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嘿，我有一个点类，它会生成一个点列表。该类如下没有引发异常消息
public class Point {
private double x, y;
public Point(double x, double y){
this.x = x;
this.y = y;
}//end constructor
public Point() {
// TODO Auto-generated constructor stub
}
public double getX(){
return x;
}
public void setX(double x) {
try{
if (x < 0){
throw new NegArgumentException();
}//end if
else{
this.x = x;
}//end else
}//end try
catch (NegArgumentException e){
System.out.println("error");
}//end catch
}
public double getY() {
return y;
}
public void setY(double y) {
try{
if (y < 0){
throw new NegArgumentException();
}//end if
else{
this.y = y;
}//end else
}//end try
catch (NegArgumentException e){
System.out.println("error");
}//end catch
}
public String toString(){
return "p(" + x + "," + y + ")";
}
}
我也创建了自己的异常类NegArgumentException异常如果生成负面点会引发异常。
public class NegArgumentException extends Exception {
public NegArgumentException(){}
public NegArgumentException(String message){
super(message);
}
}
我也有其他的2类矩形和圆形
public class Rectangle {
private Point upperLeft = new Point();
private Point lowerRight = new Point();
public Rectangle(Point upperLeft, Point lowerRight){
this.upperLeft = upperLeft;
this.lowerRight = lowerRight;
}//end constructor
public Point getUpperLeft() {
return upperLeft;
}
public void setUpperLeft(Point upperLeft) {
this.upperLeft = upperLeft;
}
public Point getLowerRight() {
return lowerRight;
}
public void setLowerRight(Point lowerRight) {
this.lowerRight = lowerRight;
}
public Point getUpperRight(){
return new Point(getLowerRight().getX(), getUpperLeft().getY());
}
public Point getLowerLeft(){
return new Point(getUpperLeft().getX(), getLowerRight().getY());
}
public double getArea(){
return upperLeft.getX()*lowerRight.getY();
}
public String toString(){
return "r[("+upperLeft.getX() + ","+upperLeft.getY()+"),("+lowerRight.getX()+","+lowerRight.getY()+")]";
}
}
和圆类
public class Circle {
private Point center = new Point();
private double radius;
public Circle(){}
public Circle(Point center, double radius){
this.center = center;
this.radius = radius;
}
public Point getCenter() {
return center;
}
public void setCenter(Point center) {
this.center = center;
}
public String toString(){
return "c[("+center.getX()+","+center.getY()+"), "+ radius+"]";
}
}
我的主类生成每个点的随机列表这些对象。
import java.util.ArrayList;
import java.util.Random;
公共类主要{
public static void main(String[] args) {
//create arraylist for each class
ArrayList<Point> list = new ArrayList<Point>();
ArrayList<Rectangle> list1 = new ArrayList<Rectangle>();
ArrayList<Circle> list2 = new ArrayList<Circle>();
//create random generators
Random Point = new Random();
Random myGenerator = new Random();
int i = 0;
//go through for loop
while (i < 100){
int whichArray = myGenerator.nextInt(4) + 1;
//print out points for whichever random object
if (whichArray == 1){
int pointX = Point.nextInt(41) - 20;
int pointY = Point.nextInt(41) - 20;
if (pointX >= 0 && pointY >= 0){
list.add(new Point(pointX, pointY));
System.out.println(list.toString());
list.remove(0);
i++;
}
}//end if
if (whichArray == 2){
int pointX = Point.nextInt(41) - 20;
int pointY = Point.nextInt(41) - 20;
int pointRandom = Point.nextInt(20) - 20;
if (pointX >= 0 && pointY >= 0 && pointRandom >= 0){
list1.add(new Rectangle(new Point(pointX, pointY), new Point(pointX+pointRandom, pointY-pointRandom)));
System.out.println(list1.toString());
list1.remove(0);
i++;
}
}//end if
if (whichArray == 3){
int pointX = Point.nextInt(41) - 20;
int pointY = Point.nextInt(41) - 20;
int radius = Point.nextInt(41) - 20;
if (pointX >= 0 && pointY >= 0){
list2.add(new Circle(new Point(pointX, pointY),radius));
System.out.println(list2.toString());
list2.remove(0);
i++;
}
}//end if
}//end while loop
}//end main
}//end class
的问题是，我没有看到在发生异常时显示的任何消息。我知道这是工作，因为我没有得到我的观点的负面坐标。有谁知道为什么没有消息显示？
何时和为什么会发生异常？我看到'如果（pointX> = 0 && pointY> = 0）'守卫到处！ – 2014-09-30 22:11:45
好的事情是，当我摆脱这些，任何数字，这将是消极的去0，所以我的随机坐标有更多的0比它应该@ElliottFrisch – Heyya 2014-09-30 22:13:39
为什么不只是你想开始的范围？ – 2014-09-30 22:15:10