super()

package test;

public class Super {

protected int a;

protected Super(int a) { this.a = a; }

}

----------------

package test;

public class Sub extends Super{

public Sub(int a) { super(a); }

public Sub() { this.a = 5; }//implicitly add super(); but the Super class only has Super(int a)

}

ERROR: Implicit super constructor Super() is undefined. Must explicitly invoke another constructor