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 7
Java(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 type
0 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 /* same_locals_1_stack_item */
stack = [ class java/lang/Throwable ]
frame_type = 10 /* same */
您会注意到中的 ,一次在之前goto
,一次在之后。您还会注意到Exception table
,如果在某行发生异常,则which指定要去的语句。
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
之后执行内的所有内容goto
。如果没有异常,请执行finally
,然后goto
在finally
之后执行跳过goto
。
在所有情况下,您都将在finally
块内执行代码。
未明确处理其他异常