What is it about?

There are no parent constructors that match the 'super()' that you are calling. Example:

class Ex1 {
   public Ex1(int temp) {

   }
}

class Ex2 extends Ex1 {
   public Ex2() {
      //super("5");  !~ERROR, no super constructor that takes a String
      //super();  !~ERROR, no super constructor with no arguments
      super(5); // this is good because it matches a parent constructor
   }
}

↑ Briefly two classes where the second class extends the first one. They both have constructors. In the child class you MUST call a valid constructor (literally any accessible constructor) from the parent class on the first line of code inside the child's constructor. The only time you don't need to use super in a constructor is if: 1) The parent class has a constructor with no parameter:

class Ex1 {
    public Ex1() {

    }
}

class Ex2 extends Ex1 {
    public Ex2() {
        // doesn't need super because parent has a constructor with no parameters
    }
}

2) The constructor calls another constructor with 'this' that calls a valid parents constructor:

class Ex1 {
   public Ex1(int temp) {

   }
}

class Ex2 extends Ex1 {
   public Ex2() {
      this(5); // calls another constructor that calls a parent's constructor
   }

    public Ex2(int temp) {
        super(5);
    }
}

Last little rule. Anytime you use 'super' or 'this' to call a constructor it MUST be the very first line of code in the constructor. Any lines of code prior to the super or this constructor call will produce an error:

constructor {
   int x = 5;
   super(x); // !~ this line of code will give you an error
}

constructor {
   int x = 5;
   this(x); // !~ this line of code will give you an error
}