基础深化和提高-异常机制

package com.tong; import java.util.regex.Matcher; import java.util.regex.Pattern; //测试运行时异常和处理方式（RuntimeException） public class Test01 { public static void main(String[] args) { //ArithmeticException int b=0; if(b!=0){ System.out.println(1/b); } //NullPointerException String str=null; if(str!=null){ System.out.println(str.charAt(0)); } //ClassCastException Animal a = new Cat(); if(a instanceof Dog) { Dog d = (Dog)a; } //IndexOutOfBoundsException int[ ] arr = new int[5]; //下标范围：[0,4] int index = 5; if(index>=0&&index<arr.length){ System.out.println(arr[index]); } //NumberFormatException String str2 = "1234abcf"; // System.out.println(Integer.parseInt(str2)); Pattern p = Pattern.compile("^\\d+$"); Matcher m = p.matcher(str2); if (m.matches()) { // 如果str匹配代表数字的正则表达式,才会转换 System.out.println(Integer.parseInt(str)); } } } class Animal{ } class Dog extends Animal{ } class Cat extends Animal{ }