checkbox<\/code> is to present whether an item has been selected or unselected. In Java swing, JCheckBox<\/code> is the component to fulfill this function. Different actions could be performed, and different states could also be displayed to the users, if we add action listener or action handler to the checkbox<\/code>.<\/p>\nIn Java swing, JCheckBox<\/code> is inherited from AbstractButton<\/code> and JToggleButton<\/code>. It inherits all the methods from its parent classes. It could be constructed through following constructors:<\/p>\n\n- JCheckBox(): creates an checkbox without text nor icon<\/li>\n
- JCheckBox(Action e): creates an checkbox where properties are taken from the provided action<\/li>\n
- JCheckBox(Icon icon): creates an checkbox with an icon<\/li>\n
- JCheckBox(Icon icon, boolean selected): creates an checkbox with an icon and specifies whether this icon has been selected or not<\/li>\n
- JCheckBox(String text): creates an checkbox with text<\/li>\n
- JCheckBox(String text, boolean selected):\u00a0creates an checkbox with text\u00a0and specifies whether this text has been selected or not<\/li>\n
- JCheckBox(String text, Icon icon):\u00a0creates an checkbox with an icon and text<\/li>\n
- JCheckBox(String text,\u00a0Icon icon, boolean selected):\u00a0\u00a0creates an checkbox with text and icon, and specifies whether these two have been selected or not<\/li>\n<\/ul>\n
Further detailed information about the JCheckBox<\/code> could be referred to the official Oracle documents<\/a>.<\/p>\n2. Examples on java swing checkbox<\/h2>\n
For the following example parts on JCheckBox<\/code>, Java 8 and Eclipse IDE (version Mars 4.5.0) are used.<\/p>\n2.1 Simple example of java swing checkbox<\/h3>\n
In this example, five JCheckBox<\/code> are created, added to the panel and frame, with the title to be set to “Fruits”. Five different fruits are named by “Apple”, “Banana”, “Grape”, “Orange” and “Pear”. Then these can be selected by the checkbox<\/code>.<\/p>\nBelow is the Java code for this example:<\/p>\n
simpleCheckbox.java<\/em><\/span><\/p>\npackage javaCodeGeeks;\r\n\r\n\/*\r\n * A simple swing checkbox example with different constructors\r\n *\/\r\n\r\nimport javax.swing.JFrame;\r\nimport javax.swing.JPanel;\r\nimport javax.swing.BorderFactory;\r\nimport javax.swing.JCheckBox;\r\n\r\npublic class simpleCheckbox {\r\n\r\n\tpublic static void main(String[] args) {\r\n\t\t\/\/ Create and set up a frame window\r\n\t\tJFrame.setDefaultLookAndFeelDecorated(true);\r\n\t\tJFrame frame = new JFrame(\"Simple checkbox demo\");\r\n\t\tframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);\r\n\t\t\r\n\t\t\/\/ Define the panel to hold the checkbox\t\r\n\t\tJPanel panel = new JPanel();\r\n\t\t\r\n\t\t\/\/ Create checkbox with different constructors\r\n\t\tJCheckBox checkbox1 = new JCheckBox(\"Apple\", true);\r\n\t\tJCheckBox checkbox2 = new JCheckBox(\"Banana\");\t\t\r\n\t\tJCheckBox checkbox3 = new JCheckBox(\"Grape\", true);\r\n\t\tJCheckBox checkbox4 = new JCheckBox(\"Orange\");\r\n\t\tJCheckBox checkbox5 = new JCheckBox(\"Pear\", true);\r\n\t\t\r\n\t\t\/\/ Set up the title for the panel\r\n\t\tpanel.setBorder(BorderFactory.createTitledBorder(\"Fruits\"));\r\n\t\t\r\n\t\t\/\/ Add the checkbox into the panels \r\n\t\tpanel.add(checkbox1);\r\n\t\tpanel.add(checkbox2);\r\n\t\tpanel.add(checkbox3);\r\n\t\tpanel.add(checkbox4);\r\n\t\tpanel.add(checkbox5);\r\n\t\t\r\n\t\t\/\/ Add the panel into the frame\r\n\t\tframe.add(panel);\r\n\t\t\r\n\t\t\/\/ Set the window to be visible as the default to be false\r\n\t\tframe.pack();\r\n\t\tframe.setVisible(true);\r\n\r\n\t}\r\n\r\n}\r\n<\/pre>\nRun this code, and following result should show up:
