Java label setText and setBounds clashing?

Question

I would like the color of the JLabel change to be random, while moving to an arbitrary position and changing its text.

but setText and setBounds seem to have collided, and I don't know why. if you comment out setText, then setBounds will work, but they will not work together.

import java.awt.*; import java.util.*; import javax.swing.*; public class test2 extends JFrame { private static JLabel label = new JLabel("0"); private static Random gen = new Random(); public test2() { JPanel panel = new JPanel(); panel.add(label); this.add(panel); } public static void move() { for (int i = 0; i < 10; i++) { int n = gen.nextInt(254)+1; int nn = gen.nextInt(254)+1; int nnn = gen.nextInt(254)+1; label.setText(""+i); //the setBounds command will not work with the setText command. why? label.setBounds(n*2, nn*2, 20, 20); label.setForeground(new Color(n, nn, nnn)); try { Thread.sleep(200); } catch (Exception e) {} } } public static void main(String[] args) { test2 frame = new test2(); frame.setVisible(true); frame.setSize(600, 600); frame.setResizable(true); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); move(); } } 

Answer 1

setBounds should not work with a non-empty layout, and your problem is because changing the text in JLabel encourages the re-layout of the JPanel, and since JPanels use FlowLayout by default, the JLabel stays at the top in the middle. Therefore, if you really need this functionality, consider setting the JPanel layout to null, or use JLayeredPane.

  public test2() { JPanel panel = new JPanel(null); panel.add(label); this.add(panel); } 

Also, you should not call Thread.sleep (...) on the EDT, the Swing thread. Instead, consider using a Swing timer.

Since I disagree with another example, I will post an example of what I recommended instead, using the Swing timer:

 import java.awt.*; import java.awt.event.*; import java.util.Random; import javax.swing.*; @SuppressWarnings("serial") public class Test3 extends JPanel { private static final int SIDE = 600; public static final int MAX_COUNTER = 20; private static final int TIMER_DELAY = 400; private static final int MAX_RAND = 220; private int counter = 0; private JLabel label = new JLabel(String.valueOf(counter)); private Random gen = new Random(); private int[] randNumb = new int[3]; public Test3() { setPreferredSize(new Dimension(SIDE, SIDE)); setLayout(null); add(label); new Timer(TIMER_DELAY, new TimerListener()).start(); } private void myMove() { for (int i = 0; i < randNumb.length; i++) { randNumb[i] = gen.nextInt(MAX_RAND); } label.setText(String.valueOf(counter)); label.setSize(label.getPreferredSize()); label.setLocation((SIDE * randNumb[0])/MAX_RAND, (SIDE*randNumb[1])/MAX_RAND); label.setForeground(new Color(randNumb[0], randNumb[1], randNumb[2])); repaint(); } private class TimerListener implements ActionListener { public void actionPerformed(ActionEvent e) { if (counter < MAX_COUNTER) { myMove(); counter++; } else { ((Timer)e.getSource()).stop(); } } } private static void createAndShowUI() { JFrame frame = new JFrame("Test3"); frame.getContentPane().add(new Test3()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } public static void main(String[] args) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { createAndShowUI(); } }); } } 

Answer 2

I don't know why this is happening, but the ugly job here is:

 package com.me; import java.awt.Color; import java.util.Random; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; public class test2 extends JFrame { private static int i; private static JLabel label = new JLabel("0"){ @Override public String getText(){ return i+""; } }; private static Random gen = new Random(); public test2() { JPanel panel = new JPanel(); panel.add(label); this.add(panel); } public static void move() { for (i = 0; i < 10; i++) { int n = gen.nextInt(254)+1; int nn = gen.nextInt(254)+1; int nnn = gen.nextInt(254)+1; //the setBounds command will not work with the setText command. why? label.setBounds(n*2, nn*2, 20, 20); label.setForeground(new Color(n, nn, nnn)); try { Thread.sleep(200); } catch (Exception e) {} } } public static void main(String[] args) { test2 frame = new test2(); frame.setVisible(true); frame.setSize(600, 600); frame.setResizable(true); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); move(); } 

}