In this tutorial we shall show you how to use an ActionListener in order to create a Multilistener component in a Java Desktop application. You may find this useful when you want some of your components to behave in the same way under certain circumstances.
In short, all you have to do in order to create a MultiListener component is:
- Create a new
ActionListenerinstance. - Override the
actionPerformedmethod to customize the handling of an event. - Use the
addActionListenermethod to add the aboveActionListenerto a number of components you to monitor.
Let’s see the code snippet that follows:
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 | package com.javacodegeeks.snippets.desktop;import java.awt.Color;import java.awt.Dimension;import java.awt.GridBagConstraints;import java.awt.GridBagLayout;import java.awt.Insets;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.BorderFactory;import javax.swing.JButton;import javax.swing.JComponent;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTextArea;public class Main extends JPanel implements ActionListener { JButton b1, b2; JTextArea topText; JTextArea bottomText; final static String nl = "n"; public Main() { super(new GridBagLayout()); GridBagLayout gridbaglayout = (GridBagLayout) getLayout(); GridBagConstraints constraints = new GridBagConstraints(); JLabel jLabel = null; constraints.fill = GridBagConstraints.BOTH; constraints.gridwidth = GridBagConstraints.REMAINDER; jLabel = new JLabel("MultiListener heard:"); gridbaglayout.setConstraints(jLabel, constraints); add(jLabel); constraints.weighty = 1.0; topText = new JTextArea(); topText.setEditable(false); JScrollPane topScrollPane = new JScrollPane(topText); Dimension preferredSize = new Dimension(220, 85); topScrollPane.setPreferredSize(preferredSize); gridbaglayout.setConstraints(topScrollPane, constraints); add(topScrollPane); constraints.weightx = 0.0; constraints.weighty = 0.0; jLabel = new JLabel("Eve heard:"); gridbaglayout.setConstraints(jLabel, constraints); add(jLabel); constraints.weighty = 1.0; bottomText = new JTextArea(); bottomText.setEditable(false); JScrollPane bottomScrollPane = new JScrollPane(bottomText); bottomScrollPane.setPreferredSize(preferredSize); gridbaglayout.setConstraints(bottomScrollPane, constraints); add(bottomScrollPane); constraints.weightx = 1.0; constraints.weighty = 0.0; constraints.gridwidth = 1; constraints.insets = new Insets(10, 10, 0, 10); b1 = new JButton("Jiber Jaber"); gridbaglayout.setConstraints(b1, constraints); add(b1); constraints.gridwidth = GridBagConstraints.REMAINDER; b2 = new JButton("Be serious"); gridbaglayout.setConstraints(b2, constraints); add(b2); b1.addActionListener(this); b2.addActionListener(this); b2.addActionListener(new ManInTheMiddle(bottomText)); setPreferredSize(new Dimension(600, 600)); setBorder(BorderFactory.createCompoundBorder(BorderFactory.createMatteBorder(1, 1, 2, 2, Color.black), BorderFactory.createEmptyBorder(5, 5, 5, 5))); } @Override public void actionPerformed(ActionEvent event) { topText.append(event.getActionCommand() + nl); topText.setCaretPosition(topText.getDocument().getLength()); } private static void dispGUI() { JFrame.setDefaultLookAndFeelDecorated(true); JFrame frame = new JFrame(""); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JComponent newContentPane = new Main(); newContentPane.setOpaque(true); frame.setContentPane(newContentPane); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() {@Overridepublic void run() { dispGUI();} }); }}class ManInTheMiddle implements ActionListener { JTextArea mText; public ManInTheMiddle(JTextArea text) { mText = text; } @Override public void actionPerformed(ActionEvent event) { mText.append(event.getActionCommand() + Main.nl); mText.setCaretPosition(mText.getDocument().getLength()); }} |
This was an example on how to create a Multilistener component in Java.
