrainingschool;

public class Tea extends Beverage {
	
        public Tea() {
            super();   //this statement will call Beverage class' constructor
            System.out.println("From inside Tea class constructor");
        }
	
	public static void main(String[] args) {
		Tea tea = new Tea();
	}
}

Output :
From inside Beverage class constructor
From inside Tea class constructor