Java学习(异常类练习题)

 练习题:

1.计算圆的面积,半径不能为零和负数

package com.oracle.Demo01;

public class Demo02 {
// 写一个计算圆的面积的方法,传一个半径,返回面积
public static void main(String[] args) {
double s=0;
s = area(-4);
System.out.println(s);
}
public static double area(double r){
try {
if(r<=0){
throw new RuntimeException(); //RuntimeException 运行异常,不会声明,不会处理异常,直接报错并且停止
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
double s=Math.PI*r*r;
return s;
}
}

 2.求平均数,参数不能为负数

package com.oracle.Demo01;

import java.util.Scanner;

public class Demo03 {
//现在要创建一个检测负数的异常类,如果是正数,则抛出异常
public static void main(String[] args){
/*double s=0;
s = area(9);
System.out.println(s);*/
//输入任意参数,求平均数
double s=avg(1,9,6,5,2);
System.out.println(s);
}
public static double area(double r){
if(r<=0){
throw new FuShuException("你传了一个负数"); //报异常并传递自定义的字符串
}
double s=Math.PI*r*r;
return s;
}
//求平均数的方法
public static double avg(double...arr){
double sum=0;
for(double i:arr){
if(i<0){
throw new FuShuException("参数为负数");
}
sum=sum+i;
}
return sum/arr.length;
}
}

自定义FuShuExecption类:

package com.oracle.Demo01;
//自定义类异常,继承自运行异常
public class FuShuException extends RuntimeException {
FuShuException(String mes){
super(mes);
}
}

 3.检测年龄不能为负数和大于200岁

测试类:

package com.oracle.Demo01;

public class Demo04 {
public static void main(String[] args) throws NoAgesException {
method("阿易",110);
}
public static void method(String name,int age) throws NoAgesException{
Person p=new Person(name,age);
if(p.getAge()<0||p.getAge()>200){
throw new NoAgesException("年龄数值非法");
}
System.out.println(p.getName()+"..."+p.getAge());
}
}

 Person类:

package com.oracle.Demo01;

public class Person {
private String name;
private int age;
Person(){ }
Person(String name,int age){
this.name=name;
this.age=age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
} }

 自定义NoAgeExecption类:

package com.oracle.Demo01;

public class  NoAgesException extends Exception {
NoAgesException(){ //声明父类的异常方法
super();
}
NoAgesException(String mes){
super(mes);
} }
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