Java 将JFrame容器对象居中
每次创建新的JFrame对象时,该帧都会显示在0,0位置。我曾尝试使用setLocationRelativeTo()查找如何将窗口居中,但我尝试在容器上调用的所有内容都显示为不可编译代码。下面是我正在使用的一个类:Java 将JFrame容器对象居中,java,swing,jframe,containers,centering,Java,Swing,Jframe,Containers,Centering,每次创建新的JFrame对象时,该帧都会显示在0,0位置。我曾尝试使用setLocationRelativeTo()查找如何将窗口居中,但我尝试在容器上调用的所有内容都显示为不可编译代码。下面是我正在使用的一个类: package Ginfo; import java.awt.*; import java.awt.event.*; import java.io.*; import javax.swing.*; public class EditUsers extends JFrame im
package Ginfo;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class EditUsers extends JFrame implements ActionListener
{
Container EU;
JPanel modUsers, button, output;
JLabel user, password;
JTextField tuser, tpassword;
JTextArea toutput;
JButton addAdmin, addStand, editPass, removeUser, exit;
ObjectOutputStream oout;
ObjectInputStream oin;
Message m;
ConnectInfo c;
public EditUsers (ObjectOutputStream oout2, ObjectInputStream oin2, Message m2, ConnectInfo a)
{
super("User Modifications");
EU = getContentPane();
oout = oout2;
try
{
oout.reset();
}
catch (IOException e)
{
e.printStackTrace();
}
oin = oin2;
m = m2;
c = a;
buildUserInfoPanel();
buildOutputPanel();
buildButtonPanel();
EU.add(modUsers, BorderLayout.NORTH);
EU.add(output, BorderLayout.CENTER);
EU.add(button, BorderLayout.SOUTH);
pack();
setVisible(true);
}
private void buildUserInfoPanel()
{
modUsers = new JPanel();
modUsers.setLayout(new GridLayout (2,2));
user = new JLabel ("Enter the username you wish to edit: ");
tuser = new JTextField (15);
password = new JLabel("Enter their new password: ");
tpassword = new JTextField(15);
modUsers.add(user);
modUsers.add(tuser);
modUsers.add(password);
modUsers.add(tpassword);
}
private void buildOutputPanel()
{
output = new JPanel();
toutput = new JTextArea();
toutput.setPreferredSize(new Dimension (400,100));
output.add(toutput);
}
private void buildButtonPanel()
{
button = new JPanel();
addAdmin = new JButton ("Add user as administrator");
addStand = new JButton ("Add user as standard");
editPass = new JButton ("Change password");
removeUser = new JButton ("Remove user");
exit = new JButton ("Back");
button.add(addAdmin);
button.add(addStand);
button.add(editPass);
button.add(removeUser);
button.add(exit);
addAdmin.addActionListener(this);
addStand.addActionListener(this);
editPass.addActionListener(this);
removeUser.addActionListener(this);
exit.addActionListener(this);
}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == addAdmin)
{
m.type = Message.ADDADMIN;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
m.setPermission = 1;
}
else if (e.getSource() == addStand)
{
m.type = Message.ADDSTANDARD;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
m.setPermission = 2;
}
else if (e.getSource() == editPass)
{
m.type = Message.CHANGEPASSWORD;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
}
else if (e.getSource() == removeUser)
{
m.type = Message.REMOVEUSER;
m.main = tuser.getText();
}
else if (e.getSource() == exit)
{
new WhatToDo (oout, oin, m, c);
dispose();
return;
}
try
{
oout.writeObject(m);
m = (Message)oin.readObject();
toutput.setText(m.response);
}
catch (IOException e1)
{
e1.printStackTrace();
}
catch (ClassNotFoundException e1)
{
e1.printStackTrace();
}
}
}
当我运行此代码时,窗口从(0,0)位置开始。我想做的是,将窗口的大小重新调整为运行它的计算机分辨率的1/4,并重置窗口的位置,使窗口的中心位于屏幕的中心。如果分辨率为1000x1000,则窗口应为250x250,并位于(500-250/2)X,(500-250/2)Y(左上角)乘以(500+250/2)X,(500+250/2)Y(右下角)
