我的第一篇文章。我是第一年获得理科学位的学生。
我只是为一个赋值构建了一个基本的GUI，由于某些原因，我在我的生活中看不到，我创建的一个JFrame，Register Class的一个实例在从它调用时显示为完全空白登录类中的注册按钮动作侦听器...
我还有一个单独的主类，它包含Main方法并调用Login类。登录类JFrame工作正常，如上所述，只有在登录类的“注册”按钮动作侦听器中调用注册类时才会出现问题。程序中的所有其他JFrame也可以正常工作。
我试图直接从main调用Register Class，它有同样的问题，虽然我试图将它缩减为最基本的形式，除了空白的未着色的JFrame之外它仍然没有显示任何内容。
这是代码（未完成但按原样工作）。我为我的草率道歉，但我是一个完全的初学者。
有人能看出它有什么问题吗？
提前致谢！
package guitest;
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class Register extends JFrame{
JButton regSubmit = new JButton("Submit");
JTextField email = new JTextField();
JTextField name = new JTextField();
JTextField Address1 = new JTextField();
JTextField Address2 = new JTextField();
JPasswordField password1 = new JPasswordField();
JPasswordField password2 = new JPasswordField();
String nameTxt = email.getText();
String passTxt = password1.getText();
String info = "";
FlowLayout layout1 = new FlowLayout();
public void Reg(){
this.setTitle("La Volpe Registration");
this.setLayout(layout1);
this.add(Address1);
this.add(Address2);
this.add(email);
this.add(password1);
this.add(password2);
this.add(name);
this.add(regSubmit);
this.getContentPane().setBackground(Color.green);
this.setSize(370, 160);
regSubmit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
regSubmitActionPerformed(evt);
}
private void regSubmitActionPerformed(java.awt.event.ActionEvent evt) {
String name = email.getText();
String pass = password1.getText();
String info = "";
System.out.println("registering...");
boolean eof;
try{
// Create file
FileWriter file = new FileWriter("\\regdata.txt");
BufferedWriter out = new BufferedWriter(file);
out.write("\n"+nameTxt+", "+passTxt);
}
catch (Exception e){
}
}
});
this.setVisible(true);
}
}
与之相关的课程......
package guitest;
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
/**
* @author david
*/
public class Login {
JFrame loginFrame = new JFrame();
Register reg3 = new Register();
JButton submit = new JButton("Submit");
JButton clear = new JButton("Clear");
JButton register = new JButton ("Register with Us");
JPasswordField pass = new JPasswordField(20);
JTextField email = new JTextField(20);
JLabel em = new JLabel("Email Address: ");
JLabel pw = new JLabel("Password: ");
String pathname;
String line;
String [] records = new String [1000];
int count = 0;
FlowLayout layout1 = new FlowLayout();
public Login(){
//Adds Email label and text field
loginFrame.add(em);
loginFrame.add(email);
//Adds password label and field
loginFrame.add(pw);
loginFrame.add(pass);
//Adds buttons
loginFrame.add(submit);
loginFrame.add(clear);
loginFrame.add(register);
loginFrame.getContentPane().setBackground(Color.green);
loginFrame.setLayout(layout1);
loginFrame.setSize(370, 160);
loginFrame.setTitle("La Volpe - Login");
submit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
submitActionPerformed(evt);
}
private void submitActionPerformed(java.awt.event.ActionEvent evt){
String emailadd = email.getText();
String password = pass.getText();
pathname = "\\regdata.txt";
boolean eof;
try{
FileReader file = new FileReader(pathname);
BufferedReader buff = new BufferedReader(file);
eof = false; // set the eof boolean to false
while (!eof){
line = buff.readLine();
if (line == null){ // test to see if the end of file has been reached
eof = true; // if the end of file has been found set the eof Boolean to true
}
else{
// end of file not reached so move the contents of the line to the records
//array
records[count] = line;
count ++;
System.out.println(line); // print out the new line input for error checking
}
}
buff.close();
}
catch (IOException e){
System.out.println("Error -- "+ e.toString());
}
boolean notTrue = false;
for (int i = 0; i < count; i++) {
if ((!notTrue)&&((emailadd + "," + password).equals(records[i]))) {
FoodSelectionMain loggedIn = new FoodSelectionMain();
loggedIn.setVisible(true);
}
}
if (!notTrue){
JOptionPane.showInputDialog("Please check your login "
+ "and try again. If you are a new user, please "
+ "register by pressing the 'REGISTER' button");
}
}
});
// TODO add your handling code here:
clear.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
clearActionPerformed(evt);
}
public void clearActionPerformed(java.awt.event.ActionEvent evt){
email.setText(null);
pass.setText(null);
}
});
register.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
registerActionPerformed(evt);
}
public void registerActionPerformed(java.awt.event.ActionEvent evt){
reg3.setVisible(true);
System.out.println("Register pressed");
}
});
loginFrame.setVisible(true);
}
}
答案 0 :(得分：1)
试试这个， 在Register类中，将构造函数名称从Reg（）更正为Register（）。
在构建gui app之前，请记住这些指南
创建容器子类的对象。
将容器中的所有组件视为实例变量。
在方法中的构造函数外部设置这些实例变量和事件处理（即setComponent（），setHandler（）等），但是从构造函数执行这些方法调用。
现在主要使用这个......
EventQueue.invokeLater(new Runnable() {
public void run() {
Myframe f = new Myframe();
f.setVisible(true);
}
}