我正在努力在正在开发的程序中创建一个简单的动作事件。 该程序，当我右键单击它时必须添加新的JComboBoxes。而且有效。 它必须将这些JcomboBox中的文本添加到字符串数组列表中。而且有效。 现在的问题。也许用户想删除一个JComboBox，所以它将从JComboBox数组中删除，然后从字符串数组中删除文本，最后从屏幕中删除文本。它已从两个阵列中正确删除，但仅从屏幕中删除了一次。这是为什么？我添加了validate和repaint方法，但它只会删除“可视” JComboBox的最后一行，而不会“看到”那里的其他行。我究竟做错了什么？ 程序内部进行了一些绘画检查，仅用于调试目的，因此我知道除了从JPanel中删除以外，其他所有方法都有效。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class TestingGround
{
Toolkit toolkit;
JFrame frame;
JPopupMenu menu;
private ArrayList <JComboBox> projectLineComboBoxList;
private String [] productLineDefinedList = {"-","A","B","C" ,"D","E","F","G", "H", "I", "J","K","L", "M"};
private ArrayList userOptionList;
private JComboBox productLineBox;
int countAddClicks;
public TestingGround()
{
frame = new JFrame("Testing ground area");
centerToScreen();
menu = new JPopupMenu();
JMenuItem addRow = new JMenuItem("Add ComboBox");
JMenuItem removeRow = new JMenuItem("Remove ComboBox");
JPanel panel = new JPanel();
JPanel mainGridPanel = new JPanel();
mainGridPanel.setLayout(new GridLayout(0,2));
mainGridPanel.setBorder(BorderFactory.createLineBorder(Color.red));
panel.add(mainGridPanel);
userOptionList = new ArrayList();
projectLineComboBoxList = new ArrayList();
JButton button = new JButton("save state");
productLineBox = new JComboBox(productLineDefinedList);
countAddClicks =0;
panel.add(button);
// ACTION LISTENERS
addRow.addActionListener(new ActionListener(){ // Right click to add JComboBoxes to the screen
public void actionPerformed(ActionEvent event) {
System.out.println("Initial click is: " + countAddClicks);
productLineBox = new JComboBox(productLineDefinedList); // add a new JComboBox
projectLineComboBoxList.add(countAddClicks,productLineBox); // add this JComboBox to the JComboBox Array List
countAddClicks++;
System.out.println("After click is: " + countAddClicks);
mainGridPanel.add(productLineBox);
mainGridPanel.repaint();
mainGridPanel.revalidate();
}
});
// Problem is right here!
removeRow.addActionListener(new ActionListener(){
public void actionPerformed (ActionEvent event) {
countAddClicks--;
System.out.println("After removal click is: " + countAddClicks);
projectLineComboBoxList.remove(projectLineComboBoxList.size()-1); // delete from the Array of JComboBoxes
userOptionList.remove(userOptionList.size()-1);
mainGridPanel.remove(productLineBox); // THIS action removes only the last ComboBox from the screen, and does not "see" the other ones that I want to remove. It should remove one by one from the screen.
