我是JPanel的新手,并不太了解如何重置它。一旦选择了图片并且用户想要选择新图片,我希望它擦除旧的所选图片并粘贴新图片。但我不确定如何。我看过repaint()
和revalidate()
使用了,但我显然不知道如何使用它。那我该怎么做呢?
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JRadioButtonMenuItem;
public class Menu extends JFrame {
JMenuBar menuBar;
ButtonGroup pictureGroup, problemsGroup;
BufferedImage picture1img, picture2img, picture3img;
JMenu choiceOfThreePictures, numberOfProblems;
JRadioButtonMenuItem picture1, picture2, picture3, fourProblems, nineProblems, sixteenProblems;
// /Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture1.jpg
// /Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture2.png
// /Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture3.jpg
public Menu() {
// Create the menu bar.
menuBar = new JMenuBar();
setJMenuBar(menuBar);
// Create Picture choices on Menu Bar
choiceOfThreePictures = new JMenu("Picture Choices");
// Add Picture choices on Menu Bar
menuBar.add(choiceOfThreePictures);
// Create MenuItems onto Picture choices
pictureGroup = new ButtonGroup();
picture1 = new JRadioButtonMenuItem("Picture 1");
picture2 = new JRadioButtonMenuItem("Picture 2");
picture3 = new JRadioButtonMenuItem("Picture 3");
// Add Picture Choices to Picutre choices menu
choiceOfThreePictures.add(picture1);
pictureGroup.add(picture1);
choiceOfThreePictures.add(picture2);
pictureGroup.add(picture2);
choiceOfThreePictures.add(picture3);
pictureGroup.add(picture3);
// Create Number Of Problems on Menu Bar
numberOfProblems = new JMenu("Number Of Problems");
// Add Number Of problems on Menu Bar
menuBar.add(numberOfProblems);
// Create Menu Items onto Number Of problems
problemsGroup = new ButtonGroup();
fourProblems = new JRadioButtonMenuItem("4");
nineProblems = new JRadioButtonMenuItem("9");
sixteenProblems = new JRadioButtonMenuItem("16");
// Add Number Of problems onto menu
numberOfProblems.add(fourProblems);
problemsGroup.add(fourProblems);
numberOfProblems.add(nineProblems);
problemsGroup.add(nineProblems);
numberOfProblems.add(sixteenProblems);
problemsGroup.add(sixteenProblems);
// Start creating ActionListeners
picture1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.out.println("Working");
try {
picture1img = ImageIO.read(new File("/Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture1.jpg"));
getContentPane().add(new JLabel(new ImageIcon(picture1img)));
revalidate();
repaint();
setVisible(true);
} catch (IOException e) {
System.out.println("Couldn't find image.");
}
}
});
picture2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.out.println("Working");
try {
picture2img = ImageIO.read(new File("/Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture2.jpg"));
getContentPane().add(new JLabel(new ImageIcon(picture2img)));
revalidate();
repaint();
setVisible(true);
} catch (IOException e) {
System.out.println("Couldn't find image.");
}
}
});
picture3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.out.println("Working");
try {
picture3img = ImageIO.read(new File("/Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture3.jpg"));
getContentPane().add(new JLabel(new ImageIcon(picture3img)));
revalidate();
repaint();
setVisible(true);
} catch (IOException e) {
System.out.println("Couldn't find image.");
}
}
});
}
public static void main(String[] args) {
Menu mb = new Menu();
mb.setSize(900, 700);
mb.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mb.setVisible(true);
}
}
答案 0 :(得分:1)
你正在使用它很好,你甚至可以远程repaint()
调用,因为重新验证更多。问题是,您添加新图片但未从contentPane
删除以前添加的图片,这就是它不切换的原因。
所以,如果你这样做
picture3img = ImageIO.read(new File("/Users/Administrator/Dropbox/Java/HW6Wilson/HW6Wilson/Picture3.jpg"));
getContentPane().removeAll(); // HERE IS IMPORTANT PART
getContentPane().add(new JLabel(new ImageIcon(picture3img)));
revalidate();
它会起作用
更好的方法是将单个标签保持为"图像显示"并在setIcon(icon)
上使用JLabel
来保证更改整个标签。