我的作业有些问题，并希望你们可以帮助我。作业是这样的：
（ IllegalTriangleException ）编程练习11.1定义了具有三个边的三角形类。在三角形中，任何两个边的总和都大于另一边。 三角类必须遵守此规则。创建 IllegalTriangleException 类，并修改 Triangle 类的构造函数，以便在创建具有违反规则的边的三角形时抛出 IllegalTriangleException 对象，如下：
/** Construct a triangle with the specified sides */
public Triangle(double side1, double side2, double side3)
throws IllegalTriangleException {
//Implement it
}
好。这是三角类。
import java.lang.Math;
public class Triangle extends GeometricObject {
private double side1 = 1.0;
private double side2 = 1.0;
private double side3 = 1.0;
public Triangle() {
}
public Triangle(double side1, double side2, double side3) {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
}
public double getSide1() {
return side1;
}
public double getSide2() {
return side2;
}
public double getSide3() {
return side3;
}
public void setSide1(double side1) {
this.side1 = side1;
}
public void setSide2(double side2) {
this.side2 = side2;
}
public void setSide3(double side3) {
this.side3 = side3;
}
public double getArea() {
double p = getPerimeter() / 2;
return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
}
public double getPerimeter() {
return side1 + side2 + side3 ;
}
public String toString() {
return " Triangle: Side 1 = " + side1 + " Side 2 = " + side2
+ " Side 3 = " + side3;
}
}
IllegalTriangleException 类：
public class IllegalTriangleException extends Exception {
private double perimeter;
/** Construct an exception*/
public IllegalTriangleException(double perimeter) {
super( "The sum of any two sides is greater than the other side" + perimeter);
this.perimeter = perimeter;
}
/**return the side*/
public double getPerimeter() {
return perimeter;
}
}
这是 TriangleWithException 类：
public class TriangleWithException {
//The perimeter of the triangle
private double perimeter;
private double side1 = 1.0;
private double side2 = 1.0;
private double side3 = -1.0;
//Number of objects created
private static int numberOfObjects = 0;
//construct a triangle with perimeter
public TriangleWithException(double side1, double side2, double side3) {
}
//Construct a triangle with a specified perimeter.
public TriangleWithException(double newPerimeter) {
setPerimeter(newPerimeter);
numberOfObjects++;
}
//Return perimeter
public double getPerimeter() {
return perimeter;
}
//set new perimeter
public void setPerimeter(double newPerimeter) throws IllegalArgumentException {
if (newPerimeter >= 0)
perimeter = newPerimeter;
else
throw new IllegalArgumentException("Any two sides needs to be grater than the other side");
}
// Return numberOFObjects
public static int getNumberOfObjects() {
return numberOfObjects;
}
//return area of triangle
public double findArea() {
double p = getPerimeter() / 2;
return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
}
}
最后，测试程序。
public class TestTriangleWithException {
public static void main(String[] args) {
try {
new TestTriangleWithException(/** What goes here?*/);
new TestTriangleWithException(/** What goes here?*/);
new TestTriangleWithException(/** What goes here?*/);
}
catch (IllegalTriangleException ex) {
System.out.println(ex);
}
System.out.println("Number of objects created: " +
TriangleWithException.getNumberOfObjects());
}
}
class TriangleWithException {
//Perimeter
private double perimeter;
//number of objects created
private static int numberOfObjects = 0;
//Construct a triangle with a specified perimeter
public TriangleWithException() throws IllegalTriangleException {
double side1;
double side2;
double side3;
}
//construcj a triangle
public TriangleWithException(double newPerimeter)
throws IllegalTriangleException {
if (newPerimeter >= 0)
perimeter = newPerimeter;
else
throw new IllegalTriangleException(newPerimeter);
}
//Return numberofobjects
public static int getNumberOfObjects() {
return numberOfObjects;
}
//Return the area of the triangle
/** How do define getPerimeter for the type IllegalTriangleException?
