[英]How do I visibly change the contents of my JScrollPane each time I call the ActionListener?
每次調用Action Listener時,我都希望這個JScrollPane將其列表更改為完全不同的列表。 我不完全確定如何做到這一點。 我已經嘗試更改JList,重新繪制ScrollPane並重新驗證它,但它沒有帶來預期的效果。 我寫了一個可編輯的迷你程序,在這里解釋了我的問題:
import javax.swing.*;
import javax.swing.border.TitledBorder;
import java.awt.*;
import java.awt.event.*;
import java.sql.SQLException;
@SuppressWarnings("serial")
public class TestFrame extends JFrame {
public final Dimension SCROLL_PANE_DIMENSION = new Dimension(200, 100);
private JComboBox<String> comboNames;
private JPanel panel = new JPanel();
private JList<String> availableList;
private JScrollPane theScrollPane;
private boolean string1Used = true;
String[] strings = { "Aaardvark", "Adam", "Alms" };
String[] strings2 = { "Bad", "Bugs", "Bunny" };
public static void main(String[] args){
try {
TestFrame frame = new TestFrame();
frame.setVisible(true);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public TestFrame() throws SQLException {
String[] comboStrings = { "Doesn't", "matter", "here" };
this.setSize(300,200);
availableList = new JList<String>(strings);
theScrollPane = new JScrollPane(availableList);
theScrollPane = new JScrollPane(availableList);
theScrollPane.setPreferredSize(SCROLL_PANE_DIMENSION);
theScrollPane.setSize(SCROLL_PANE_DIMENSION);
theScrollPane.setBorder(BorderFactory.createTitledBorder(
BorderFactory.createEtchedBorder(), "Sub Conditions",
TitledBorder.CENTER, 0));
availableList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
availableList.setSelectedIndex(0);
availableList.setVisibleRowCount(5);
availableList.setSize(SCROLL_PANE_DIMENSION);
comboNames = new JComboBox<String>(comboStrings);
comboNames.addActionListener(new ConditionComboListener());
panel = new JPanel();
this.add(panel);
panel.add(comboNames);
panel.add(theScrollPane);
}
private class ConditionComboListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent arg0) {
refreshSubConditionList();
}
private void refreshSubConditionList() {
if (string1Used) {
System.out.println("Switching to Strings2");
availableList = new JList<String>(strings2);
string1Used = false;
} else{
System.out.println("Switching to Strings");
availableList = new JList<String>(strings);
string1Used = true;
}
theScrollPane = new JScrollPane(availableList);
theScrollPane.revalidate();
theScrollPane.repaint();
}
}
}
在這個例子中,每當我更改JComboBox中的內容時,我希望JScrollPane內的列表在數組strings1和strings2之間切換。 我也希望這個改變是可見的,因為我改變了組合框中的內容,而不是以后。 正如您從編譯的代碼中看到的那樣,它並沒有那么好用。 我究竟做錯了什么? 為什么我不希望它改變列表?
創建新的滾動窗格不會將滾動窗格添加到面板。
無論如何,沒有必要繼續創建一個新的滾動窗格。 只需更改滾動窗格中顯示的組件:
//theScrollPane = new JScrollPane(availableList);
//theScrollPane.revalidate();
//theScrollPane.repaint();
theScrollPane.setViewportView(availableList);
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