Java中try,return ,finally,throw使用总结

本文详细介绍了Java中try、catch、finally语句块的执行顺序,特别是return和throw语句在不同场景下的表现,并通过具体代码示例展示了这些概念的实际应用。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

(1) 当 try 中抛出异常且 catch 中有 return 语句, finally 中没有 return 语句, java 先执行 catch 中非 return 语句,再执行 finally 语句,最后执行 catch 中 return 语句。详见情况一。
(2) 当 try 中抛出异常且 catch 中有 return 语句, finally 中也有 return 语句, java 先执行 catch 中非 return 语句,再执行 finally 中非 return 语句,最后执行 finally 中 return 语句,函数返回值为 finally 中返回的值。详见情况二。
(3) Throw (无论是 catch 中还是非 catch 中)后面不能再跟 code ,否则编译不能通过。详见下面情况三,四,五。
Return , finally 总结:
情况一,代码如下:
public class Test {
	public int testTry() {
		FileInputStream fi = null;
		try {
			fi = new FileInputStream("");
		} catch (FileNotFoundException fnfe) {
			System.out.println("this is FileNotFoundException");
			return 1;
		} catch (SecurityException se) {
			System.out.println("this is SecurityException");
		} finally {
			System.out.println("this is finally");
		}
		return 0;
	}

	public static void main(String[] args) {
		Test t = new Test();
		System.out.println(t.testTry());
	}
}
 
Output :
this is FileNotFoundException
this is finally
1

情况二,代码修改如下:
public class Test {
	public int testTry() {
		FileInputStream fi = null;
		try {
			fi = new FileInputStream("");
		} catch (FileNotFoundException fnfe) {
			System.out.println("this is FileNotFoundException");
			return 1;
		} catch (SecurityException se) {
			System.out.println("this is SecurityException");
		} finally {
			System.out.println("this is finally");
			return 3;
		}
		// return 0;
	}

	public static void main(String[] args) {
		Test t = new Test();
		System.out.println(t.testTry());
	}
}
 
Output :
this is FileNotFoundException
this is finally
3

----------------------------------------------------
Return throw 总结:
情况三:
public class Test {
	public static void main(String[] args) {
		Test t = new Test();
		try {
			System.out.println(t.testTry());
		} catch (Exception e) {
			System.out.println("this is exception");
		}
	}

	public int testTry() throws Exception {
		FileInputStream fi = null;
		try {
			fi = new FileInputStream("");
		} catch (FileNotFoundException fnfe) {
			// System.out.println("this is FileNotFoundException");
			throw new Exception();
			return 1;
		} catch (SecurityException se) {
			System.out.println("this is SecurityException");
		} finally {
			System.out.println("this is finally");
		}
		return 0;
	}
}
 
>javac Test.java
Test.java:22: 无法访问的语句
Return 1;

情况四:
public class Test {
	public static void main(String[] args) {
		Test t = new Test();
		try {
			System.out.println(t.testTry());
		} catch (Exception e) {
			System.out.println("this is exception");
		}
	}

	public int testTry() throws Exception {
		FileInputStream fi = null;
		try {
			fi = new FileInputStream("");
		} catch (FileNotFoundException fnfe) {
			// System.out.println("this is FileNotFoundException");
			throw new Exception();
			System.out.println("after throw exception");
			// return 1;
		} catch (SecurityException se) {
			System.out.println("this is SecurityException");
		} finally {
			System.out.println("this is finally");
		}
		return 0;
	}
}
 
>javac Test.java
Test.java:22: 无法访问的语句
System.out.println("this is SecurityException");

情况五:
public class Test {
	public static void main(String[] args) {
		Test t = new Test();
		try {
			t.testTry();
		} catch (Exception e) {
			System.out.println("this is exception");
		}
	}

	public void testTry() throws Exception {
		throw new Exception();
		System.out.println("this is testTry method");
	}
}
 
>javac Test.java
Test.java:22: 无法访问的语句
System.out.println("this is testTry method");
本文来自优快云博客,转载请标明出处: http://blog.youkuaiyun.com/leigt3/archive/2010/01/15/5193091.aspx
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值