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public class CC{
public static void main(String[] args){
int a = 1;
if(a==1){
int b = 2;
System.out.println(b);
}else{
int b = 3;
System.out.println(b);
}
}
}
javac CC.java
javap -c CC
C:\Users\Administrator>javap -c CC
Compiled from "CC.java"
public class CC {
public CC();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
public static void main(java.lang.String[]);
Code:
0: iconst_1
1: istore_1
2: iload_1
3: iconst_1
4: if_icmpne 19
7: iconst_2
8: istore_2
9: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
12: iload_2
13: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
16: goto 28
19: iconst_3
20: istore_2 // 我的注释 看看虚拟机规范就可以了
21: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
24: iload_2
25: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
28: return
}
public class CC{
public static void main(String[] args){
int a = 1;
if(a==1){
int b = 2;
System.out.println(b);
}else{
b = 3;
System.out.println(b);
}
}
}
javac CC.java
CC.java:11: 错误: 找不到符号
b = 3;
^
符号: 变量 b
位置: 类 CC
CC.java:12: 错误: 找不到符号
System.out.println(b);
^
符号: 变量 b
位置: 类 CC
2 个错误
public class CC{
public static void main(String[] args){
int a = 1;
if(a==1){
int b = 2;
System.out.println(b);
}else{
int b = 3;
int c = 4;
System.out.println(b+c);
}
}
}
// javac javap 之后
C:\Users\Administrator>javap -c CC
Compiled from "CC.java"
public class CC {
public CC();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
public static void main(java.lang.String[]);
Code:
0: iconst_1
1: istore_1
2: iload_1
3: iconst_1
4: if_icmpne 19
7: iconst_2
8: istore_2
9: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
12: iload_2
13: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
16: goto 32
19: iconst_3
20: istore_2
21: iconst_4
22: istore_3
23: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
26: iload_2
27: iload_3
28: iadd
29: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
32: return
}