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Memory leak when using setText

I noticed that I have a memory leak in my program.

I traced the problem to the line.

Clock.setText("" + h + ":" + df.format(m) + ":" + df.format(s));

I have googled this and this seems to be a common problem, but I did not find an answer.

Does anyone know a fix?

Here is the whole code:

 package CodeBits; import java.awt.Color; import java.awt.EventQueue; import java.awt.Font; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.Insets; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.text.DecimalFormat; import java.util.Calendar; import java.util.GregorianCalendar; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JTextField; public class Countdown { private JFrame Timer; private JTextField Clock; private JLabel label; private JLabel label_1; static Calendar calendar = new GregorianCalendar(); int minutes = 90; int count = minutes * 60; int h; int m; int s; javax.swing.Timer refreshTimer; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { Countdown window = new Countdown(); window.Timer.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the application. */ public Countdown() { initialize(); } /** * Initialize the contents of the frame. */ private void initialize() { Timer = new JFrame(); Timer.getContentPane().setBackground(new Color(173, 216, 230)); Timer.setBounds(0, 0, 135, 100); Timer.setTitle("Aero Software"); Timer.setIconImage(Toolkit.getDefaultToolkit().getImage("Files/Icon.jpg")); Timer.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); GridBagLayout gridBagLayout = new GridBagLayout(); gridBagLayout.columnWidths = new int[]{0, 0, 0, 0, 0, 0}; gridBagLayout.rowHeights = new int[]{0, 0, 0, 0, 0, 0, 0, 0}; gridBagLayout.columnWeights = new double[]{0.0, 0.0, 1.0, 1.0, 0.0, Double.MIN_VALUE}; gridBagLayout.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE}; Timer.getContentPane().setLayout(gridBagLayout); label = new JLabel(" "); GridBagConstraints gbc_label = new GridBagConstraints(); gbc_label.insets = new Insets(0, 0, 5, 5); gbc_label.gridx = 0; gbc_label.gridy = 1; Timer.getContentPane().add(label, gbc_label); JLabel lblNewLabel = new JLabel("Countdown Timer"); GridBagConstraints gbc_lblNewLabel = new GridBagConstraints(); gbc_lblNewLabel.gridwidth = 4; gbc_lblNewLabel.insets = new Insets(0, 0, 5, 0); gbc_lblNewLabel.gridx = 1; gbc_lblNewLabel.gridy = 1; Timer.getContentPane().add(lblNewLabel, gbc_lblNewLabel); Clock = new JTextField(); Clock.setFont(new Font("Arial", Font.BOLD, 22)); Clock.setHorizontalAlignment(JLabel.CENTER); GridBagConstraints gbc_Clock = new GridBagConstraints(); gbc_Clock.fill = GridBagConstraints.HORIZONTAL; gbc_Clock.gridwidth = 3; gbc_Clock.insets = new Insets(0, 0, 5, 5); gbc_Clock.gridx = 1; gbc_Clock.gridy = 2; Timer.getContentPane().add(Clock, gbc_Clock); Clock.setColumns(10); label_1 = new JLabel(" "); GridBagConstraints gbc_label_1 = new GridBagConstraints(); gbc_label_1.insets = new Insets(0, 0, 5, 0); gbc_label_1.gridx = 4; gbc_label_1.gridy = 2; Timer.getContentPane().add(label_1, gbc_label_1); // Create countdown timer ActionListener refreshListener = new ActionListener() { // Ensure time is fotmatted as 7:04 not 7:4 DecimalFormat df = new DecimalFormat("00"); Calendar countdown = calendar; { // Zero the time and add the number of minutes to countdown from countdown.set(Calendar.HOUR, 0); countdown.set(Calendar.MINUTE, 0); countdown.set(Calendar.SECOND, 0); countdown.set(Calendar.MINUTE, 0); countdown.add(Calendar.MINUTE, minutes); } // Start the timer public void actionPerformed(ActionEvent e) { h = countdown.get(Calendar.HOUR_OF_DAY); m = countdown.get(Calendar.MINUTE); s = countdown.get(Calendar.SECOND); calendar.add(Calendar.SECOND, -1); Clock.setText("" + h + ":" + df.format(m) + ":" + df.format(s)); count--; if (count == 0) { System.out.println("Time is up!"); refreshTimer.stop(); } } }; refreshTimer = new javax.swing.Timer(1000, refreshListener); refreshTimer.setInitialDelay(0); refreshTimer.start(); } }
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2 answers

Your program looks good to me. Notice how the periodic GC returns to its original level. In contrast, this is an example of a host resource leak. At best, you can use StringBuilder or MessageFormat in your setText() call.

enter image description here

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Here is the result of a slightly modified version of the code.

