我制作了一个计算器，一旦我得到答案，我希望标签 l4 在屏幕上连续移动。任何人都可以告诉我如何让它移动，因为我无法弄清楚。
import java.awt.*;
import java.awt.event.*;
import java.awt.Label;
import java.awt.Font;
import javax.swing.*;
class DanielCalculator implements ActionListener {
Timer t = new Timer(5, this);
int x = 300;
int y = 50;
DanielCalculatorFrame f = new DanielCalculatorFrame();
Label l1 = new Label("First Number");
Label l2 = new Label("Second Number");
Label l3 = new Label("Result: ");
TextField t1 = new TextField();
TextField t2 = new TextField();
Label l4 = new Label("0");
Button b1 = new Button("Add");
Button b2 = new Button("Subtract");
Button b3 = new Button("Multiply");
Button b4 = new Button("Divide");
DanielCalculator()
{
l1.setBounds(20, 70, 100, 20);
l2.setBounds(240, 70, 100, 20);
l3.setBounds(70, 168, 100, 50);
t1.setBounds(120, 70, 100, 20);
t2.setBounds(360, 70, 100, 20);
b1.setBounds(230, 130, 50, 20); //3
b2.setBounds(330, 130, 50, 20); //4
b3.setBounds(30, 130, 50, 20); //1
b4.setBounds(130, 130, 50, 20); //2
f.add(l1);
f.add(l2);
f.add(l3);
f.add(t1);
f.add(t2);
f.add(l4);
f.add(b1);
f.add(b2);
f.add(b3);
f.add(b4);
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);
f.setLayout(null);
f.setVisible(true);
f.setSize(600,450);
Font myFont = new Font("Serif",Font.BOLD,26);
l4.setFont(myFont);
l3.setFont(myFont);
l4.setBounds(200, 170, x, y);
}
public void actionPerformed(ActionEvent e)
{
double continuee;
Double n1=Double.parseDouble(t1.getText());
Double n2=Double.parseDouble(t2.getText());
if(e.getSource() == b1) {
l4.setText(String.valueOf(n1+n2));\
}
if(e.getSource() == b2) {
l4.setText(String.valueOf(n1-n2));
}
if(e.getSource() == b3) {
l4.setText(String.valueOf(n1*n2));
}
if(e.getSource() == b4) {
l4.setText(String.valueOf(n1/n2));
}
}
public static void main (String[] args) {
new DanielCalculator();
}
}
最佳答案
可能最简单的解决方案是使用框架的玻璃面板，因为它允许您独立于主视图控制布局。
说到布局......这就是为什么你应该避免 null 布局......
此示例使用框架的玻璃 Pane 功能来提供将显示在主 UI 上方的动画层
ResultsPane 确实使用了 null 布局，这是您可以提供此类功能的唯一方式，但它所做的是确保它尊重组件的首选大小，允许字体、字体规范和其他可能影响其他平台大小的渲染差异...
基本计算面板使用复合布局方法，其中字段和按钮彼此独立布局。
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import javax.swing.AbstractAction;
import static javax.swing.Action.NAME;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestCalculator {
public static void main(String[] args) {
new TestCalculator();
}
public TestCalculator() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
ResultPane resultPane = new ResultPane();
JFrame frame = new JFrame("Testing");
frame.setGlassPane(resultPane);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new CalculatorPane(resultPane));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ResultPane extends JPanel {
private JLabel result;
private Timer timer;
private int xDelta = (Math.random() > 0.5) ? 1 : -1;
private int yDelta = (Math.random() > 0.5) ? 1 : -1;
;
public ResultPane() {
setOpaque(false);
setLayout(null);
result = new JLabel();
Font font = result.getFont();
font = font.deriveFont(Font.BOLD, 26f);
result.setFont(font);
add(result);
timer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
Point point = result.getLocation();
point.x += xDelta;
point.y += yDelta;
if (point.x < 0) {
point.x = 0;
xDelta *= -1;
} else if (point.x + result.getWidth() > getWidth()) {
point.x = getWidth() - result.getWidth();
xDelta *= -1;
}
if (point.y < 0) {
point.y = 0;
yDelta *= -1;
} else if (point.y + result.getHeight() > getHeight()) {
point.y = getHeight() - result.getHeight();
yDelta *= -1;
}
result.setLocation(point);
repaint();
}
});
timer.start();
}
public void setResult(Number number) {
result.setText("Result: " + NumberFormat.getNumberInstance().format(number));
result.setSize(result.getPreferredSize());
setVisible(true);
}
}
public class CalculatorPane extends JPanel {
private final ResultPane resultPane;
private final JLabel firstNumberLabel = new JLabel("First Number:");
private final JLabel secondNumberLabel = new JLabel("Second Number:");
private final JTextField firstNumberField = new JTextField(5);
private final JTextField secondNumberField = new JTextField(5);
public CalculatorPane(ResultPane resultPane) {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
this.resultPane = resultPane;
JPanel fields = new JPanel();
fields.add(firstNumberLabel);
fields.add(firstNumberField);
fields.add(secondNumberLabel);
fields.add(secondNumberField);
add(fields, gbc);
JPanel buttons = new JPanel();
buttons.add(new JButton(new AddAction()));
buttons.add(new JButton(new SubtractAction()));
buttons.add(new JButton(new MultiplyAction()));
buttons.add(new JButton(new DivideAction()));
add(buttons, gbc);
}
public class AddAction extends AbstractAction {
public AddAction() {
putValue(NAME, "+");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 + num2;
resultPane.setResult(result);
} catch (NumberFormatException exp) {
}
}
}
public class SubtractAction extends AbstractAction {
public SubtractAction() {
putValue(NAME, "-");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 - num2;
resultPane.setResult(result);
} catch (NumberFormatException exp) {
}
}
}
public class MultiplyAction extends AbstractAction {
public MultiplyAction() {
putValue(NAME, "x");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 * num2;
resultPane.setResult(result);
} catch (NumberFormatException exp) {
}
}
}
public class DivideAction extends AbstractAction {
public DivideAction() {
putValue(NAME, "/");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 / num2;
resultPane.setResult(result);
} catch (NumberFormatException exp) {
}
}
}
}
}
看看How to Use Root Panes了解更多详情
不要使用null 布局。像素完美布局是现代 UI 设计中的一种错觉，您无法控制字体、DPI、渲染管道或其他会改变组件在屏幕上呈现方式的因素。
Swing 旨在与布局管理器一起克服这些问题。如果您坚持忽略这些功能并反对 API 设计，请准备好面对很多令人头疼的事情和永无休止的艰苦工作......
关于Java 使标签移动？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23689880/