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我如何从另一个类访问输入的值“用户名”?包装内我在编码时遇到问题。我应该公开一些变量吗?我公开了用户名,但出现错误
这是我的代码:
package login;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.JOptionPane;
@SuppressWarnings("serial")
public class Login extends javax.swing.JFrame {
public Login() {
initComponents0();
}
@SuppressWarnings("unchecked")
private void initComponents0() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
uname = new javax.swing.JTextField();
jLabel3 = new javax.swing.JLabel();
login = new javax.swing.JButton();
reset = new javax.swing.JButton();
pwd = new javax.swing.JPasswordField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
jLabel1.setText("Login Pane");
jLabel2.setText("User Name:");
jLabel3.setText("Password:");
login.setText("Login");
login.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String un = uname.getText();
@SuppressWarnings("deprecation")
String pw = pwd.getText();
try{
FileInputStream fstream = new FileInputStream("data.dat");
try (DataInputStream in = new DataInputStream(fstream)) {
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
boolean registered = false;
boolean registered0 = false;
while ((strLine = br.readLine()) != null) {
String values[] = strLine.split("\\|");
if ((strLine.startsWith(un))&&(pw.equals(values[1]))){
registered = true;
break;
}
if ((strLine.startsWith(un))&&(!pw.equals(values[1]))){
registered0 = true;
break;
}
}
if(registered){
JOptionPane.showMessageDialog(null,"Hello: "+un ,"Registration",JOptionPane.INFORMATION_MESSAGE);
File file = new File("temp.dat");
try {
try (FileWriter writer = new FileWriter(file, false)) {
String data0 = un;
writer.write(data0);
}}
catch (IOException | HeadlessException z) {
JOptionPane.showMessageDialog(null, e);
}
}
else if(registered0){JOptionPane.showMessageDialog(null,"It seems you entered a wrong password! \n Please try again " ,"Admin",JOptionPane.INFORMATION_MESSAGE);}
else
{
int sel = JOptionPane.showConfirmDialog(null,"It seems that you haven't registered yet? \n Launch Registration Pane?","Admin",JOptionPane.INFORMATION_MESSAGE);
if (sel == JOptionPane.YES_OPTION){
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Register().setVisible(true);
}});}
}}}
catch ( IOException | HeadlessException ez){
JOptionPane.showMessageDialog(null,"A null file was created in order to \n avoid File Catch errors","Admin",JOptionPane.INFORMATION_MESSAGE);
File file = new File("data.dat");
try {
try (FileWriter writer = new FileWriter(file, true)) {
String data0 = "null";
String data1 = "null";
writer.write(data0+" | "+data1+"\n");
}}
catch (IOException | HeadlessException z) {
JOptionPane.showMessageDialog(null, e);
}
}
}});
reset.setText("Reset Field");
reset.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
uname.setText("");
pwd.setText("");
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel1)
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, 300, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(login, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(reset, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(pwd))))
.addContainerGap(30, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(pwd, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(login)
.addComponent(reset))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Login().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JButton login;
private javax.swing.JPasswordField pwd;
private javax.swing.JButton reset;
private javax.swing.JTextField uname;
// End of variables declaration
}
已编辑
package login;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.JOptionPane;
@SuppressWarnings("serial")
public class Login extends javax.swing.JFrame {
private String username,password;
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
public Login() {
initComponents0();
}
@SuppressWarnings("unchecked")
private void initComponents0() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
uname = new javax.swing.JTextField();
jLabel3 = new javax.swing.JLabel();
login = new javax.swing.JButton();
reset = new javax.swing.JButton();
pwd = new javax.swing.JPasswordField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
jLabel1.setText("Login Pane");
jLabel2.setText("User Name:");
jLabel3.setText("Password:");
login.setText("Login");
login.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String un = uname.getText();
@SuppressWarnings("deprecation")
String pw = pwd.getText();
username = un;
password = pw;
try{
FileInputStream fstream = new FileInputStream("data.dat");
try (DataInputStream in = new DataInputStream(fstream)) {
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
boolean registered = false;
boolean registered0 = false;
while ((strLine = br.readLine()) != null) {
String values[] = strLine.split("\\|");
if ((strLine.startsWith(un))&&(pw.equals(values[1]))){
registered = true;
break;
}
if ((strLine.startsWith(un))&&(!pw.equals(values[1]))){
registered0 = true;
break;
}
}
if(registered){
username = un;
password = pw;
JOptionPane.showMessageDialog(null,"Hello: "+un ,"Registration",JOptionPane.INFORMATION_MESSAGE);
File file = new File("temp.dat");
try {
try (FileWriter writer = new FileWriter(file, false)) {
String data0 = un;
writer.write(data0);
}}
catch (IOException | HeadlessException z) {
JOptionPane.showMessageDialog(null, e);
}
}
else if(registered0){JOptionPane.showMessageDialog(null,"It seems you entered a wrong password! \n Please try again " ,"Admin",JOptionPane.INFORMATION_MESSAGE);}
else
{
int sel = JOptionPane.showConfirmDialog(null,"It seems that you haven't registered yet? \n Launch Registration Pane?","Admin",JOptionPane.INFORMATION_MESSAGE);
if (sel == JOptionPane.YES_OPTION){
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Register().setVisible(true);
}});}
}}}
catch ( IOException | HeadlessException ez){
JOptionPane.showMessageDialog(null,"A null file was created in order to \n avoid File Catch errors","Admin",JOptionPane.INFORMATION_MESSAGE);
File file = new File("data.dat");
try {
try (FileWriter writer = new FileWriter(file, true)) {
String data0 = "null";
String data1 = "null";
writer.write(data0+" | "+data1+"\n");
}}
catch (IOException | HeadlessException z) {
JOptionPane.showMessageDialog(null, e);
}
}
}});
reset.setText("Reset Field");
reset.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
uname.setText("");
pwd.setText("");
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel1)
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, 300, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(login, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(reset, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(pwd))))
.addContainerGap(30, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(pwd, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(login)
.addComponent(reset))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}
/*
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Login().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JButton login;
private javax.swing.JPasswordField pwd;
private javax.swing.JButton reset;
private javax.swing.JTextField uname;
// End of variables declaration
}
最佳答案
制作private
全局非静态字段来保存username
和password
字段,当您接受输入时将值分配给您的全局username
和 password
变量。然后有 public
的 getter 方法,并返回该实例的 username
和 password
。
类似于:
public class Login extends javax.swing.JFrame {
private String username,password;//assign private global fields for the instance
//the variables are assigned when you accept user input
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
}
然后你会做类似的事情:
Login lg=new Login();//create new instance to gain access to getter methods
//wait for it to return or until user has enetered the credentials
System.out.println(lg.getUsername());
System.out.println(lg.getPassword());
关于java - 如何从类中访问字符串,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12141542/
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