<\/div> <\/div><\/p>\n![\"simpleCheckbox\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/simpleCheckbox.jpg\")
<\/a>simple Checkbox demo<\/figcaption><\/figure><\/p>\nAs we can see from the above figure, “Apple”, “Grape” and “Pear” are selected automatically, while “Banana” and “Orange” not. The reason for this is we have set the three fruits to be selected, while the other two not. The following code could explain the difference.<\/p>\n
\t\tJCheckBox checkbox1 = new JCheckBox(\"Apple\", true);\r\n\t\tJCheckBox checkbox2 = new JCheckBox(\"Banana\");\r\n<\/pre>\n2.2 Other settings on checkbox<\/h3>\n
As we\u2019ve described in introduction part, that JCheckBox<\/code> is inherited from AbstractButton<\/code> and JToggleButton<\/code>, we can have different settings on checkbox<\/code>.<\/p>\nFor example, we can set font for different checkbox<\/code> with the code similar to the following:<\/p>\ncheckbox1.setFont(new java.awt.Font(\"Arial\", Font.BOLD, 18));\r\n<\/pre>\nIn this example, we’ve set the font for the checkbox<\/code> “Apple” to be “Arial” with the font to be 18 and bolded. The effect of this setting can be shown as below:<\/p>\n![\"font\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/font.jpg\")
<\/a>Font setting on checkbox<\/figcaption><\/figure><\/p>\nAlso, we can set the background and foreground with different colors. For example, we can set the color of checkbox<\/code> “Banana” to be “RED” with the following code:<\/p>\ncheckbox2.setForeground(Color.RED);\r\n<\/pre>\nThe result of this setting is shown below:<\/p>\n
![\"color\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/color.jpg\")
<\/a>Color setting on checkbox<\/figcaption><\/figure><\/p>\nLastly, we can set the mnemonic key by specifying the key code defined in java.wt.event.KeyEvent<\/code>. For instance, keyboard ‘A’ could be set to mnemonic key by following code:<\/p>\n\t\tcheckbox1.setMnemonic(KeyEvent.VK_A);\r\n\t\tcheckbox1.setSelected(true);\r\n<\/pre>\nThe result for this setting is that you can use the keyboard ‘alt’ and ‘A’ to select or unselect the specified checkbox<\/code>. Figure below shows this effect:<\/p>\n![\"mnemonic\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/mnemonic.jpg\")
<\/a>Mnemonic setting on checkbox<\/figcaption><\/figure><\/p>\n2.3 Checkbox with event listener<\/h3>\n
For checkbox<\/code>, the more common usage should be combining it with event listener. With the event listener added, the checkbox<\/code> can act different actions.<\/p>\nIn the following example, we have different names (“Alex”, “Jessica”, “Lily”, “Steven”) on panel1. When we click any name, the output panel shows that the name is selected. However, when we unselect the name, the output panel shows that the name is unselected.<\/p>\n
Below is the Java code for this example:<\/p>\n
