Javafx create rectangles in a loop

Question

I am learning Javafx and am having trouble getting my for loop to create a new rectangle on each iteration. When I run the program it creates one rectangle at the top left position and that is it. My goal is to create a grid of rectangles based on the amount of columns, rows, pixels wide, and pixels tall specified. Everything is tested to work besides the creation of rectangles.

for(int i = 0; i < columns; ++i)
    {//Iterate through columns
        for(int j = 0; j < rows; ++j)
        {//Iterate through rows
            Color choice = chooseColor(rectColors);
            //Method that chooses a color

            rect = new Rectangle(horizontal*j, vertical*i, horizontal, vertical);
            //Create a new rectangle(PosY,PosX,width,height)

            rect.setStroke(choice);
            //Give rectangles an outline so I can see rectangles

            root.getChildren().add(rect);
            //Add Rectangle to board

        }
    }

I am trying to figure out why the rectangles aren't being created. Any help would be greatly appreciated.

score 0 · Accepted Answer · answered Feb 10 '16 at 04:52

I used the same program which you had. Try with this and check where you made the mistake. Also check the values you initialized.

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class RectangleDemo extends Application{

    @Override
    public void start(Stage stage) {
        AnchorPane root = new AnchorPane();
        Scene scene = new Scene(root);
        stage.setScene(scene);

        int columns = 20, rows = 10 , horizontal = 20, vertical = 20;
        Rectangle rect = null;
        for(int i = 0; i < columns; ++i)
        {//Iterate through columns
            for(int j = 0; j < rows; ++j)
            {//Iterate through rows
//              Color choice = chooseColor(rectColors);
                //Method that chooses a color

                rect = new Rectangle(horizontal*j, vertical*i, horizontal, vertical);
                //Create a new rectangle(PosY,PosX,width,height)

                rect.setStroke(Color.RED);
                //Give rectangles an outline so I can see rectangles

                root.getChildren().add(rect);
                //Add Rectangle to board

            }
        }
        scene.setRoot(root);
        stage.show();

    }

    public static void main(String[] args) {
        launch(args);
    }
}

I hope it will help you...

This works but I forgot to mention I am using GridPane not AnchorPane. Other than that both of our code looks near identical. I want to use GridPane and it for whatever reason still does not work. — Solstice, Feb 10 '16 at 05:09
If you are using grid pane you have to mention the row index and column index. root.add(rect,j,i); use this instead of root.getChildren().add(rect); — Venkat Prasanna, Feb 10 '16 at 05:13
The code you told me to use did not compile but by using GridPane.setConstraints() I got it to work. Thank you so much! — Solstice, Feb 10 '16 at 05:22
The code i have said also will work buddy... you need to remove root.getchildren.add(rect); from you code and in the same place add root.add(rect,j,i); It will work for sure. and you are welcome :) — Venkat Prasanna, Feb 10 '16 at 05:27

Javafx create rectangles in a loop

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