JVM如何保证finally块的执行？

编译这个小程序（我意识到我应该使用您的示例，但是没关系）

public static void main(String[] args) {    try {        Float s = Float.parseFloat("0.0327f");    } finally {        System.out.println("hello");    }}

我用了

>java -version java version "1.8.0-ea"  // should be same for 7Java(TM) SE Runtime Environment (build 1.8.0-ea-b118)Java HotSpot(TM) 64-Bit Server VM (build 25.0-b60, mixed mode)

然后执行

javac -v -c <fully qualified class name>

获取字节码。您会看到类似

public static void main(java.lang.String[]);  flags: ACC_PUBLIC, ACC_STATIC  Code:    stack=2, locals=3, args_size=1       0: ldc#2       // String 0.0327f       2: invokestatic  #3       // Method java/lang/Float.parseFloat:(Ljava/lang/String;)F       5: invokestatic  #4       // Method java/lang/Float.valueOf:(F)Ljava/lang/Float;       8: astore_1       9: getstatic     #5       // Field java/lang/System.out:Ljava/io/PrintStream;      12: ldc#6       // String hello      14: invokevirtual #7       // Method java/io/PrintStream.println:(Ljava/lang/String;)V      17: goto          31      20: astore_2      21: getstatic     #5       // Field java/lang/System.out:Ljava/io/PrintStream;      24: ldc#6       // String hello      26: invokevirtual #7       // Method java/io/PrintStream.println:(Ljava/lang/String;)V      29: aload_2      30: athrow      31: return    Exception table:       from    to  target type0     9    20   any          20    21    20   any    LineNumberTable:      line 10: 0      line 12: 9      line 13: 17      line 12: 20      line 14: 31    StackMapTable: number_of_entries = 2         frame_type = 84         stack = [ class java/lang/Throwable ]         frame_type = 10 

您会注意到中的 代码

finally

goto

Exceptiontable

因此，如果在语句0-9之间发生任何异常，请转到第20行并在

finally

goto

finally

goto

finally

goto

在所有情况下，您都将在

finally

未明确处理其他异常

使用一个

finally

Exception table

Throwable

这是字节码指令的清单。