* How do i resolve side1, side2 and side3 as variables?*/
public double findArea() {
double p = getPerimeter() / 2;
return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
}
}
所以，我现在面临的问题是这些：
如果违反了规则，我需要修改 Triangle 类的构造函数以抛出 IllegalTriangleException 。
我需要弄清楚Perimeter是否是我需要的变量，而不是异常类中的边。
我是初学者，所以虽然解决方案看起来很明显，但它们并不适合我。
任何帮助都将不胜感激。
答案 0 :(得分：2)
我认为应该帮助你。我将选择语句添加到构造函数中，并帮助您使用Exception类。如果您的GeometricObject课程很好，则此代码应该适合您。
import java.util.Scanner;
public class TriangleWithException {
public static void main(String[] args) throws IllegalTriangleException {
Scanner input = new Scanner(System.in);
// create triangle
Triangle triangle = new Triangle();
boolean done = false;
double side1 = 1.0;
double side2 = 1.0;
double side3 = 1.0;
System.out.println("Enter three sides: ");
while (!done) {
try {
side1 = input.nextDouble();
side2 = input.nextDouble();
side3 = input.nextDouble();
triangle = new Triangle(side1, side2, side3);
done = true;
}
catch (IllegalTriangleException ex) {
System.out.println(ex.getMessage());
System.out.print("Enter three sides: ");
input.nextLine();
}
}
System.out.println("Enter a color: ");
String color = input.next();
triangle.setColor(color);
System.out.println("Enter true or false for triangle filled: ");
boolean filled = input.nextBoolean();
triangle.setFilled(filled);
System.out.println();
System.out.println(triangle.toString() +
"\narea: " + triangle.getArea() +
"\nperimeter " + triangle.getPerimeter() +
"\ncolor: " + triangle.getColor() +
"\nfilled: " + triangle.isFilled());
}
}
原创三角课
class Triangle extends GeometricObject {
protected double side1 = 1.0;
protected double side2 = 1.0;
protected double side3 = 1.0;
public Triangle() {
}
public Triangle(double side1, double side2, double side3) throws IllegalTriangleException {
if (side1 >= side2 + side3)
throw new IllegalTriangleException(side1);
else if (side2 >= side1 + side3)
throw new IllegalTriangleException(side2);
else if (side3 >= side2 + side1)
throw new IllegalTriangleException(side3);
else {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
}
}
public double getSide1() {
return side1;
}
public double getSide2() {
return side2;
}
public double getSide3() {
return side3;
}
public double getPerimeter() {
return side1 + side2 + side3;
}
public double getArea() {
double p = (side1 + side2 + side3) / 2;
double area = Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
return area;
}
@Override
public String toString() {
return "Triangle side 1 = " + side1 + ", side 2 = " + side2 + ", side 3 = " + side3;
}
}
IllegaTriangleException类
class IllegalTriangleException extends Exception {
private double side = 1.0;
public IllegalTriangleException(double side) {
super(side + " is larger than other two combined");
}
public double getSide1() {
return side;
}
}
答案 1 :(得分：0)
从Triangle类开始：
public class Triangle extends GeometricObject {
private double side1;
private double side2;
private double side3;
public Triangle(double side1, double side2, double side3) {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
}
...
}
和例外：
public class IllegalTriangleException extends Exception {
public IllegalTriangleException() {
}
public IllegalTriangleException(String message) {
super(message);
}
...
}
现在你必须添加用于检查三角形的代码并最终抛出异常（只有结构，我不会完成整个工作）：
public class Triangle extends GeometricObject {
private double side1;
private double side2;
private double side3;
public Triangle(double side1, double side2, double side3) throws IllegalTriangleException {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
if (E*R*R*O*R)
thrown new IllegalTriangleException("Any two sides needs to be grater than the other side");
}
...
}
答案 2 :(得分：0)
在你的构造函数中，你只是在侧面，这是你应该检查Exception的时候。
所以，我们有：
side_1＆lt; side_2 + side_3
side_2＆lt; side_1 + side_3
side_3＆lt; side_1 + side_2
这可以重新安排为：
side_1＆lt; side_2 + side_3
side_1＆gt; side_2 - side_3
side_1＆gt; side_3 - side_2
这减少到：
side_1＆lt; side_2 + side_3
side_1＆gt; absolute_value（side_3 - side_2）
所以，我们有：
public TriangleWithException(double side1, double side2, double side3)
throws IllegalTriangleException {
if (side1 >= side2 + side3 || side1 <= Math.abs(side3-side2))
throw new IllegalTriangleException(yourMessage);
//otherStuffInConstructor
}