Swing 绘制车辆时出现空白屏幕或找不到符号错误
我正在做一个项目,让汽车在屏幕上移动。我把车造出来了,但当我编辑代码以便可以多次调用该车(将其放入类中)时,它现在只会给我一个空白屏幕或“找不到符号paintComponent”错误。把它说成:Swing 绘制车辆时出现空白屏幕或找不到符号错误,swing,graphics,awt,Swing,Graphics,Awt,我正在做一个项目,让汽车在屏幕上移动。我把车造出来了,但当我编辑代码以便可以多次调用该车(将其放入类中)时,它现在只会给我一个空白屏幕或“找不到符号paintComponent”错误。把它说成: super.paintComponent(g)告诉我找不到符号 drawCar.super.paintComponent(g)告诉我找不到符号。(查看其他错误后尝试此操作) paintComponent(g)告诉我“错误:不能从静态上下文引用非静态方法paintComponent(图形)” paint
- super.paintComponent(g)告诉我找不到符号
- drawCar.super.paintComponent(g)告诉我找不到符号。(查看其他错误后尝试此操作)
- paintComponent(g)告诉我“错误:不能从静态上下文引用非静态方法paintComponent(图形)”
- paintComponent(g)编译,但给我一个空白屏幕
- 删除它会完全编译,但会给我一个空白屏幕
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.Color;
import javax.swing.*;
public class CarDriver extends JPanel
{
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame();
frame.add(new Car());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setSize(800, 800);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
仔细观察并更好地理解绘画是如何工作的
您的
paintComponent
方法是drawCar
的一种方法,但是drawCar
并不是从任何可以绘制的东西扩展而来的(比如JComponent
)
相反,您应该使drawCar
成为一个单独的类,它有一个简单的“绘制”方法,例如
public class Car {
private static final int INCREMENT = 5;
int x;
public Car(int x) {
this.x = x;
}
public void paint(Graphics g) {
// body of the car
g.setColor(Color.blue);
int xValues[] = {x + 80, x + 80, x + 180, x + 180};
int yValues[] = {60, 120, 120, 60};
Polygon polygon1 = new Polygon(xValues, yValues, 4);
g.fillPolygon(polygon1);
//hood / front end of car
int xValues2[] = {x + 180, x + 200, x + 200};
int yValues2[] = {60, 60, 90};
g.drawPolyline(xValues2, yValues2, 3);
int xValues2a[] = {x + 180, x + 180, x + 220, x + 220};
int yValues2a[] = {90, 120, 120, 90};
Polygon polygon3 = new Polygon(xValues2a, yValues2a, 4);
g.fillPolygon(polygon3);
//cartop
g.setColor(Color.black);
int xValues3[] = {x + 90, x + 90, x + 170, x + 170};
int yValues3[] = {45, 60, 60, 45};
Polygon polygon2 = new Polygon(xValues3, yValues3, 4);
g.fillPolygon(polygon2);
//wheels
g.fillOval(x + 80, 100, 35, 35);
g.fillOval(x + 180, 100, 35, 35);
}
}
public class CarPane extends JPanel {
Car car = new Car(200);
private static final int D_W = 400;
private static final int D_H = 400;
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
car.paint(g);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(D_W, D_H);
}
}
然后您可以创建一个能够实际绘制它的组件,例如
public class Car {
private static final int INCREMENT = 5;
int x;
public Car(int x) {
this.x = x;
}
public void paint(Graphics g) {
// body of the car
g.setColor(Color.blue);
int xValues[] = {x + 80, x + 80, x + 180, x + 180};
int yValues[] = {60, 120, 120, 60};
Polygon polygon1 = new Polygon(xValues, yValues, 4);
g.fillPolygon(polygon1);
//hood / front end of car
int xValues2[] = {x + 180, x + 200, x + 200};
int yValues2[] = {60, 60, 90};
g.drawPolyline(xValues2, yValues2, 3);
int xValues2a[] = {x + 180, x + 180, x + 220, x + 220};
int yValues2a[] = {90, 120, 120, 90};
Polygon polygon3 = new Polygon(xValues2a, yValues2a, 4);
g.fillPolygon(polygon3);
//cartop
g.setColor(Color.black);
int xValues3[] = {x + 90, x + 90, x + 170, x + 170};
int yValues3[] = {45, 60, 60, 45};
Polygon polygon2 = new Polygon(xValues3, yValues3, 4);
g.fillPolygon(polygon2);
//wheels
g.fillOval(x + 80, 100, 35, 35);
g.fillOval(x + 180, 100, 35, 35);
}
}
public class CarPane extends JPanel {
Car car = new Car(200);
private static final int D_W = 400;
private static final int D_H = 400;
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
car.paint(g);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(D_W, D_H);
}
}
现在,这意味着您可以拥有任意多个Car
实例,并让CarPane
绘制它们(通过将它们添加到列表中,并让CarPane
的paintComponent
方法对其进行迭代)
我强烈建议您集中精力设置汽车的基本属性,使其原点位于0x0
,然后使用Graphics2D
和AffineTransform
物理更改其喷漆位置,例如
这将大大提高性能并降低总体复杂性paintComponent
是JPanel
的受保护方法,您不能直接调用它,也不应该直接调用它。您的paintComponent
是drawCar
的方法,没有超类具有名为paintComponent
的方法,因此不能使用super.paintComponent
。向任何东西添加Car
都不会画任何东西,因为你不会“画任何东西”!这帮了大忙。在进入下一部分(使汽车在屏幕上移动)之前,我还在阅读您给我的链接。