【大数据】学习笔记 1 Java SE 第8章异常 8.3 自定义异常

迷南。 2024-03-22 11:44 39阅读 0赞

### 【大数据】学习笔记 ###

#### 文章目录 ####

*   *  【大数据】学习笔记
     *   *  1 Java SE
         *   *  第8章 异常
             *   *  8.3 自定义异常

![在这里插入图片描述][c4411eace5c4445da8ac4dc8eea41dfa.png_pic_center]

#### 1 Java SE ####

##### 第8章 异常 #####

###### 8.3 自定义异常 ######

**为什么需要自定义异常类:**

我们说了Java中不同的异常类,分别表示着某一种具体的异常情况,那么在开发中总是有些异常情况是核心类库中没有定义好的，此时我们需要根据自己业务的异常情况来定义异常类。例如年龄负数问题，考试成绩负数问题等等。

**异常类如何定义:**

1.  自定义一个编译时异常类型：自定义类 并继承`java.lang.Exception`。
2.  自定义一个运行时异常类型：自定义类 并继承`java.lang.RuntimeException`。

注意自定义的异常只能通过throw抛出。

**演示自定义异常：**

package com.dingjiaxiong.define;
    
    /**
     * @Projectname: BigDataStudy
     * @Classname: NotTriangleException
     * @Author: Ding Jiaxiong
     * @Date:2023/4/27 15:17
     */
    
    public class NotTriangleException extends Exception {
        
        public NotTriangleException() {
        
        }
    
        public NotTriangleException(String message) {
        
            super(message);
        }
    }

package com.dingjiaxiong.define;
    
    /**
     * @Projectname: BigDataStudy
     * @Classname: Triangle
     * @Author: Ding Jiaxiong
     * @Date:2023/4/27 15:17
     */
    
    public class Triangle {
        
        private double a;
        private double b;
        private double c;
    
        public Triangle(double a, double b, double c) throws NotTriangleException {
        
            if (a <= 0 || b <= 0 || c <= 0) {
        
                throw new NotTriangleException("三角形的边长必须是正数");
            }
            if (a + b <= c || b + c <= a || a + c <= b) {
        
                throw new NotTriangleException(a + "," + b + "," + c + "不能构造三角形，三角形任意两边之后必须大于第三边");
            }
            this.a = a;
            this.b = b;
            this.c = c;
        }
    
        public double getA() {
        
            return a;
        }
    
        public void setA(double a) throws NotTriangleException {
        
            if (a <= 0) {
        
                throw new NotTriangleException("三角形的边长必须是正数");
            }
            if (a + b <= c || b + c <= a || a + c <= b) {
        
                throw new NotTriangleException(a + "," + b + "," + c + "不能构造三角形，三角形任意两边之后必须大于第三边");
            }
            this.a = a;
        }
    
        public double getB() {
        
            return b;
        }
    
        public void setB(double b) throws NotTriangleException {
        
            if (b <= 0) {
        
                throw new NotTriangleException("三角形的边长必须是正数");
            }
            if (a + b <= c || b + c <= a || a + c <= b) {
        
                throw new NotTriangleException(a + "," + b + "," + c + "不能构造三角形，三角形任意两边之后必须大于第三边");
            }
            this.b = b;
        }
    
        public double getC() {
        
            return c;
        }
    
        public void setC(double c) throws NotTriangleException {
        
            if (c <= 0) {
        
                throw new NotTriangleException("三角形的边长必须是正数");
            }
            if (a + b <= c || b + c <= a || a + c <= b) {
        
                throw new NotTriangleException(a + "," + b + "," + c + "不能构造三角形，三角形任意两边之后必须大于第三边");
            }
            this.c = c;
        }
    
        @Override
        public String toString() {
        
            return "Triangle{" +
                    "a=" + a +
                    ", b=" + b +
                    ", c=" + c +
                    '}';
        }
    }

测试类

package com.dingjiaxiong.define;
    
    /**
     * @Projectname: BigDataStudy
     * @Classname: TestTriangle
     * @Author: Ding Jiaxiong
     * @Date:2023/4/27 15:17
     */
    
    public class TestTriangle {
        
        public static void main(String[] args) {
        
            Triangle t = null;
            try {
        
                t = new Triangle(2, 2, 3);
                System.out.println("三角形创建成功：");
                System.out.println(t);
            } catch (NotTriangleException e) {
        
                System.err.println("三角形创建失败");
                e.printStackTrace();
            }
    
            try {
        
                if (t != null) {
        
                    t.setA(1);
                }
                System.out.println("三角形边长修改成功");
            } catch (NotTriangleException e) {
        
                System.out.println("三角形边长修改失败");
                e.printStackTrace();
            }
        }
    }

测试结果

![在这里插入图片描述][b1fe5fd01ad748a9948c677aed04aaac.png_pic_center]

![在这里插入图片描述][1e24a5b1072c4f23a6d26ef378a93a43.png_pic_center]

[c4411eace5c4445da8ac4dc8eea41dfa.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/19c91d03256e4b08b20a1d9720fd516d.png
[b1fe5fd01ad748a9948c677aed04aaac.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/401f97dfa9c445fb930fdc33af7832cc.png
[1e24a5b1072c4f23a6d26ef378a93a43.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/86d686faa2b54482a6ee096ca60306a3.png