【发布时间】：2014-02-26 23:04:33
【问题描述】：
我为班级编写了一个程序，我相信问题是当我测试另一个班级时。
这是我粘贴的 ideone.com 的链接。
https://ideone.com/watbZq - 测试员
import static java.lang.Math.sqrt;
public class ThreePoints {
float x0;
float y0;
float x1;
float y1;
float x2;
float y2;
public ThreePoints(){
this.x0 = 0;
this.y0 = 0;
this.x1 = 0;
this.y1 = 0;
this.x2 = 0;
this.y2 = 0;
}
public ThreePoints(float x0, float y0, float x1, float y1, float x2, float y2){
this.x0 = x0;
this.y0 = y0;
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
}
public double getLength(int side){
if(side == 0 && isTriangle()){
return Math.sqrt((x2-x1) * (x2-x1) + (y2-y1) * (y2-y1));
} else if (side == 1 && isTriangle()){
return Math.sqrt((x2-x0) * (x2-x0) + (y2-y0) * (y1-y0));
} else if (side == 2 && isTriangle()){
return Math.sqrt((x1-x0) * (x1-x0) + (y1-y0) * (y1-y0));
}else{ return 0;
}
}
public double getAngle(int vertex){
if(vertex == 0 && isTriangle()) {
double angle = Math.acos((-Math.pow(this.getLength(0),2)
+Math.pow(this.getLength(1),2)
+Math.pow(this.getLength(2),2))
/(2*this.getLength(1)*this.getLength(2)));
return angle;
} else if(vertex == 1 && isTriangle()) {
double angle = Math.acos((Math.pow(this.getLength(0),2)- Math.pow(this.getLength(1),2)
+Math.pow(this.getLength(2),2))/
(2*this.getLength(0)*this.getLength(2)));
return angle;
} else if(vertex == 2 && isTriangle()){
double angle = Math.acos((Math.pow(this.getLength(0),2)
+Math.pow(this.getLength(1),2)- Math.pow(this.getLength(2),2)) /(2*this.getLength(0)*this.getLength(1)));
return angle;
} else {
return 0;
}
}
public boolean isTriangle(){
if (!(x0 * (y1-y2) + x1 * (y2-y0) + x2 * (y0-y1) == 0)){
return true;
}
return false;
}
public boolean isEquilateral(){
if (getLength(0) != getLength(1))
return false;
if (getLength(0) != getLength(2))
return false;
if (getLength(1) != getLength(2))
return false;
return true;
}
public boolean isIsosceles(){
if (getLength(0) == getLength(1))
return true;
if (getLength(0) == getLength(2))
return true;
if (getLength(1) == getLength(2))
return true;
return false;
}
public boolean isScalene(){
if (getLength(0) == getLength(1))
return true;
if (getLength(0) == getLength(2))
return true;
if (getLength(1) == getLength(2))
return true;
return false;
}
public boolean isAcute(){
if (getAngle(0) < 90 && getAngle(1) < 90 && getAngle(2) < 90){
return true;
}
return false;
}
public boolean isObtuse(){
if (getAngle(0) > 90 && getAngle(1) > 90 && getAngle(2) > 90){
return true;
}
return false;
}
public double getPerimeter(){
double perimeter;
perimeter = (getLength(0) + getLength(1) + getLength(2));
return perimeter;
}
public boolean isRight(){
if (getAngle(0) == 90 && getAngle(1) == 90 && getAngle(2) == 90){
return true;
}
return false;
}
public double getArea(){
double s = ((getLength(0) + getLength(1) + getLength(2))/2);
double area = sqrt(s * (s-getLength(0))*(s-getLength(1))*(s-getLength(2)));
return area;
}
private boolean approxEqual (double x, double y) {
return Math.abs(x - y) <= 1E-12;
}
}
这里是测试器类
public class ThreePointsTester {
public static void main(String[] args) {
ThreePoints tp = new ThreePoints();
double tpAngle0 = tp.getAngle(0);
double tpAngle1 = tp.getAngle(1);
double tpAngle2 = tp.getAngle(2);
System.out.println("tp angle 0 is " + tpAngle0);
System.out.println("tp angle 1 is " + tpAngle1);
System.out.println("tp angle 2 is " + tpAngle2);
double tpLength0 = tp.getLength(0);
double tpLength1 = tp.getLength(1);
double tpLength2 = tp.getLength(2);
System.out.println("tp side 0 is " + tpLength0);
System.out.println("tp side 1 is " + tpLength1);
System.out.println("tp side 2 is " + tpLength2);
tp.isTriangle();
tp.isEquilateral();
tp.isIsosceles();
tp.isScalene();
tp.isAcute();
tp.isObtuse();
tp.isRight();
---------------------------- ------*
ThreePoints tp2 = new ThreePoints(3.32, 2.32, 2.12, 4.54, 5.43, 4.23);
double tpAngle0 = tp2.getAngle(0);
double tpAngle1 = tp2.getAngle(1);
double tpAngle2 = tp2.getAngle(2);
System.out.println("tp2 angle 0 is " + tpAngle0);
System.out.println("tp2 angle 1 is " + tpAngle1);
System.out.println("tp2 angle 2 is " + tpAngle2);
double tpLength0 = tp2.getLength(0);
double tpLength1 = tp2.getLength(1);
double tpLength2 = tp2.getLength(2);
System.out.println("tp2 side 0 is " + tpLength0);
System.out.println("tp2 side 1 is " + tpLength1);
System.out.println("tp2 side 2 is " + tpLength2);
tp2.isTriangle();
tp2.isEquilateral();
tp2.isIsosceles();
tp2.isScalene();
tp2.isAcute();
tp2.isObtuse();
tp2.isRight();
}
}
见-------------
当我尝试创建该对象时，Java 给了我一个错误。我对Java还是很陌生，所以我只是想了解我做错了什么。另外我的布尔方法似乎没有打印真假？
【问题讨论】：
-
你遇到了什么错误？
-
方法不打印任何东西，除非它们有一个打印一些东西的语句。这些方法返回
true或false，但你只是把结果扔掉了。试试System.out.println("isTriangle = " + tp.isTriangle())或类似的东西。 -
“给我一个错误”不是错误描述。 Java 会产生一些非常好的错误消息。在此处复制消息（编辑您的原始帖子并将其粘贴），并指出该消息标识的行。
标签： java performance methods boolean vertex