Rectangle 类扩展了 ClosedShape 类。当我尝试创建 Rectangle 的实例时,出现编译器错误:
类 Rectangle 中的构造函数 Rectangle 不能应用于给定类型;
我的 = 新矩形 (10, 50, 90, 50);
必需:未
找到参数:int、int、int、int
原因:实际参数列表和形式参数列表的长度不同
但是我试图调用的构造函数确实存在!为什么会这样?请参见下面的代码:
ClosedShape.java:
import java.awt.Graphics;
public abstract class ClosedShape extends Shape {
boolean polygon;
int numPoints;
int[] xVertices;
int[] yVertices;
int x, y, width, height;
public ClosedShape () {}
public ClosedShape(boolean isPolygon, int numPoints) {
super(0,0);
this.polygon = isPolygon;
this.numPoints = numPoints;
}
public ClosedShape(boolean isPolygon, int numPoints, int[] x, int[] y) {
super(x[0],y[0]);
this.polygon = isPolygon;
if (isPolygon) {
this.numPoints = numPoints;
xVertices = new int[numPoints]; // error check? if x.length == numPoints
//for (int i = 0; i < x.length; i++) { // make copy of array: why?
// xVertices[i] = x[i];
//}
yVertices = new int[numPoints]; // error check? if y.length == numPoints
for (int i = 0; i < y.length; i++) { // make copy of array
yVertices[i] = y[i];
}
}
else { // its an oval - define bounding box
this.numPoints = 4;
this.x = x[0];
this.y = y[0];
width = x[1];
height = y[1];
}
}
public void setXYCoords(int[] x, int[] y){
this.xVertices = x;
this.yVertices = y;
}
// Gives access to the width attribute
public void setWidth(int width){
this.width =width;
}
// Gives access to the height attribute
public void setHeight(int height) {
this.height =height;
}
public void draw(Graphics g) {
if (polygon) {
g.drawPolygon(xVertices, yVertices, numPoints);
}
else {
g.drawOval(x, y, width, height);
}
}
public abstract double Area();
public abstract double Perimeter();
}
矩形.java:
public class Rectangle extends ClosedShape {
public void Rectangle(int x, int y, int width, int height) {
super(true, 4);
}
public double Area() {
return 0.0;
}
public double Perimeter() {
return 0.0;
}
}
DrawingFrame.java(测试器类):
import java.awt.*;
import javax.swing.Timer;
public class DrawingFrame extends javax.swing.JPanel {
public DrawingFrame (int w, int h) {
setFocusable(true);
setBackground(Color.black);
setSize(w,h);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
//tester : Remove comments to test classes
Shape mine;
g.setColor(Color.red);
mine.draw(g);
mine = new Rectangle(10, 50, 90, 50);
g.setColor(Color.yellow);
mine.draw(g);
}
}
这里是 Shape.java,如果你需要它:
import java.awt.*;
public abstract class Shape {
int initX, initY;
Color fillColour;
public Shape() {
initX = 0;
initY = 0;
fillColour = null;
}
public Shape(int x, int y) {
initX = x;
initY = y;
}
public void setInitX (int x) {
initX = x;
}
public void setInitY (int y) {
initY = y;
}
public abstract void draw(Graphics g);
public abstract double Area();
public abstract double Perimeter();
}