(请注意,我正在为每个窗口使用一个不同的类,在进程完成时打开和关闭它,因此如果没有其他类,这将无法完全编译。我正在传递我的ObjectOutputStream、ObjectInputStream、一个我调用Message的对象和另一个我调用ConnectionInfo的对象。输出和输入流将保持连接。)n对于服务器来说是活动的,消息是来回发送的序列化信息,ConnectionInfo主要保存cookie信息(已连接的用户、会话信息、权限级别等)
好的,现在我有了
package Ginfo;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class EditUsers implements ActionListener
{
Container EU;
JFrame myJFrame;
JPanel modUsers, button, output;
JLabel user, password;
JTextField tuser, tpassword;
JTextArea toutput;
JButton addAdmin, addStand, editPass, removeUser, exit;
ObjectOutputStream oout;
ObjectInputStream oin;
Message m;
ConnectInfo c;
public EditUsers (ObjectOutputStream oout2, ObjectInputStream oin2, Message m2, ConnectInfo a)
{
myJFrame = new JFrame("User Modifications");
EU = myJFrame.getContentPane();
oout = oout2;
try
{
oout.reset();
}
catch (IOException e)
{
e.printStackTrace();
}
oin = oin2;
m = m2;
c = a;
buildUserInfoPanel();
buildOutputPanel();
buildButtonPanel();
EU.add(modUsers, BorderLayout.NORTH);
EU.add(output, BorderLayout.CENTER);
EU.add(button, BorderLayout.SOUTH);
myJFrame.add(EU);
myJFrame.pack();
myJFrame.setVisible(true);
}
private void buildUserInfoPanel()
{
modUsers = new JPanel();
modUsers.setLayout(new GridLayout (2,2));
user = new JLabel ("Enter the username you wish to edit: ");
tuser = new JTextField (15);
password = new JLabel("Enter their new password: ");
tpassword = new JTextField(15);
modUsers.add(user);
modUsers.add(tuser);
modUsers.add(password);
modUsers.add(tpassword);
}
private void buildOutputPanel()
{
output = new JPanel();
toutput = new JTextArea();
toutput.setPreferredSize(new Dimension (200,100));
output.add(toutput);
}
private void buildButtonPanel()
{
button = new JPanel();
addAdmin = new JButton ("Add user as administrator");
addStand = new JButton ("Add user as standard");
editPass = new JButton ("Change password");
removeUser = new JButton ("Remove user");
exit = new JButton ("Back");
button.add(addAdmin);
button.add(addStand);
button.add(editPass);
button.add(removeUser);
button.add(exit);
addAdmin.addActionListener(this);
addStand.addActionListener(this);
editPass.addActionListener(this);
removeUser.addActionListener(this);
exit.addActionListener(this);
}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == addAdmin)
{
m.type = Message.ADDADMIN;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
m.setPermission = 1;
}
else if (e.getSource() == addStand)
{
m.type = Message.ADDSTANDARD;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
m.setPermission = 2;
}
else if (e.getSource() == editPass)
{
m.type = Message.CHANGEPASSWORD;
m.main = tuser.getText();
m.setPassword = tpassword.getText();
}
else if (e.getSource() == removeUser)
{
m.type = Message.REMOVEUSER;
m.main = tuser.getText();
}
else if (e.getSource() == exit)
{
new WhatToDo (oout, oin, m, c);
myJFrame.dispose();
return;
}
try
{
oout.writeObject(m);
m = (Message)oin.readObject();
toutput.setText(m.response);
}
catch (IOException e1)
{
e1.printStackTrace();
}
catch (ClassNotFoundException e1)
{
e1.printStackTrace();
}
}
}
现在问题出在myJFrame.add(EU)上,它说“java.lang.IllegalArgumentException:将容器的父级添加到自身”。感谢您提前提供的帮助。您必须作为GUI构造函数中的最后一行代码进行调用
JFrame#pack();
JFrame#setLocationRelativeTo(null); // Windows OS
//or JFrame#setLocationByPlatform(true); //depends of Native OS
