使 JOptionPane 消息对话框在渲染后消失
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【中文标题】使 JOptionPane 消息对话框在渲染后消失【英文标题】：Make JOptionPane message dialog box dissappear after rendering 【发布时间】：2013-09-21 09:52:19 【问题描述】：我正在构建一个需要用户输入的简单 JFrame GUI。如果用户单击提交按钮，它会检查输入，然后呈现一条 JOptionPane 消息，告诉用户完全填写表单，或者告诉用户表单已提交并关闭程序。问题是，如果用户留下空白字段，则消息对话框会呈现，并且仅在您尝试关闭它时才会增加循环计数，并且不允许用户返回 JFrame 以将输入应用于表单。
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.JOptionPane;
import java.awt.*;
import java.util.Scanner.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
*
* @author joel.ramsey
*/
public class JRStarPhase5 extends JFrame
public static void main (String [] args) throws IOException
JFrame window = new JRStarPhase5();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
//end main method
private boolean validationError;
private final JTextField fNameInput;
private final JTextField miInput;
private final JTextField lNameInput;
private final JTextField productChoiceInput;
private final JTextField licenseQuantityInput;
private final JTextField streetAddressInput;
private final JTextField cityInput;
private final JTextField stateInput;
private final JTextField zipInput;
private final JTextField phoneInput;
//constructor for JFrame
public JRStarPhase5()
setTitle("JRStar Star Gaze Order Processing");
setSize (800,800);
Container pane = getContentPane();
GridLayout grid = new GridLayout(0,2);
pane.setLayout(grid);
JLabel fNameLabel = new JLabel ("First name:");
JLabel mi = new JLabel ("Middle initial:");
JLabel lNameLabel = new JLabel ("Last name:");
JLabel productChoice = new JLabel ("Star Gaze version:");
JLabel licenseQuantity = new JLabel ("License quantity:");
JLabel streetAddress = new JLabel ("Street address:");
JLabel city = new JLabel ("City:");
JLabel state = new JLabel ("State abbrev:");
JLabel zip = new JLabel ("Zip code:");
JLabel phone = new JLabel ("Phone Number:");
this.fNameInput = new JTextField(15);
this.miInput = new JTextField (1);
this.lNameInput = new JTextField (15);
this.productChoiceInput = new JTextField (1);
this.licenseQuantityInput = new JTextField (2);
this.streetAddressInput = new JTextField (20);
this.cityInput = new JTextField (20);
this.stateInput = new JTextField (2);
this.zipInput = new JTextField (5);
this.phoneInput = new JTextField (10);
//add as last buttons
JButton submit = new JButton("Submit");
SubmitButtonHandler sbh = new SubmitButtonHandler();
submit.addActionListener(sbh);
JButton clear = new JButton("Clear");
ClearButtonHandler cbh = new ClearButtonHandler();
clear.addActionListener(cbh);
pane.add(fNameLabel);
pane.add(fNameInput);
pane.add(mi);
pane.add(miInput);
pane.add(lNameLabel);
pane.add(lNameInput);
pane.add(productChoice);
pane.add(productChoiceInput);
pane.add(licenseQuantity);
pane.add(licenseQuantityInput);
pane.add(streetAddress);
pane.add(streetAddressInput);
pane.add(city);
pane.add(cityInput);
pane.add(state);
pane.add(stateInput);
pane.add(zip);
pane.add(zipInput);
pane.add(phone);
pane.add(phoneInput);
//add last
pane.add(submit);
pane.add(clear);
//end constructor
private class SubmitButtonHandler implements ActionListener
public void actionPerformed(ActionEvent e)
validationError = (fNameInput.getText().equals("")||
miInput.getText().equals("")||
lNameInput.getText().equals("")||
streetAddressInput.getText().equals("")||
cityInput.getText().equals("")||
stateInput.getText().equals("")||
zipInput.getText().equals("")||
phoneInput.getText().equals(""));
for (int n=1; n<3; n++)
if (validationError)
if (n == 3)
System.exit(0);
JOptionPane.showMessageDialog(null,"Please complete each field within the order form.");
else break;
if (validationError = false)
JOptionPane.showMessageDialog(null,"Your order has been submitted!");
System.exit(0);
//end submit
private class ClearButtonHandler implements ActionListener
public void actionPerformed(ActionEvent e)
fNameInput.setText("");
miInput.setText("");
lNameInput.setText("");
productChoiceInput.setText("");
licenseQuantityInput.setText("");
streetAddressInput.setText("");
cityInput.setText("");
stateInput.setText("");
zipInput.setText("");
phoneInput.setText("");
//end clear
//end main class
【问题讨论】：
【参考方案1】：老实说，我不知道您还期望什么（无意冒犯）。
Swing 是一个事件驱动的环境。一个事件发生了，你对它做出反应……
循环将在 EDT 的上下文中开始执行，这意味着用户实际上无法关闭对话框、更正错误并尝试重新提交。
即使是这样，循环也不允许重新评估 validationError 变量的任何机会，这意味着它将始终是它最初在方法中设置的值（假设 true 为现在）...
for (int n = 1; n < 3; n++)
if (validationError)
if (n == 3)
System.exit(0);
JOptionPane.showMessageDialog(null, "Please complete each field within the order form.");
else
break;
if (validationError = false)
JOptionPane.showMessageDialog(null, "Your order has been submitted!");
System.exit(0);
所以基本上你有一个死亡陷阱，根本没有办法逃脱......
让我们采取另一种方法。我们可以创建一个软循环，而不是使用像for 或while 这样的硬循环，因此，每次执行该方法并且表单无效时，我们都会更新一个计数器，直到该计数器用完为止。 .
// How many times retries has the user used...
private int retries = 0;
/*...*/
public void actionPerformed(ActionEvent e)
validationError = (fNameInput.getText().equals("")
|| miInput.getText().equals("")
|| lNameInput.getText().equals("")
|| streetAddressInput.getText().equals("")
|| cityInput.getText().equals("")
|| stateInput.getText().equals("")
|| zipInput.getText().equals("")
|| phoneInput.getText().equals(""));
if (validationError)
retries++;
if (retries < 3)
JOptionPane.showMessageDialog(this, "Please complete each field within the order form.");
else
JOptionPane.showMessageDialog(this, "You've used up all your tries...");
System.exit(0);
else
JOptionPane.showMessageDialog(this, "Your order has been submitted!");
System.exit(0);
您可能还想阅读How to use the focus subsystem 教程中的Validating Input...
【讨论】：
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