我想在我的节目JButton
被点击时看到Jlabel
,但它不起作用!
public class d5 extends JFrame implements ActionListener {
JButton showButton;
static JLabel[] lbl;
JPanel panel;
public d5() {
showButton = new JButton("Show");
showButton.addActionListener(this);
add(showButton, BorderLayout.PAGE_START);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400, 500);
setLocation(300, 30);
setVisible(true);
}
public JPanel mypanel() {
panel = new JPanel(new FlowLayout(FlowLayout.LEFT));
lbl = recordsLabel();
for (JLabel jLabel : lbl) {
panel.add(jLabel);
}
return panel;
}
public static void main(String[] args) {
new d5();
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == showButton) {
add(mypanel(), BorderLayout.PAGE_START);
setVisible(true);
System.out.println("show button clicked");
}
}
public JLabel[] recordsLabel() {
ArrayList<String> lableList = new ArrayList<>();
lableList.add("one");
lableList.add("two");
lableList.add("three");
Object[] arrayResultRow = lableList.toArray();
int rows = 3;
lbl = new JLabel[rows];
for (int i = 0; i < rows; i++) {
lbl[i] = new JLabel(arrayResultRow[i].toString());
}
return lbl;
}
}
作为@nicecow注释,您已经将add(showButton, BorderLayout.PAGE_START);
放在了与面板相同的位置。在同一位置只能添加一个零部件。
此外,调用validate也不错。
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == showButton) {
add(mypanel(), BorderLayout.PAGE_START); // set another position or remove previous component here
validate();
System.out.println("show button clicked");
}
}
顺便说一句,我不建议在JFrame
类中实现ActionListener
,也不需要扩展JFrame
public class D5 {
private JFrame frame;
.
. // is some part in constrcutor
.
showButton.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent evt){
frame.add(mypanel(),BorderLayout.PAGE_START);
frame.validate();
}
})
}