checkboxWithEvent.java<\/em><\/span><\/p>\npackage javaCodeGeeks;\r\n\r\n\/*\r\n * A checkbox example with event listener\r\n *\/\r\n\r\nimport javax.swing.JFrame;\r\nimport javax.swing.JLabel;\r\nimport javax.swing.JPanel;\r\nimport javax.swing.BorderFactory;\r\nimport javax.swing.JCheckBox;\r\n\r\nimport java.awt.GridLayout;\r\nimport java.awt.event.ItemEvent;\r\nimport java.awt.event.ItemListener;\r\n\r\npublic class checkboxWithEvent {\t\r\n\t\/\/ Create different checkbox\r\n\tpublic static JCheckBox checkbox1 = new JCheckBox(\"Alex\");\r\n\tpublic static JCheckBox checkbox2 = new JCheckBox(\"Jessica\");\r\n\tpublic static JCheckBox checkbox3 = new JCheckBox(\"Lily\");\t\t\r\n\tpublic static JCheckBox checkbox4 = new JCheckBox(\"Steven\");\r\n\r\n\tpublic static void main(String[] args) {\r\n\t\t\/\/ Create and set up a frame window\r\n\t\tJFrame.setDefaultLookAndFeelDecorated(true);\r\n\t\tJFrame frame = new JFrame(\"Checkbox with event listener\");\r\n\t\tframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);\r\n\t\t\r\n\t\t\/\/ Define the panel to hold the checkbox\t\r\n\t\tJPanel panel1 = new JPanel();\r\n\t\tJPanel panel2 = new JPanel();\r\n\t\tJLabel msg = new JLabel(\"\", JLabel.CENTER);\r\n\t\t\t\r\n\t\t\/\/ Set up the title for the panel\r\n\t\tpanel1.setBorder(BorderFactory.createTitledBorder(\"Name\"));\t\r\n\t\tpanel2.setBorder(BorderFactory.createTitledBorder(\"Output\"));\t\t\r\n\t\t\r\n\t\t\/\/ Add the checkbox into the panels \t\r\n\t\tpanel1.add(checkbox1);\r\n\t\tpanel1.add(checkbox2);\r\n\t\tpanel1.add(checkbox3);\r\n\t\tpanel1.add(checkbox4);\r\n\t\t\r\n\t\tpanel2.add(msg);\r\n\t\t\r\n\t\t\/\/ Add action listener\r\n\t\tcheckbox1.addItemListener(new ItemListener() {\r\n\t\t\tpublic void itemStateChanged(ItemEvent e) {\r\n\t\t\t\tif (e.getStateChange() == 1) {\r\n\t\t\t\t\tmsg.setText(\"Alex is selected\");\r\n\t\t\t\t} else {\r\n\t\t\t\t\tmsg.setText(\"Alex is unselected\");\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\t});\r\n\r\n\t\tcheckbox2.addItemListener(new ItemListener() {\r\n\t\t\tpublic void itemStateChanged(ItemEvent e) {\r\n\t\t\t\tif (e.getStateChange() == 1) {\r\n\t\t\t\t\tmsg.setText(\"Jessica is selected\");\r\n\t\t\t\t} else {\r\n\t\t\t\t\tmsg.setText(\"Jessica is unselected\");\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\t});\r\n\t\t\r\n\t\tcheckbox3.addItemListener(new ItemListener() {\r\n\t\t\tpublic void itemStateChanged(ItemEvent e) {\r\n\t\t\t\tif (e.getStateChange() == 1) {\r\n\t\t\t\t\tmsg.setText(\"Lily is selected\");\r\n\t\t\t\t} else {\r\n\t\t\t\t\tmsg.setText(\"Lily is unselected\");\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\t});\r\n\t\t\r\n\t\tcheckbox4.addItemListener(new ItemListener() {\r\n\t\t\tpublic void itemStateChanged(ItemEvent e) {\r\n\t\t\t\tif (e.getStateChange() == 1) {\r\n\t\t\t\t\tmsg.setText(\"Steven is selected\");\r\n\t\t\t\t} else {\r\n\t\t\t\t\tmsg.setText(\"Steven is unselected\");\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\t});\r\n\t\t\r\n\t\t\/\/ Add the panel into the frame\r\n\t\tframe.setLayout(new GridLayout(2, 1));\r\n\t\tframe.add(panel1);\r\n\t\tframe.add(panel2);\r\n\t\t\r\n\t\t\/\/ Set the window to be visible as the default to be false\r\n\t\tframe.pack();\r\n\t\tframe.setVisible(true);\r\n\t}\r\n\t\r\n}\r\n<\/pre>\nWhen we run this code, we can see the result below with nothing in the output panel.<\/p>\n
![\"output\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/output.jpg\")
<\/a>Output with nothing<\/figcaption><\/figure><\/p>\nHowever, after we select the checkbox<\/code> of Alex, the output shows that Alex is selected as below:<\/p>\n
![\"selected\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/selected.jpg\")
<\/a>![\"unselected\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/unselected.jpg\")
<\/a>