本文研究的主要是java中finally和return的关系，具体介绍和实例如下所示。
finally 和 return 关系的总结
1.try块中有system.exit(0)这样的语句，由于它是终止java虚拟机jvm的，连jvm都停止了，所有都结束了，当然finally语句也不会被执行到。
2.其它情况下，finally语句都必然会被执行。因此可以在这里执行一些资源的释放操作。
（1）finally中的return会覆盖try/catch中的renturn。
（2）在finally中写return语句会有警告，因为它会阻止函数抛出异常，而改为正常返回。
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package com.demo.test;
public class finallyandreturn {
private static void finallyandtryreturn() {
try {
system.out.println("finallyandtryreturn -> try");
return;
}
catch (exception e) {
system.out.println("finallyandtryreturn -> catch");
}
finally {
system.out.println("finallyandtryreturn -> finally");
}
}
private static void finallyandcatchreturn() {
try {
system.out.println("finallyandcatchreturn -> try");
throw new exception();
}
catch (exception e) {
system.out.println("finallyandcatchreturn -> catch");
return;
}
finally {
system.out.println("finallyandcatchreturn -> finally");
}
}
// finally语句是在try的return语句执行之后，return返回之前执行。
private static string tryreturn() {
string str = "initialized";
try {
system.out.println("tryreturn -> try");
str = "try";
return str;
}
catch (exception e) {
system.out.println("tryreturn -> catch");
str = "catch";
}
finally {
system.out.println("tryreturn -> finally");
str = "finally";
}
return null;
}
private static string tryreturnandfinallyreturn() {
string str = "initialized";
try {
system.out.println("tryreturnandfinallyreturn -> try");
str = "try";
return str;
}
catch (exception e) {
system.out.println("tryreturnandfinallyreturn -> catch");
str = "catch";
}
finally {
system.out.println("tryreturnandfinallyreturn -> finally");
/*
* warning: finally block does not complete normally
* 如果finally块中包含了return语句，即使前面的catch块重新抛出了异常，则调用该方法的语句也不会获得catch块重新抛出的异常，而是会得到finally块的返回值，并且不会捕获异常。
*/
str = "finally";
return str;
}
}
private static string trythrowandfinallyreturn() throws exception {
string str = "initialized";
try {
system.out.println("trythrowandfinallyreturn -> try");
str = "try";
throw new exception();
}
catch (exception e) {
system.out.println("trythrowandfinallyreturn -> catch");
str = "catch";
throw new exception();
}
finally {
system.out.println("trythrowandfinallyreturn -> finally");
/*
* warning: finally block does not complete normally
* 如果finally块中包含了return语句，即使前面的catch块重新抛出了异常，则调用该方法的语句也不会获得catch块重新抛出的异常，而是会得到finally块的返回值，并且不会捕获异常。
*/
str = "finally";
return str;
}
}
private static void finallyandruntimeexception() {
try {
system.out.println("finallyandruntimeexception -> try");
throw new runtimeexception();
}
catch (exception e) {
system.out.println("finallyandruntimeexception -> catch");
}
finally {
system.out.println("finallyandruntimeexception -> finally");
}
}
private static void finallyandexit() {
try {
system.out.println("finallyandexit -> try");
// system.exit(0);是终止java虚拟机jvm的，连jvm都停止了，所有都结束了，当然finally语句也不会被执行到。
system.exit(0);
}
catch (exception e) {
system.out.println("finallyandexit -> catch");
}
finally {
system.out.println("finallyandexit -> finally");
}
}
public static void main(string[] args) {
finallyandtryreturn();
system.out.println();
finallyandcatchreturn();
system.out.println();
system.out.println("tryreturn return -> " + tryreturn());
system.out.println();
system.out.println("tryreturnandfinallyreturn return -> " + tryreturnandfinallyreturn());
system.out.println();
try {
system.out.println("trythrowandfinallyreturn return -> " + trythrowandfinallyreturn());
}
catch (exception e) {
e.printstacktrace();
}
system.out.println();
finallyandruntimeexception();
system.out.println();
finallyandexit();
}
}
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演示结果：
总结
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原文链接：http://blog.csdn.net/chy555chy/article/details/52791338