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import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class SwingLengthyOperation extends JPanel {
private JButton searchBn = new JButton("Search");
private JButton cancelBn = new JButton("Cancel Search");
private JLabel balanceL = new JLabel();
private volatile Thread lookupThread;
public SwingLengthyOperation() {
cancelBn.setEnabled(false);
JPanel innerButtonP = new JPanel();
innerButtonP.setLayout(new GridLayout(1, -1, 5, 5));
innerButtonP.add(searchBn);
innerButtonP.add(cancelBn);
JPanel buttonP = new JPanel();
buttonP.setLayout(new FlowLayout(FlowLayout.CENTER));
buttonP.add(innerButtonP);
JLabel balancePrefixL = new JLabel("Account Balance:");
JPanel balanceP = new JPanel();
balanceP.setLayout(new FlowLayout(FlowLayout.CENTER));
balanceP.add(balancePrefixL);
balanceP.add(balanceL);
JPanel northP = new JPanel();
northP.setLayout(new GridLayout(-1, 1, 5, 5));
northP.add(buttonP);
northP.add(balanceP);
setLayout(new BorderLayout());
add(northP, BorderLayout.NORTH);
searchBn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
search();
}
});
cancelBn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
cancelSearch();
}
});
}
private void search() {
ensureEventThread();
searchBn.setEnabled(false);
cancelBn.setEnabled(true);
balanceL.setText("SEARCHING ...");
lookupAsync();
}
private void lookupAsync() {
Runnable lookupRun = new Runnable() {
public void run() {
String bal = lookupBalance();
setBalanceSafely(bal);
}
};
lookupThread = new Thread(lookupRun, "lookupThread");
lookupThread.start();
}
private String lookupBalance() {
try {
Thread.sleep(5000);
return "1,234.56";
} catch (InterruptedException x) {
return "SEARCH CANCELLED";
}
}
private void setBalanceSafely(String newBal) {
final String newBalance = newBal;
Runnable r = new Runnable() {
public void run() {
try {
setBalance(newBalance);
} catch (Exception x) {
x.printStackTrace();
}
}
};
SwingUtilities.invokeLater(r);
}
private void setBalance(String newBalance) {
ensureEventThread();
balanceL.setText(newBalance);
cancelBn.setEnabled(false);
searchBn.setEnabled(true);
}
private void cancelSearch() {
ensureEventThread();
cancelBn.setEnabled(false);
if (lookupThread != null) {
lookupThread.interrupt();
}
}
private void ensureEventThread() {
if (SwingUtilities.isEventDispatchThread()) {
return;
}
throw new RuntimeException("only the event "
+ "thread should invoke this method");
}
public static void main(String[] args) {
JFrame f = new JFrame();
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
f.setContentPane(new SwingLengthyOperation());
f.setSize(400, 150);
f.setVisible(true);
}
}
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