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我想在Java中编写一个乌龟图形程序。它需要能够通过读取用户通过JTextField输入的命令来创建2D图形。我已经创建了GUI并为每个命令编写了不同的方法，例如turnRight，turnLeft，forward等。但是我遇到的问题是我在JTextField上创建了带有动作侦听器的if/else语句，以便它可以识别用户给出的命令，并尝试调用我在收到文本时写入的方法。尽管如此，该方案仍然不会画，我不确定我做错了什么。任何帮助，将不胜感激。Java乌龟图形用户输入
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
//Represents the graphics display panel within the turtle program. This panel contains an image which is updated to reflect user commands.
@SuppressWarnings("serial")
public class GraphicPanel extends JPanel
{
private int xPos = 0, yPos=0;
private boolean penUp = true;
private final static int DOWN = 0;
private final static int UP = 1;
private final static int LEFT = 2;
private final static int RIGHT = 3;
private int direction = DOWN;
GraphicPanel() {
setPreferredSize(new Dimension(800, 600));
image = new BufferedImage(700, 600, BufferedImage.TYPE_INT_RGB);
// Set max size of the panel, so that is matches the max size of the image.
setMaximumSize(new Dimension(image.getWidth(), image.getHeight()));
clear();
JTextField console = new JTextField(15);
console.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent arg0)
{
if(console.getText().contains("penup")) {
penUp();
}
else if (console.getText().contains("pendown")) {
penDown();
}
else if (console.getText().contains("turnleft")) {
JOptionPane.showMessageDialog(console, "turnleft works");
}
else if (console.getText().contains("turnright")) {
JOptionPane.showMessageDialog(console, "turnright works");
}
else if (console.getText().contains("forward")) {
forward(direction);
}
else if (console.getText().contains("backward")) {
JOptionPane.showMessageDialog(console, "backward works");
}
else if (console.getText().contains("black")) {
JOptionPane.showMessageDialog(console, "black works");
}
else if (console.getText().contains("green")) {
JOptionPane.showMessageDialog(console, "green works");
}
else if (console.getText().contains("red")) {
JOptionPane.showMessageDialog(console, "red works");
}
else if (console.getText().contains("reset")) {
JOptionPane.showMessageDialog(console, "reset works");
}
else {
JOptionPane.showMessageDialog(console, "Invalid command, try again");
}
}
});
add(console);
}
//private JTextField console = new JTextField(15);
//The default BG colour of the image.
private final static Color BACKGROUND_COL = Color.DARK_GRAY;
// The underlying image used for drawing. This is required so any previous drawing activity is persistent on the panel.
private BufferedImage image;
/*
* Draw a line on the image using the given colour.
*
* @param color
* @param x1
* @param y1
* @param x2
* @param y2
*/
// place pen onto canvas
public void penDown()
{
penUp = false;
}
//raise pen from canvas
public void penUp()
{
penUp = true;
}
// turn right from current position
public void turnRight()
{
switch(direction)
{
case UP:
direction = RIGHT;
break;
case DOWN:
direction = LEFT;
break;
case LEFT:
direction = UP;
break;
case RIGHT:
direction = DOWN;
break;
default:
break;
}
}
// turn left from current position
public void turnLeft()
{
switch(direction)
{
case UP:
direction = LEFT;
break;
case DOWN:
direction = RIGHT;
break;
case LEFT:
direction = DOWN;
break;
case RIGHT:
direction = UP;
break;
default:
break;
}
}
// draw forward a certain amount
public void forward(int amount)
{
if(penUp)
return;
if (direction == DOWN)
{
drawLine(Color.red, xPos, yPos, xPos, yPos + amount);
yPos = yPos + amount;
}
else if (direction == UP)
{
drawLine(Color.red, xPos, yPos, xPos, yPos - amount);
yPos = yPos - amount;
}
else if (direction == LEFT)
{
drawLine(Color.red, xPos, yPos, xPos - amount, yPos);
xPos = xPos - amount;
}
else if (direction == RIGHT)
{
drawLine(Color.red, xPos, yPos, xPos + amount, yPos);
xPos = xPos + amount;
}
}
// draw backwards a certain amount
public void backward(int amount)
{
if(penUp)
return;
if (direction == DOWN)
{
drawLine(Color.red, xPos, yPos, xPos, yPos - amount);
yPos = yPos - amount;
}
else if (direction == UP)
{
drawLine(Color.red, xPos, yPos, xPos, yPos + amount);
yPos = yPos + amount;
}
else if (direction == LEFT)
{
drawLine(Color.red, xPos, yPos, xPos + amount, yPos);
xPos = xPos + amount;
}
else if (direction == RIGHT)
{
drawLine(Color.red, xPos, yPos, xPos - amount, yPos);
xPos = xPos - amount;
}
}
// change colour to black
public void black()
{
Graphics g = image.getGraphics();
g.setColor(Color.black);
}
//change colour to green
public void green()
{
Graphics g = image.getGraphics();
g.setColor(Color.green);
}
// change colour to red
public void red()
{
Graphics g = image.getGraphics();
g.setColor(Color.red);
}
// draw lines to xy co-ordinates
public void drawLine(Color color, int x1, int y1, int x2, int y2) {
Graphics g = image.getGraphics();
g.setColor(color);
g.drawLine(x1, y1, x2, y2);
}
//Clears the image contents.
public void clear() {
Graphics g = image.getGraphics();
g.setColor(BACKGROUND_COL);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
}
@Override
public void paint(Graphics g) {
// render the image on the panel.
g.drawImage(image, 0, 0, null);
}
//Constructor.
}
尝试调用'重绘（）'的'JPanel'：有些东西我所做的只是为了能够运行示例代码独立。另外，重写'paintComponent'而不是'paint'。 – Berger
我试图添加重绘（），仍然没有运气 – Toby