constructor chaining

Bar.java

private int constant;
 
	private Bar(){
		//System.out.println("tewsts");
		//this(5);
		System.out.println("default constructor is called");
	}
	
	private static boolean instanceAvailable;
	private static Bar bar;

	public static Bar getInstance() {
		if (!instanceAvailable) {
			bar = new Bar();
			instanceAvailable = true;
		}
		return bar;
	}
	
	public void test(){
		
	}
	
	public static void main(String[] args){
		//Bar b = new Bar(5);
		//b.test();
		// output :
		//abstract Foo class constructor is invoked
		//Bar constructor is invoked

	}

Foo.java

package constructors.constructorChaining;

public abstract class Foo {
	public Foo(){
		System.out.println("abstract Foo class constructor is invoked");
	}
	public abstract void test();
}