关于java：程序将识别某些键输入而不识别其他键输入。

Program will recognize certain key inputs but not others.

程序应绘制用户制作的形状。当用户按下"c"键时，应该能够在屏幕上拖动鼠标画一个圆圈。当用户按下"r"时，他们应该绘制一个矩形。当按下"l"时，应绘制一条线。当按下"o"时，应制作椭圆形。但是，由于某种原因，只能键"c"和"r"。如果没有输入使用输入，则程序应默认为圆形。然而，按"l"和"o"不会画椭圆形或线条。

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/**
* @(#)DrawShapes.java
*
*
* @author
* @version 1.00 2015/5/17
*/

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.AlphaComposite;
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.awt.geom.Ellipse2D;
import java.awt.event.KeyEvent;

import javax.swing.JComponent;
import javax.swing.JFrame;

public class DrawShapes extends JFrame implements KeyListener{

String key="";

public void keyPressed(KeyEvent event)
{
char temp = event.getKeyChar();
key = Character.toString(temp);

}

public void keyTyped (KeyEvent event) {}
public void keyReleased (KeyEvent event) {}

public DrawShapes()
{
this.setSize(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(new PaintSurface(), BorderLayout.CENTER);
this.setVisible(true);
addKeyListener(this);
}

private class PaintSurface extends JComponent
{
ArrayList<Shape> shapes = new ArrayList<Shape>();

Point startDrag, endDrag;

public PaintSurface() {

this.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e) {
startDrag = new Point(e.getX(), e.getY());
endDrag = startDrag;
repaint();
}

public void mouseReleased(MouseEvent e) {
Shape r;

if (key.equals("l"))
{
r = makeLine(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

if (key.equals("o"))
{
r = makeOval(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

if (key.equals("r"))
{
r = makeRectangle(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

else
{
r = makeCircle(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

shapes.add(r);
startDrag = null;
endDrag = null;
repaint();
}
});

this.addMouseMotionListener(new MouseMotionAdapter()
{
public void mouseDragged(MouseEvent e) {
endDrag = new Point(e.getX(), e.getY());
repaint();
}
});
}
private void paintBackground(Graphics2D g2){
g2.setPaint(Color.LIGHT_GRAY);

}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;

for (Shape s : shapes)
{
g2.setPaint(Color.BLACK);
g2.draw(s);
g2.fill(s);
}

if (startDrag != null && endDrag != null) {
g2.setPaint(Color.LIGHT_GRAY);
Shape r;

if (key.equals("l"))
{
r = makeLine(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

if (key.equals("o"))
{
r = makeOval(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

if (key.equals("r"))
{
r = makeRectangle(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

else
{
r = makeCircle(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
}

g2.draw(r);
}
}

private Rectangle2D.Float makeRectangle(int x1, int y1, int x2, int y2)
{
return new Rectangle2D.Float(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1 - x2), Math.abs(y1 - y2));
}

private Ellipse2D.Float makeCircle(int cx1, int cy1, int cx2, int cy2)
{
return new Ellipse2D.Float(Math.min(cx1, cx2), Math.min(cy1, cy2), Math.abs(cx1 - cx2), Math.abs(cx1 - cx2));
}

private Ellipse2D.Float makeOval(int ox1, int oy1, int ox2, int oy2)
{
return new Ellipse2D.Float(Math.min(ox1, ox2), Math.min(oy1, oy2), Math.abs(ox1 - ox2), Math.abs(oy1 - oy2));
}

private Line2D.Float makeLine(int lx1, int ly1, int lx2, int ly2)
{
return new Line2D.Float(Math.min(lx1, lx2), Math.min(ly1, ly2), Math.max(lx1, lx2), Math.max(ly1, ly2));
}

}

}

...

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/**
* @(#)ShapeViewer.java
*
*
* @author
* @version 1.00 2015/5/17
*/
import javax.swing.*;

public class ShapeViewer
{

//Creates and displays the application frame
public static void main(String[] args)
{
JFrame ShapeViewer = new JFrame("Draw Stuff");
ShapeViewer.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

ShapeViewer.getContentPane().add(new DrawShapes());

ShapeViewer.pack();
ShapeViewer.setVisible(true);
}

}