 14145904 13602336 13059104 12515968 12063384 15263600 14758304 14253408 13748576 13197160 12646360 12057192 11552120 15472056 14960064 14448336 13875144 13363416 12851488 12309120 11681480 15661104 15142224 14602560 14063128 13523464 12983832 12444168 11904536 11364648 15325136 14770848 14230296 13690032 ..

I do not see a memory leak here.

Modified code

 import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.text.DecimalFormat; import java.util.Calendar; import java.util.GregorianCalendar; import javax.swing.*; public class Countdown { private JFrame Timer; private JTextField Clock; private JLabel label; private JLabel label_1; static Calendar calendar = new GregorianCalendar(); int minutes = 90; int count = minutes * 60; int h; int m; int s; javax.swing.Timer refreshTimer; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { Countdown window = new Countdown(); window.Timer.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the application. */ public Countdown() { initialize(); } /** * Initialize the contents of the frame. */ private void initialize() { Timer = new JFrame(); Timer.getContentPane().setBackground(new Color(173, 216, 230)); Timer.setBounds(0, 0, 135, 100); Timer.setTitle("Aero Software"); Timer.setIconImage(Toolkit.getDefaultToolkit().getImage("Files/Icon.jpg")); Timer.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); GridBagLayout gridBagLayout = new GridBagLayout(); gridBagLayout.columnWidths = new int[]{0, 0, 0, 0, 0, 0}; gridBagLayout.rowHeights = new int[]{0, 0, 0, 0, 0, 0, 0, 0}; gridBagLayout.columnWeights = new double[]{0.0, 0.0, 1.0, 1.0, 0.0, Double.MIN_VALUE}; gridBagLayout.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE}; Timer.getContentPane().setLayout(gridBagLayout); label = new JLabel(" "); GridBagConstraints gbc_label = new GridBagConstraints(); gbc_label.insets = new Insets(0, 0, 5, 5); gbc_label.gridx = 0; gbc_label.gridy = 1; Timer.getContentPane().add(label, gbc_label); JLabel lblNewLabel = new JLabel("Countdown Timer"); GridBagConstraints gbc_lblNewLabel = new GridBagConstraints(); gbc_lblNewLabel.gridwidth = 4; gbc_lblNewLabel.insets = new Insets(0, 0, 5, 0); gbc_lblNewLabel.gridx = 1; gbc_lblNewLabel.gridy = 1; Timer.getContentPane().add(lblNewLabel, gbc_lblNewLabel); Clock = new JTextField(); Clock.setFont(new Font("Arial", Font.BOLD, 22)); Clock.setHorizontalAlignment(JLabel.CENTER); GridBagConstraints gbc_Clock = new GridBagConstraints(); gbc_Clock.fill = GridBagConstraints.HORIZONTAL; gbc_Clock.gridwidth = 3; gbc_Clock.insets = new Insets(0, 0, 5, 5); gbc_Clock.gridx = 1; gbc_Clock.gridy = 2; Timer.getContentPane().add(Clock, gbc_Clock); Clock.setColumns(10); label_1 = new JLabel(" "); GridBagConstraints gbc_label_1 = new GridBagConstraints(); gbc_label_1.insets = new Insets(0, 0, 5, 0); gbc_label_1.gridx = 4; gbc_label_1.gridy = 2; Timer.getContentPane().add(label_1, gbc_label_1); ActionListener memoryListener = new ActionListener() { public void actionPerformed(ActionEvent ae) { System.out.println(Runtime.getRuntime().freeMemory()); } }; Timer memTimer = new Timer(1000,memoryListener); memTimer.start(); // Create countdown timer ActionListener refreshListener = new ActionListener() { // Ensure time is fotmatted as 7:04 not 7:4 DecimalFormat df = new DecimalFormat("00"); Calendar countdown = calendar; { // Zero the time and add the number of minutes to countdown from countdown.set(Calendar.HOUR, 0); countdown.set(Calendar.MINUTE, 0); countdown.set(Calendar.SECOND, 0); countdown.set(Calendar.MINUTE, 0); countdown.add(Calendar.MINUTE, minutes); } // Start the timer public void actionPerformed(ActionEvent e) { h = countdown.get(Calendar.HOUR_OF_DAY); m = countdown.get(Calendar.MINUTE); s = countdown.get(Calendar.SECOND); calendar.add(Calendar.SECOND, -1); Clock.setText("" + h + ":" + df.format(m) + ":" + df.format(s)); count--; if (count == 0) { System.out.println("Time is up!"); refreshTimer.stop(); } } }; refreshTimer = new javax.swing.Timer(10, refreshListener); refreshTimer.setInitialDelay(0); refreshTimer.start(); } }
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Source: https://habr.com/ru/post/1385725/

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