Must explicitly invoke another constructor

Question

Why is Eclipse keeps giving me error on the constructor:

 public DenseBoard(Tile t[][]){
      Board myBoard = new DenseBoard(t.length, t[0].length);
  }
         


        

Answer 1

I think what you want to do is this

public DenseBoard(Tile t[][]){
      this(t.length, t[0].length);
 }

Answer 2

Just to point out

public DenseBoard(Tile t[][]) {
    Board myBoard = new DenseBoard(t.length, t[0].length);
}

myBoard is local variable, you will not be able to refer it when you create a new object using new DenseBoard(Tile t[][]).

---

You can do it in 2 ways.

public DenseBoard(Tile t[][]) {
    super(t.length, t[0].length); // calling super class constructor
}

// or
// I would prefer this
public DenseBoard(Tile t[][]) {
    this(t.length, t[0].length); // calling DenseBoard(int rows, int cols) constuctor, which is internally passing the value to super class.
}

Answer 3

You can just do this to send the values up to parent class.

public DenseBoard(Tile t[][]){
      super(t.length, t[0].length);
 }

Answer 4

I think you DenseBoard class should implement all the Board class's abstract method. such like this:

package Game2048;
public class DenseBoard extends Board {

  public DenseBoard(int rows, int cols){
      super(rows, cols);
  }

  public DenseBoard(Tile t[][]){
      Board myBoard = new DenseBoard(t.length, t[0].length);
  }

  public Board copy(){

  }

  public int getRows(){

  }

  public int getCols(){

  }

  public int getTileCount(){

  }

  public int getFreeSpaceCount(){

  }

  public Tile tileAt(int i, int j){

  }

  public boolean lastShiftMovedTiles(){

  }

  public boolean mergePossible(){

  }

  public void addTileAtFreeSpace(int freeI, Tile tile){

  }

  public int shiftLeft(){

  }

  public int shiftRight(){

  }

  public int shiftUp(){

  }

  public int shiftDown(){

  }
}

Answer 5

Your constructor needs to call the constructor of the superclass. If the superclass had defined a no-argument constructor, you would not be seeing this error. To expand on the other answers with some code, what you need is

 public DenseBoard(Tile t[][]){
      //You need a way to figure meaningful values to the superconstructor here
      super(intVar1, intVar2);
      Board myBoard = new DenseBoard(t.length, t[0].length); //I think 
     //this now becomes unnecessary?
  }

Or alternatively modify your Board class to include

public Board()
{
...
}

Answer 6

In your class Board you only have one constructor which requires 2 int arguments.

And since DenseBoard extends Board, each of the constructor in DenseBoard should call some constructor in Board.

If Board had a no-arg constructor, the compiler would automatically call it for you. But since you don't have one, you should call another constructor explicitly from your public DenseBoard(Tile t[][]).