猜猜下面java程序分别会有什么样的输出？
程序：
public class Test {
public static void main(String[] args) {
System.out.println("=============test1==================");
System.out.println(test1());
System.out.println("===============================");
System.out.println("=============test1_1==================");
System.out.println(test1_1());
System.out.println("===============================");
System.out.println("\n============test2===================");
System.out.println(test2());
System.out.println("===============================");
System.out.println("\n============test2_1===================");
System.out.println(test2_1());
System.out.println("===============================");
System.out.println("\n============test3===================");
System.out.println(test3());
System.out.println("===============================");
System.out.println("\n============test3_1===================");
System.out.println(test3_1());
System.out.println("===============================");
}
public static String test1() {
String a = "in try";
try {
return a;
} catch (Exception e) {
} finally {
a = "in finally";
System.out.println("do finally");
}
return a;
}
public static String test1_1() {
String a = "in try";
try {
return a;
} catch (Exception e) {
} finally {
a = "in finally";
System.out.println("do finally");
return a;
}
}
public static int test2() {
int a = 1;
try {
return a;
} catch (Exception e) {
} finally {
a = 2;
System.out.println("do finally");
}
return a;
}
public static int test2_1() {
int a = 1;
try {
return a;
} catch (Exception e) {
} finally {
a = 2;
System.out.println("do finally");
return a;
}
}
public static Helper test3() {
Helper a = new Helper();
a.a = 1;
try {
return a;
} catch (Exception e) {
} finally {
a.a = 2;
System.out.println("do finally");
}
return a;
}
public static Helper test3_1() {
Helper a = new Helper();
a.a = 1;
try {
return a;
} catch (Exception e) {
} finally {
a.a = 2;
System.out.println("do finally");
return a;
}
}
static class Helper {
int a;
public String toString() {
return String.valueOf(a);
}
}
}
运行结果：
=============test1================== do finally in try =============================== =============test1_1================== do finally in finally =============================== ============test2=================== do finally 1 =============================== ============test2_1=================== do finally 2 =============================== ============test3=================== do finally 2 =============================== ============test3_1=================== do finally 2 ===============================
结论：
1.在try catch块里return的时候，finally也会被执行。
2.return语句会把后面的值复制到一份用来返回，如果return的是基本类型的，finally里对变量的改动将不起效果，如果return 的是引用类型的，改动将可以起效果。
3.finally里的return语句会把try catch块里的return语句效果给覆盖掉。
看来return语句并不一定都是函数的出口，执行return时，只是把return后面的值复制了一份到返回值变量里去了。看来最佳实践是：
1.最好把return放到方法尾而不要在try cath 里return
2.不要在try catch块和finally块里都包含return
3.如果在try catch块里return, 则不要在finally块里操作被return的变量