mainGridPanel.revalidate();
mainGridPanel.repaint();
}
});
button.addActionListener (new ActionListener() {
public void actionPerformed(ActionEvent e) {
userOptionList.clear();
for (int i=0; i<projectLineComboBoxList.size(); i++) {
JComboBox tempBoxxx = projectLineComboBoxList.get(i);
String tzz = tempBoxxx.getSelectedItem().toString();
userOptionList.add(tempBoxxx.getSelectedItem().toString()); // Add the text to the String Array List
}
System.out.println();
System.out.println("The length of the JComboBox Array is: " + projectLineComboBoxList.size() );
System.out.println("The content of the String array is: " + userOptionList );
System.out.println("The size of the String array is: " + userOptionList.size());
System.out.println();
}
});
// Cand dau click din butonul cel mai din dreapta (3) se deschide menium popup
frame.addMouseListener(new MouseAdapter() {
public void mouseReleased(MouseEvent event) {
if (event.getButton() == event.BUTTON3) {
menu.show(event.getComponent(), event.getX(),event.getY());
}
}
});
menu.add(addRow);
menu.add(removeRow);
frame.add(panel);
frame.setVisible(true);
}
public void centerToScreen()
{
frame.setSize(700,600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("A Popup Menu");
toolkit = frame.getToolkit();
Dimension size = toolkit.getScreenSize();
frame.setLocation((size.width-frame.getWidth())/2, (size.height-frame.getHeight())/2);
}
public static void main(String[]args){
new TestingGround();
}
}
答案 0 :(得分：1)
我已经尝试过您的代码，但总是在行中出现异常
userOptionList.remove(userOptionList.size()-1);
因为给定列表始终为空。所以我删除了它。
要解决删除问题，您只需将最后删除的组合框保存在变量productLineBox中。因此，您需要替换行
projectLineComboBoxList.remove(projectLineComboBoxList.size()-1); // delete from the Array of JComboBoxes
按行
productLineBox = projectLineComboBoxList.remove(projectLineComboBoxList.size()-1); // delete from the Array of JComboBoxes
在这种情况下，所有功能都可以正常工作，您可以删除所有添加的组合框。
这是我重构的完整代码
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.SwingUtilities;
public class TestingGround {
private static final String[] PRODUCT_LINE_LIST = {"-", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M"};
private final List<JComboBox<String>> projectLineComboBoxList;
private final List<String> userOptionList;
private int countAddClicks;
public TestingGround() {
JFrame frame = new JFrame("Testing ground area");
centerToScreen(frame);
JPopupMenu menu = new JPopupMenu();
JMenuItem addRow = new JMenuItem("Add ComboBox");
JMenuItem removeRow = new JMenuItem("Remove ComboBox");
JPanel panel = new JPanel();
JPanel mainGridPanel = new JPanel();
mainGridPanel.setLayout(new GridLayout(0, 2));
mainGridPanel.setBorder(BorderFactory.createLineBorder(Color.red));
panel.add(mainGridPanel);
userOptionList = new ArrayList<>();
projectLineComboBoxList = new ArrayList<>();
JButton button = new JButton("save state");
countAddClicks = 0;
panel.add(button);
// ACTION LISTENERS
addRow.addActionListener(new ActionListener() { // Right click to add JComboBoxes to the screen
@Override
public void actionPerformed(ActionEvent event) {
System.out.println("Initial click is: " + countAddClicks);
JComboBox<String> productLineBox = new JComboBox<>(PRODUCT_LINE_LIST); // add a new JComboBox
projectLineComboBoxList.add(countAddClicks, productLineBox); // add this JComboBox to the JComboBox Array List
countAddClicks++;
System.out.println("After click is: " + countAddClicks);
mainGridPanel.add(productLineBox);
mainGridPanel.repaint();
mainGridPanel.revalidate();
}
});
// Problem is right here!
removeRow.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent event) {
countAddClicks--;
System.out.println("After removal click is: " + countAddClicks);
// delete from the Array of JComboBoxes
JComboBox<String> productLineBox = projectLineComboBoxList.remove(projectLineComboBoxList.size() - 1);
// userOptionList.remove(userOptionList.size() - 1);
mainGridPanel.remove(productLineBox); // THIS action removes only the last ComboBox from the screen, and does not "see" the
// other ones that I want to remove. It should remove one by one from the screen.
mainGridPanel.revalidate();
mainGridPanel.repaint();
}
});
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
userOptionList.clear();
for (int i = 0; i < projectLineComboBoxList.size(); i++) {
JComboBox<String> tempBoxxx = projectLineComboBoxList.get(i);
String tzz = tempBoxxx.getSelectedItem().toString();
userOptionList.add(tzz); // Add the text to the String Array List
}
System.out.println();
System.out.println("The length of the JComboBox Array is: " + projectLineComboBoxList.size());
System.out.println("The content of the String array is: " + userOptionList);
System.out.println("The size of the String array is: " + userOptionList.size());
System.out.println();
}
});
((JComponent) frame.getContentPane()).setComponentPopupMenu(menu);
menu.add(addRow);
menu.add(removeRow);
frame.add(panel);
frame.setVisible(true);
}
private void centerToScreen(JFrame frame) {
frame.setSize(700, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("A Popup Menu");
frame.setLocationRelativeTo(null);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(TestingGround::new);
}
}