我有一個JScrollPane,它包含一個JTextArea。當窗口最小化然後恢復時,JScrollPane會自行崩潰。請注意,只有在JTextArea中的文本超出JTextArea的給定寬度和/或高度(即出現水平或垂直滾動條)時纔會發生擠壓。JScrollPane窗口縮小縮小最小化
這個問題在這裏:JScrollpane loses size after minimize帶來了同樣的問題,但這個問題從來沒有解決過,除了向JScrollPane添加weightx,weighty和fill約束外,我已經開始了。
下面是一個演示問題的簡單示例。在窗口最小化和恢復後,如何讓JScrollPane保持其大小?
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.ExecutionException;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.border.EtchedBorder;
public class GUITest implements ActionListener {
JButton button = new JButton("Button");
JTextArea textArea = new JTextArea();
SwingWorker<String, String> mySwingWorker = null;
public static void main(String[] args) throws IOException {
GUITest tracer = new GUITest();
}
public GUITest() throws IOException {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
try {
createAndShowGUI();
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
public void createAndShowGUI() throws IOException {
JFrame frame = new JFrame("GUI Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new GridBagLayout());
GridBagConstraints mainPanelConstraints = new GridBagConstraints();
mainPanelConstraints.gridx = 0;
mainPanelConstraints.gridy = 0;
mainPanelConstraints.fill = GridBagConstraints.BOTH;
button.addActionListener(this);
mainPanel.add(button, mainPanelConstraints);
mainPanelConstraints.gridx = 0;
mainPanelConstraints.gridy = 1;
mainPanelConstraints.fill = GridBagConstraints.BOTH;
mainPanel.add(buildTextAreaPanel(), mainPanelConstraints);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setVisible(true);
}
private JPanel buildTextAreaPanel() {
JPanel textAreaPanel = new JPanel();
textAreaPanel.setLayout(new GridBagLayout());
GridBagConstraints textAreaPanelConstraints = new GridBagConstraints();
textAreaPanel.setBorder(BorderFactory.createTitledBorder(new EtchedBorder(EtchedBorder.RAISED), "TextArea"));
textArea.setColumns(30);
textArea.setRows(15);
textArea.setEditable(false);
JScrollPane textAreaScrollPane = new JScrollPane(textArea);
textAreaScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
textAreaScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
textAreaPanelConstraints.gridx = 0;
textAreaPanelConstraints.gridy = 0;
textAreaPanelConstraints.weightx = 1.0;
textAreaPanelConstraints.weighty = 1.0;
textAreaPanelConstraints.fill = GridBagConstraints.BOTH;
textAreaPanel.add(textAreaScrollPane, textAreaPanelConstraints);
return textAreaPanel;
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == button) {
mySwingWorker = new MySwingWorker();
mySwingWorker.execute();
}
}
private class MySwingWorker extends SwingWorker<String, String> {
public String doInBackground() throws Exception {
for (int i = 0; i < textArea.getRows(); i++) {
publish("text\n");
}
publish("more text\n");
return "Done.";
}
public void process(List<String> chunks) {
for (String msg : chunks) {
textArea.append(msg);
}
}
public void done() {
try {
String msg = get();
textArea.append("\n" + msg);
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
我可以看到這會產生所需的行爲,但我不明白爲什麼修改容器的權重值會影響其子組件的大小行爲。你可以解釋嗎? – FalconRunner11
編輯上述評論:由「子組件」我其實是指「孫子組件」。 textAreaScrollPane提供了錯誤的行爲,駐留在textAreaPanel中,然後textAreaPanel駐留在mainPanel中。那麼,如何改變mainPanel的佈局屬性對textAreaScrollPane有直接的影響? – FalconRunner11
weightx和weighty約束決定組件是否展開以填充其父項。如果文本區域面板拉伸以填充mainPanel,則無關緊要,除非mainPanel自身伸展以填充窗口。 – VGR