Question

求一个简单的java代码：（图形界面）

一个JTextArea，要求定义个字符串，运行后在JTextArea中显示出来即可。（简单点不要用匿名对象）

Answer 1

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class vv extends JDialog {

private static final long serialVersionUID = 1L;

private JLabel l_Id = new JLabel("登陆账户", JLabel.CENTER);
private JLabel l_pw = new JLabel("登陆密码", JLabel.CENTER);
private JTextField t_Id = new JTextField(10);
private JPasswordField t_pw = new JPasswordField(10);
private JButton btnLogin;
private JButton btnClose;

public vv() {
super();
setResizable(false);
getContentPane().setBackground(new Color(225, 225, 225));
getContentPane().setLayout(null);
initialize();
}

protected void initialize() {
setTitle("系统登录");

l_Id.setBounds(48, 43, 53, 25);
t_Id.setBounds(110, 43, 150, 25);
l_pw.setBounds(48, 93, 53, 25);
t_pw.setBounds(110, 93, 150, 25);

getContentPane().add(l_Id);
getContentPane().add(l_pw);
getContentPane().add(t_Id);
getContentPane().add(t_pw);

btnLogin = new JButton();

btnLogin.setText("登 录");
btnLogin.setBounds(70, 142, 85, 28);
btnLogin.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
addBtnLoginActionListener();
}
});

getContentPane().add(btnLogin);

btnClose = new JButton();

btnClose.setText("关 闭");
btnClose.setBounds(175, 142, 85, 28);
btnClose.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
dispose();
System.exit(-1);
}
});
getContentPane().add(btnClose);
}

private void addBtnLoginActionListener() {
String user = t_Id.getText();
String password = new String(t_pw.getPassword());

if (user.equals("")) {
JOptionPane.showMessageDialog(this, "帐号不可为空", "Caution",
JOptionPane.WARNING_MESSAGE);
return;
}

if (password.equals("")) {
JOptionPane.showMessageDialog(this, "密码不可为空", "Caution",
JOptionPane.WARNING_MESSAGE);
return;
}

String sql = "select * FROM login WHERE id = '" + user + "' and pw = '"
+ password + "'";

boolean success = false;

// TODO:数据校验 success = executeQuery(sql);

if (success) {
// TODO： 如果数据校验成功 显示主界面 并关闭登录界面

JOptionPane.showMessageDialog(this, "成功登录", "提示",
JOptionPane.INFORMATION_MESSAGE);
this.dispose();
} else {
JOptionPane.showMessageDialog(this, "帐号或密码错误!", "警告",
JOptionPane.WARNING_MESSAGE);
t_pw.requestFocus(); // 密码框选中
}

}

public Dimension getPreferredSize() {
return new Dimension(320, 170);
}

public void show() {
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension screen = tk.getScreenSize();
Dimension d = getSize();
this.setLocation((screen.width - d.width) / 2,
(screen.height - d.height) / 2);

// 输入密码后回车相当于点击了登录按钮
getRootPane().setDefaultButton(btnLogin);
t_pw.requestFocus();
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setSize(300, 220);
super.show();
}

public static void main(String[] args) {
vv loginFrame = new vv();
loginFrame.setVisible(true);
}
}
希望对你有帮助

Answer 2

直接写main函数里了
public static void main(String[] args) {

JFrame ck = new JFrame("title");
JPanel mb = new JPanel();
mb.setLayout(null);
String str = "test"; //自己定义要显示什么
JTextArea ta = new JTextArea(str);
ta.setBounds(0, 0, 100, 30); //自己定义文本区在窗口中的位置和大小
mb.add(ta);
ck.add(mb);
ck.setVisible(true);
ck.setBounds(200, 200, 500, 500); //自己定义窗口位置和大小

}

追问

显示不出来啊

追答

......新建个类,直接把这段粘进去,在类窗口上右键--运行方式--Java 应用程序

Answer 3

import javax.swing.JFrame;
import javax.swing.JTextArea;

public class Test extends JFrame {
public Test() {
String str = "abc";
JTextArea jTextArea = new JTextArea(str);
this.add(jTextArea);
}

public static void main(String args[]) {
Test t = new Test();
t.setSize(200, 200);
t.setVisible(true);
t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}