java框架不会为空并使用if语句重新绘制
我有一个if语句来检查是真是假，enterGame，它会将内容添加到JFrame，有一个按钮会将布尔值更改为true，并在JFrame清空后尝试替换其中的内容。一旦我把所有的东西都移走，它就不会重新粉刷我的画框。克里斯托是我的老师，我们都被难倒了
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import javax.swing.*;
public class GUIDemo implements ActionListener
{
int mapX, mapY;
private JFrame mainFrame;
private JLabel headerLabel;
private JLabel statusLabel;
private JPanel controlPanel;
private JPanel mainPanel = new JPanel();
private JPanel logonPanel = new JPanel();
private JLabel msglabel;
private JButton logButton;
boolean enterGame = false;
JLabel userLabel = new JLabel("Username:", JLabel.CENTER);
JLabel passLabel = new JLabel("Password:", JLabel.CENTER);
JLabel[][] maplabels = new JLabel[3][3];
public String[][] placeNames = { {"Forest", "Desert", "Jungle"},
{"Ice Cave", "Village", "Wizard's Tower"},
{"Lake", "Moutain", "Ocean"}};
public GUIDemo()
{
prepareGUI();
}
public static void main(String[] args)
{
GUIDemo swingDemo = new GUIDemo();
swingDemo.showDemo();
}
private void prepareGUI()
{
mainFrame = new JFrame("Swing Demo");
mainFrame.setSize(350,200);
mainFrame.setLayout(new BorderLayout());
mainPanel.setLayout(new BorderLayout());
logonPanel.setLayout(new GridLayout(3, 1));
//mainFrame.setLayout(null);
headerLabel = new JLabel("",JLabel.CENTER );
statusLabel = new JLabel("",JLabel.CENTER);
mainFrame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent windowEvent)
{
System.exit(0);
}
});
controlPanel = new JPanel();
controlPanel.setLayout(new FlowLayout());
mainFrame.add(logonPanel, BorderLayout.CENTER);
//mainFrame.add(mainPanel, BorderLayout.CENTER);
//mainFrame.add(statusLabel);
mainPanel.setVisible(false);
logonPanel.setVisible(true);
mainFrame.setVisible(true);
}
private void showDemo()
{
if (enterGame == true)
{
//logonPanel.setVisible(false);
//mainFrame.setVisible(false);
mainFrame.remove(logonPanel);
mainFrame.validate();
mainFrame.repaint();
//mainFrame.removeAll();
headerLabel.setText("Location: " + placeNames[mapX][mapY]);
JPanel panel = new JPanel();
JPanel panel2 = new JPanel();
panel.setSize(300,300);
panel2.setSize(300,300);
GridLayout compassLayout = new GridLayout(3,3);
JButton button1 = new JButton("");
JButton button2 = new JButton("North");
JButton button3 = new JButton("");
JButton button4 = new JButton("West");
JButton button5 = new JButton("");
JButton button6 = new JButton("East");
JButton button7 = new JButton("");
JButton button8 = new JButton("South");
JButton button9 = new JButton("");
button1.setVisible (false);
button2.addActionListener(this);
button3.setVisible (false);
button4.addActionListener(this);
button5.setVisible (false);
button6.addActionListener(this);
button7.setVisible (false);
button8.addActionListener(this);
button9.setVisible (false);
GridLayout MapLayout = new GridLayout(3,3);
maplabels[0][0] = new JLabel("F", JLabel.CENTER);
maplabels[0][1] = new JLabel("D", JLabel.CENTER);
maplabels[0][2] = new JLabel("J", JLabel.CENTER);
maplabels[1][0] = new JLabel("I", JLabel.CENTER);
maplabels[1][1] = new JLabel("V", JLabel.CENTER);
maplabels[1][2] = new JLabel("W", JLabel.CENTER);
maplabels[2][0] = new JLabel("L", JLabel.CENTER);
maplabels[2][1] = new JLabel("M", JLabel.CENTER);
maplabels[2][2] = new JLabel("O", JLabel.CENTER);
panel.setBorder(BorderFactory.createLineBorder(Color.black));
panel.setLayout(compassLayout);
panel.add(button1);
panel.add(button2);
panel.add(button3);
panel.add(button4);
panel.add(button5);
panel.add(button6);
panel.add(button7);
panel.add(button8);
panel.add(button9);
panel2.setBorder(BorderFactory.createLineBorder(Color.black));
panel2.setLayout(MapLayout);
panel2.add(maplabels[0][0]);
panel2.add(maplabels[0][1]);
panel2.add(maplabels[0][2]);
panel2.add(maplabels[1][0]);
panel2.add(maplabels[1][1]);
panel2.add(maplabels[1][2]);
panel2.add(maplabels[2][0]);
panel2.add(maplabels[2][1]);
panel2.add(maplabels[2][2]);
mainPanel.add(headerLabel, BorderLayout.PAGE_START);
mainPanel.add(panel, BorderLayout.LINE_START);
mainPanel.add(panel2, BorderLayout.CENTER);
mainFrame.add(mainPanel, BorderLayout.CENTER);
}
else
{
//mainFrame.removeAll();
BorderLayout borderUser = new BorderLayout();
BorderLayout borderPass = new BorderLayout();
JPanel userPanel = new JPanel(borderUser);
JPanel passPanel = new JPanel(borderPass);
logButton = new JButton("Log On");
logButton.addActionListener(this);
JTextField userField = new JTextField();
JTextField passField = new JTextField();
userPanel.add(userLabel, BorderLayout.CENTER);
userPanel.add(userField, BorderLayout.PAGE_END);
passPanel.add(passLabel, BorderLayout.CENTER);
passPanel.add(passField, BorderLayout.PAGE_END);
logonPanel.add(userPanel);
logonPanel.add(passPanel);
logonPanel.add(new JPanel());
logonPanel.add(logButton);
}
mainFrame.validate();
mainFrame.repaint();
mainFrame.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
String buttonName = ((JButton) e.getSource()).getText();
//userLabel.setText(buttonName);
if(buttonName == "Log On")
{
//userLabel.setText("HI");
enterGame = true;
this.showDemo();
}
else
{
maplabels[mapX][mapY].setBorder(BorderFactory.createEmptyBorder());
if(buttonName == "North")
{
mapX = (3 + mapX - 1)% 3;
}
if(buttonName == "South")
{
mapX = (3 + mapX + 1)% 3;
}
if(buttonName == "West")
{
mapY = (3 + mapY - 1)% 3;
}
if(buttonName == "East")
{
mapY = (3 + mapY + 1)% 3;
}
maplabels[mapX][mapY].setBorder(BorderFactory.createLineBorder(Color.blue));
headerLabel.setText("Location: " + placeNames[mapX][mapY]);
}
}
}
# 1 楼答案
代码中有两个错误。首先，将字符串与双等号进行比较，即（==）。这永远不会完成你的工作。在java中，如果要比较的对象不是基元类型（哪个字符串不是基元类型），那么它将进行引用比较。因此，你的比较按钮name==某些东西永远不会返回真值
其次，登录后会出现一个空白窗口，因为尚未将主面板的可见性设置为true。下面是正确的代码：