Sizes of frame icons used in Swing

Question

We can use a list to initialise the window icons using Window.setIconImages(List<? extends Image>). What are the different sizes of icons typically used for in a JFrame?

Code

This code turns 64 different sized images (from 16x16, incrementing by 2) into icons for the list.

import java.awt.*; import java.awt.image.BufferedImage; import java.util.ArrayList; import java.util.Vector; import javax.swing.*; import javax.swing.border.EmptyBorder;  public class FrameIconList {      public static BufferedImage getImage(int size, Color color) {         BufferedImage i = new BufferedImage(                 size, size, BufferedImage.TYPE_INT_RGB);          Graphics2D g = i.createGraphics();          g.setColor(color);         g.fillRect(0, 0, size, size);         g.setColor(Color.BLACK);         int off = (size>17 ? 3 : 1);         if (off>1) g.drawRect(0, 0, size-1, size-1);         g.drawString("" + size, off, size-off);          g.dispose();          return i;     }      public static void main(String[] args) {         final Color[] colors = {             Color.GREEN,             Color.RED,             Color.YELLOW,             Color.WHITE,             Color.CYAN,             Color.MAGENTA,             Color.PINK,             Color.ORANGE         };          int s = 64;         final int[] sizes = new int[s];                  for (int ii=0; ii<sizes.length; ii++) {             sizes[ii] = 16+(ii*2);         }          Runnable r = new Runnable() {              @Override             public void run() {                 // the GUI as seen by the user (without frame)                 JPanel gui = new JPanel(new BorderLayout());                 gui.setBorder(new EmptyBorder(2, 3, 2, 3));                 gui.setBackground(Color.WHITE);                                  ArrayList<BufferedImage> images = new ArrayList<BufferedImage>();                 Vector<ImageIcon> icons = new Vector<ImageIcon>();                 for (int ii=0; ii< sizes.length; ii++) {                     BufferedImage bi = getImage(                             sizes[ii],                              colors[ii%colors.length]);                     images.add(bi);                     ImageIcon imi = new ImageIcon(bi);                     icons.add(imi);                 }                 JList list = new JList(icons);                 list.setVisibleRowCount(6);                 gui.add(new JScrollPane(list));                  JFrame f = new JFrame("Icon size usage");                 f.setIconImages(images);                 f.add(gui);                 // Ensures JVM closes after frame(s) closed and                 // all non-daemon threads are finished                 f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);                 // See http://stackoverflow.com/a/7143398/418556 for demo.                 f.setLocationByPlatform(true);                  // ensures the frame is the minimum size it needs to be                 // in order display the components within it                 f.pack();                 // should be done last, to avoid flickering, moving,                 // resizing artifacts.                 f.setVisible(true);             }         };         // Swing GUIs should be created and updated on the EDT         // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html         SwingUtilities.invokeLater(r);     } } 

Answer 1

Typical views for this Windows 7 based PC

Note: @bobbel reports the same sizes are used for Windows 10.

Frame - 20x20

Task Bar - 40x40 in task bar itself, hover app shows 20x20

Windows+Tab - 20x20

Alt+Tab - 40x40 in lower right, shrunken 20x20 in upper left.

Task Manager - 20x20