我是java编程的初学者,我遇到了一个问题。我的目标是将 slider 关联起来,它为我提供图形顶点的数量,同时创建图片上的 JFieldText 坐标字段:
我的尝试导致我遇到了一个问题,我正在创建这些字段,但是尽管在 GridLayout 中采用了 2 个列,但仍有很多列,并且当我减少顶点的值时,字段却没有。这是我的代码示例:
int vertices = 3;
slider.addChangeListener(new SpinerListener());
class SpinerListener implements ChangeListener {
public void stateChanged(ChangeEvent arg0) {
vertices = slider.getValue();
right.setLayout(new GridLayout(vertices, 2));//right is my panel
for (int i = 0; i < vertices*2; i++) {
fields[i] = new JTextField("Field " + i);
right.add(fields[i]);
}
right.removeAll();
}
}
最佳答案
你可以...
使用某种List
- 它提供了动态调整大小的对象容器的概念,而不是使用数组。这样,您就可以根据 JSlider
的新值确定是否需要在 List
中添加或删除项目。
private List<JTextField[]> fields = new ArrayList<>(3);
//....
class SpinerListener implements ChangeListener {
public void stateChanged(ChangeEvent arg0) {
vertices = slider.getValue();
if (vertices < fields.size()) {
List<JTextField[]> oldFields = fields.subList(vertices + 1, fields.size());
for (JTextField[] pairs : oldFields) {
for (JTextField field : pairs) {
right.remove(field);
}
}
fields.removeAll(oldFields);
right.revalidate();
right.repaint();
} else if (vertices > fields.size()) {
int count = (vertices - fields.size());
System.out.println("Add " + count + " new fields");
for (int index = 0; index < count; index++) {
JTextField[] pairs = new JTextField[2];
pairs[0] = new JTextField(4);
pairs[1] = new JTextField(4);
for (JTextField field : pairs) {
right.add(field);
}
fields.add(pairs);
}
right.revalidate();
right.repaint();
}
}
}
所以,这是非常基本的,它只是将字段对的数量与所需的数量进行比较,并相应地增大或缩小List
。
至于GridLayout
,其实你只需要设置一次...
right = new JPanel(new GridLayout(0, 2));
来自JavaDocs
Parameters:
rows - the rows, with the value zero meaning any number of rows.
cols - the columns, with the value zero meaning any number of columns.
但是,就我个人而言,我很想使用 GridBagLayout
,但这就是我
因为我必须测试逻辑......
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JSlider slider;
private int vertices = 3;
private List<JTextField[]> fields = new ArrayList<>(3);
private JPanel right;
public TestPane() {
setLayout(new BorderLayout());
right = new JPanel(new GridLayout(0, 2));
add(new JScrollPane(right));
slider = new JSlider();
slider.addChangeListener(new SpinerListener());
slider.setValue(vertices);
add(slider, BorderLayout.NORTH);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
class SpinerListener implements ChangeListener {
public void stateChanged(ChangeEvent arg0) {
vertices = slider.getValue();
if (vertices < fields.size()) {
List<JTextField[]> oldFields = fields.subList(vertices + 1, fields.size());
for (JTextField[] pairs : oldFields) {
for (JTextField field : pairs) {
right.remove(field);
}
}
fields.removeAll(oldFields);
right.revalidate();
right.repaint();
} else if (vertices > fields.size()) {
int count = (vertices - fields.size());
System.out.println("Add " + count + " new fields");
for (int index = 0; index < count; index++) {
JTextField[] pairs = new JTextField[2];
pairs[0] = new JTextField(4);
pairs[1] = new JTextField(4);
for (JTextField field : pairs) {
right.add(field);
}
fields.add(pairs);
}
right.revalidate();
right.repaint();
}
}
}
}
}
或者你可以...
使用 JTable
,这可能更简单且更易于管理 - 请参阅 How to use tables了解更多详情
关于java - slider 监听器循环中的 JTextField,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49308159/