JAVSE_day05_JAVA中的异常处理机制(Exception)

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原创最新推荐文章于 2026-01-30 08:00:00 发布 1.2k 阅读 AI 写同款· GEO 优化 ›

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错误(程序员不可控制):StackOverflowError:

package com.anonymous.javase.day05;

public class Demo1 {
	public static void main(String[] args) {
		Demo1.main(args);
		/*Exception in thread "main" java.lang.StackOverflowError*/
		//递归异常
	}
}

常见的几种异常:

NullPointException/ArraysindexOutOfBoundException/NumberFormatException等等....

package com.anonymous.javase.day05;

public class Demo2 {
	public static void main(String[] args) {
		//NullPointException空指针异常
		NullPointExceptionTest();
		
		//ArraysindexOutOfBoundException数组索引越界
		ArraysindexOutOfBoundExceptionTest();
		
		//NumberFormatExceptionTest()数字格式化异常
		NumberFormatExceptionTest();
		
	}
	
	public static void NullPointExceptionTest(){
		String[] str = null;
		System.out.println(str.length);
		/*Exception in thread "main" java.lang.NullPointerException*/
	}
	
	public static void ArraysindexOutOfBoundExceptionTest(){
		String[] str = {"3","4"};
		System.out.println(str[3]);
		/*Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3*/
	}
	
	public static void NumberFormatExceptionTest(){
		Integer valueOf = Integer.valueOf("345lsfds");
		System.out.println(valueOf);
		/*Exception in thread "main" java.lang.NumberFormatException: For input string: "345lsfds"*/
	}
}

try.....catch(捕获异常.处理异常)

public static void NullPointerExceptionTest(){
		String[] str = null;
		try{
			System.out.println(str.length);
		}catch(NullPointerException e){
			//获取异常信息
			System.out.println(e.getMessage());
			//获取异常信息类型
			System.out.println(e.toString());
			//获取异常信息.并跟踪异常信息位置
			e.printStackTrace();
		}
		/*Exception in thread "main" java.lang.NullPointerException*/
	}

捕获多层异常:

package com.anonymous.javase.day05;

public class Demo3 {
	//捕获多层异常
	/**
	 *	有时候不知道会出现什么样的异常,可以将异常归于Exception统一处理异常信息 
	 */
	public static void main(String[] args) {
		try{
			int sum = Integer.parseInt(null);
			double d = 10 / sum;
			System.out.println(d);
		}catch(NumberFormatException e){
			System.out.println(e.getMessage());
		}catch(ArithmeticException e){
			System.out.println(e.getMessage());
		}catch(Exception e){
			System.out.println("网络异常!");
		}
	}
}

package com.anonymous.javase.day05;

public class Demo4 {
	//使用finally
	public static void main(String[] args) {
		try {
			System.out.println(100/10);
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			System.out.println("执行该程序!");
		}
		/*java.lang.ArithmeticException: / by zero
		at com.anonymous.javase.day05.Demo4.main(Demo4.java:7)
		执行该程序!(无论什么情况下,改程序都会执行)
		*/
		
		//面试题
		int test1 = test1();
		int test2 = test2();
		System.out.println(test2);
		System.out.println(test1);
	}

	private static int test2() {
		try{
			return 10;	
		}finally{
			return 100;
		}
	}

	private static int test1() {
		int a = 1;
		try{
			return 
					a;
		}finally{
			return ++a;
			//和a++和++a道理差不多
		}
	}
}