Issue
I had to create a matrix in javaFX. I created it without any problem with GridPane. The next thing is to create like "buttons" on the right side of the matrix, these buttons will move +1 element of the matrix to the right. Like this:
110 <-
101 <- //ie: I clicked this button
100 <-
The result:
110 <-
110 <-
100 <-
The way I handle this bit-shifting-moving was with circular linked list. I don't have any problem with that I think you can ommit that part. I use this method:
private void moveRowRight(int index){
//recives a index row and moves +1 the elements of that row in the matrix.
}
cells is the matrix
The problem is that, first the matrix can be modified by the user input i.e. 5x5 6x6 7x7, so the number of buttons will also change. I tried using a BorderPane(center: gridpane(matrix), right: VBox()) and this is the part of the code how I added some HBox inside the Vbox (right part of the border pane) and using the setOnMouseClicked.
private void loadButtonsRight(){
for(int i = 0; i < cells[0].length ; i++){
HBox newBox = new HBox();
newBox.getChildren().add(new Text("MOVE"));
newBox.prefHeight(50);
newBox.prefWidth(50);
newBox.setOnMouseClicked(e -> {
moveRowRight(i);
});
VBRightButtons.getChildren().add(newBox); //where I add the HBox to the VBox (right part of the Border Pane)
}
}
}
But then there's this problem.
Local variables referenced from lambda expression must be final or effectively final
It seems that I cannot implement lambda with a value that will change. Is there any way to help me to put "buttons" that depends of the matrix size and that uses the method I've created?
Solution
The message tells you all you need to know to fix the problem:
Local variables referenced from lambda expression must be final or effectively final
Assign your changing variable to a final constant and use the constant value in the lambda instead of the variable:
final int idx = i;
newBox.setOnMouseClicked(e ->
moveRowRight(idx);
);
If you wish to understand this more, see the baeldung tutorial
Answered By - jewelsea
Answer Checked By - Marilyn (JavaFixing Volunteer)
