Java Inheritance error: Implicit Super Constructor is undefined

[phpnoob]

I am a novice to Java and just learning OOP concepts. Please review my code. I am getting the following error.- Implicit Super Constructor is undefined.\[code\]class BoxSuper{ int height; int length; int width; BoxSuper(BoxSuper obj) { height=obj.height; length=obj.length; width=obj.width; } BoxSuper(int a,int b,int c) { height=a; length=b; width=c; } BoxSuper(int val) { height=length=width=val; } int volume() { return height*length*width; }}class BoxSub extends BoxSuper{ int weight; BoxSub(int a,int b,int c,int d) { height=a; length=b; width=c; weight=d; }}\[/code\]