JFrame#setVisible(true);
另一项建议
- 不要扩展JFrame,创建一个局部变量,例如
- 不要为设置首选大小
- 可能要为
设置按钮=new JPanel();
,GridLayout
默认具有JPanel
FlowLayout
EditUsers eu=new EditUsers();
放在主类中,使用JFrame
返回新的GUI实例,将代码包装到创建GUI的,希望没有其他内容:-)
编辑2
修改代码返回
源代码
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class EditUsers implements ActionListener {
private JFrame myJFrame;
private JPanel modUsers, button, output;
private JLabel user, password;
private JTextField tuser, tpassword;
private JTextArea toutput;
private JButton addAdmin, addStand, editPass, removeUser, exit;
private ObjectOutputStream oout;
private ObjectInputStream oin;
//private Message m;
//private ConnectInfo c;
public static void main(String[] a_args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
EditUsers eu = new EditUsers();
}
});
}
public EditUsers() {
//editUsers(oout2, oin2, m2, a);
buildUserInfoPanel();
buildOutputPanel();
buildButtonPanel();
myJFrame = new JFrame("User Modifications");
myJrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myJFrame.add(modUsers, BorderLayout.NORTH);
myJFrame.add(output, BorderLayout.CENTER);
myJFrame.add(button, BorderLayout.SOUTH);
myJFrame.pack();
myJFrame.setLocationRelativeTo(null);
myJFrame.setVisible(true);
}
/*private void editUsers(ObjectOutputStream oout2,
ObjectInputStream oin2, Message m2, ConnectInfo a) {
oout = oout2;
try {
oout.reset();
} catch (IOException e) {
e.printStackTrace();
}
oin = oin2;
m = m2;
c = a;
}*/
编辑3
应该在,Try
myJFrameObject.setLocationRelativeTo(null);
来自JavaDoc
- 如果组件为null,或者与此组件关联的GraphicsConfiguration为null,则窗口将位于屏幕的中心。可以使用GraphicsEnvironment.getCenterPoint方法获取中心点
- 如果该组件不为null,但当前未显示,则该窗口将位于由与该组件关联的图形配置定义的目标屏幕的中心
- 如果组件不为空且显示在屏幕上,则窗口的位置应确保窗口中心与组件中心重合
setLocationRelativeTo(null)
放在setVisible(true)
之前,以确保框架将包含所有元素,并知道居中时使用的大小
public EditUsers() {
super("User Modifications");
//I removed some not GUI operations
EU = getContentPane();
buildUserInfoPanel();
buildOutputPanel();
buildButtonPanel();
EU.add(modUsers, BorderLayout.NORTH);
EU.add(output, BorderLayout.CENTER);
EU.add(button, BorderLayout.SOUTH);
pack();
//put setLocationRelativeTo before setVisible()
setLocationRelativeTo(null);
setVisible(true);
}
在窗口的维度中或多或少初始化后,应调用
setLocationRelativeTo
关于命令后的直接示例。
pack()
命令可能会重新排列您的帧。我说我已经尝试过该命令。告诉我使用它,而不是放在哪里对我没有任何帮助。如果我只是将按钮放在窗格底部,制作按钮GridLayout(1,5)会做什么(除了能够在按钮之间留出空间外)?例如,刚刚更新了我的示例以不扩展JFrame,但是我想我对内容窗格如何工作的理解是不正确的。当我尝试将内容窗格添加到新的JFrame对象(myJFrame)时,我收到一个父级添加自身错误。我不需要添加myJFrame.add(EU)?如果是这种情况,那么是JFrame对象还是myJFrame?我不知道在EditUsers实例中生成一个新的EditUsers()对任何事情都有帮助。您的这一行是错误的myJFrame=new JFrame(“用户修改”);
,您不应该重新初始化它,更好的是,如果您没有以任何方式增强类的行为或功能,就不要继承该类。尽管快速的补救方法是删除这一行,只需为其他组件编写getContentPane().add(modUsers,BorderLayout.NORTH);等等thenpack();setLocationRelativeTo(null);setVisible(true);
。当您编写frame.add(component)
时,实际上是在JFrame
的中心向其内容窗格添加一个组件
给您一个错误,因为EU是所讨论的JFrame
的ContentPane
,您在编写EU=myJFrame.getContentPane()时得到了它
在这里尝试一下,这扩展了JFrame
,可能会给你一个想法,如何去做。这里还有一个解决方法谢谢你非常欢迎,保持微笑:-)
public EditUsers() {
super("User Modifications");
//I removed some not GUI operations
EU = getContentPane();
buildUserInfoPanel();
buildOutputPanel();
buildButtonPanel();
EU.add(modUsers, BorderLayout.NORTH);
EU.add(output, BorderLayout.CENTER);
EU.add(button, BorderLayout.SOUTH);
pack();
//put setLocationRelativeTo before setVisible()
setLocationRelativeTo(null);
setVisible(true);
}