Update GridPane with Slider in JavaFx - javafx

Question

I'm new at this, I´m creating a field that solves N x N Matrixes, and I want the spinner to add more TextFields every time I change its value, so the user can select the size of the matrix and then solve it...However I don't know how to do this.
I've tried to attach a listener JavaFX spinner but it didn't work, and it has created some errors in the code.
The code in question...
public static void main(String[] args) {
// TODO Auto-generated method stub
launch(args);
}
public void start(Stage primaryStage) throws Exception{
Double[][] A = new Double[6][6];
Label tamanoML = new Label("Tamaño Matriz:");
Spinner tamanoMS =new Spinner(1,5,0,1);
int tamano=(int) tamanoMS.getValue();
int r;
Label[] campoL = new Label[6];
TextField campo [][] = new TextField[6][6];
Button resolverB = new Button("Resolver matrix");
resolverB.setOnAction((ActionEvent t) -> {
int n=(int) tamanoMS.getValue();
int cont=0;
for(int i=0; i<n; i++) {
for(int j=0; j<n+1; j++) {
A[i][j]=Double.parseDouble(campo[i][j].getText());
}
}
for (int a = 0; a < n; a++) {
Double temp = 0.0;
temp = A[cont][cont];
for (int y = 0; y < (n + 1); y++) {
A[cont][y] = A[cont][y] / temp;
}
for (int x = 0; x < n; x++) {
if (x!=cont) {
Double c = A[x][cont];
for (int z = 0; z < (n + 1); z++) {
A[x][z] = ((-1 * c) * A[cont][z]) + A[x][z];
}
}
}
cont++;
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n+1; j++) {
campo[i][j].setText(""+A[i][j]);
}
}
});
Button limpiarb = new Button("Limpiar");
limpiarb.setOnAction((ActionEvent t) -> {
for(int i=0; i<tamano+1; i++) {
for(int j=0; j<tamano+1; j++) {
campo[i][j].setText("0");
}
}
});
GridPane mainPane = new GridPane();
mainPane.setMinSize(650,350);
mainPane.setPadding(new Insets(10,10,10,10));
mainPane.setVgap(5);
mainPane.setHgap(5);
mainPane.setAlignment(Pos.CENTER);
mainPane.add(tamanoML, 0, 0);
mainPane.add(tamanoMS, 1, 0);
mainPane.add(resolverB,0,1);
mainPane.add(limpiarb,1,1);
for(int i=0; i<tamano+1; i++) {
r=i+1;
if(r<tamano+1) {
r=i+1;
campoL[i]=new Label("X"+r);
mainPane.add(campoL[i],i,2);
}else {
campoL[i]=new Label("R");
mainPane.add(campoL[i],i,2);
}
}
for(int i=0; i<tamano; i++) {
for(int j=0; j<tamano+1; j++) {
campo[i][j] = new TextField("0");
mainPane.add(campo[i][j],j,i+3);
}
}
tamanoMS.valueProperty().addListener((newValue) -> {
int s;
for(int i=0; i<tamano+1; i++) {
s=i+1;
if(s<tamano+1) {
s=i+1;
campoL[i]=new Label("X"+s);
mainPane.add(campoL[i],i,2);
}else {
campoL[i]=new Label("R");
mainPane.add(campoL[i],i,2);
}
}
for(int i=0; i<tamano; i++) {
for(int j=0; j<tamano+1; j++) {
campo[i][j] = new TextField("0");
mainPane.add(campo[i][j],j,i+3);
}
}
s=0;
});
Scene scene = new Scene(mainPane);
primaryStage.setScene(scene);
primaryStage.setTitle("Ventas del Dia");
primaryStage.show();
}

Answer 1

Ok so the first thing you want to do is rewrite your listener like this
tamanoMS.valueProperty().addListener((obs, oldValue, newValue) -> {
System.out.println("heard");
int s;
for(int i=0; i<newValue+1; i++) {
s=i+1;
if(s<newValue+1) {
s=i+1;
campoL[i]=new Label("X"+s);
mainPane.add(campoL[i],i,2);
}else {
campoL[i]=new Label("R");
mainPane.add(campoL[i],i,2);
}
}
for(int i=0; i<newValue; i++) {
for(int j=0; j<newValue+1; j++) {
campo[i][j] = new TextField("0");
mainPane.add(campo[i][j],j,i+3);
}
}
s=0;
});
I'm gonna be honest I don't quite understand why you need oldValue and obs but you do. However, the reason your matrix wasn't expanding was because you weren't updating tamano to the most recent number.
You also need to change your spinner to this so that is know the value that is coming out is an integer.
Spinner<Integer> tamanoMS =new Spinner<Integer>(1,5,0,1);