怎么用手机创建网站,成都做网站,广厦建设集团官方网站,泰州建设局网站Synthetic是人造#xff0c;合成的意思#xff0c;在虚拟机很多地方使用ACC_SYNTHETIC表示编译器自动生成的#xff0c;区别于我们自己写的程序代码。这样说可能比较模糊#xff0c;我们举个例子#xff1a;我们创建一个内部类#xff0c;如下
public class TestInnerCl…Synthetic是人造合成的意思在虚拟机很多地方使用ACC_SYNTHETIC表示编译器自动生成的区别于我们自己写的程序代码。这样说可能比较模糊我们举个例子我们创建一个内部类如下
public class TestInnerClass {public void say(String msg) {System.out.println(msg);}class InnerClass {public void sayInner() {say(hello);}}
}
我们用javap看一下内部类InnerClass反编译之后的情况 完整如下
Classfile /F:/demo/mallsystem/provider/target/classes/com/mall/test/TestInnerClass$InnerClass.classLast modified 2024-11-28; size 638 bytesMD5 checksum 9f5efd7b8d0ad50545773d2a0e198f60Compiled from TestInnerClass.java
class com.mall.test.TestInnerClass$InnerClassminor version: 0major version: 52flags: ACC_SUPER
Constant pool:#1 Fieldref #5.#22 // com/mall/test/TestInnerClass$InnerClass.this$0:Lcom/mall/test/TestInnerClass;#2 Methodref #6.#23 // java/lang/Object.init:()V#3 String #24 // hello#4 Methodref #25.#26 // com/mall/test/TestInnerClass.say:(Ljava/lang/String;)V#5 Class #27 // com/mall/test/TestInnerClass$InnerClass#6 Class #28 // java/lang/Object#7 Utf8 this$0#8 Utf8 Lcom/mall/test/TestInnerClass;#9 Utf8 init#10 Utf8 (Lcom/mall/test/TestInnerClass;)V#11 Utf8 Code#12 Utf8 LineNumberTable#13 Utf8 LocalVariableTable#14 Utf8 this#15 Utf8 InnerClass#16 Utf8 InnerClasses#17 Utf8 Lcom/mall/test/TestInnerClass$InnerClass;#18 Utf8 sayInner#19 Utf8 ()V#20 Utf8 SourceFile#21 Utf8 TestInnerClass.java#22 NameAndType #7:#8 // this$0:Lcom/mall/test/TestInnerClass;#23 NameAndType #9:#19 // init:()V#24 Utf8 hello#25 Class #29 // com/mall/test/TestInnerClass#26 NameAndType #30:#31 // say:(Ljava/lang/String;)V#27 Utf8 com/mall/test/TestInnerClass$InnerClass#28 Utf8 java/lang/Object#29 Utf8 com/mall/test/TestInnerClass#30 Utf8 say#31 Utf8 (Ljava/lang/String;)V
{final com.mall.test.TestInnerClass this$0;descriptor: Lcom/mall/test/TestInnerClass;flags: ACC_FINAL, ACC_SYNTHETICcom.mall.test.TestInnerClass$InnerClass(com.mall.test.TestInnerClass);descriptor: (Lcom/mall/test/TestInnerClass;)Vflags:Code:stack2, locals2, args_size20: aload_01: aload_12: putfield #1 // Field this$0:Lcom/mall/test/TestInnerClass;5: aload_06: invokespecial #2 // Method java/lang/Object.init:()V9: returnLineNumberTable:line 12: 0LocalVariableTable:Start Length Slot Name Signature0 10 0 this Lcom/mall/test/TestInnerClass$InnerClass;0 10 1 this$0 Lcom/mall/test/TestInnerClass;public void sayInner();descriptor: ()Vflags: ACC_PUBLICCode:stack2, locals1, args_size10: aload_01: getfield #1 // Field this$0:Lcom/mall/test/TestInnerClass;4: ldc #3 // String hello6: invokevirtual #4 // Method com/mall/test/TestInnerClass.say:(Ljava/lang/String;)V9: returnLineNumberTable:line 14: 0line 15: 9LocalVariableTable:Start Length Slot Name Signature0 10 0 this Lcom/mall/test/TestInnerClass$InnerClass;
}
SourceFile: TestInnerClass.java
InnerClasses:#15 #5 of #25; //InnerClassclass com/mall/test/TestInnerClass$InnerClass of class com/mall/test/TestInnerClass
重点看下面标记的ACC_SYNTHETIC标记出现了 这里编译器在内部类生成了一个TestInnerClass的引用对象this$0因为是编译器自动合成的所以标记了ACC_SYNTHETIC。
而下面是内部类的构造方法可以看到它传入了外部类的实例对象之后把它赋值给this$0
aload_0默认是实例方法第一个参数是this即内部类自己的引用
aload_1则是加载第一个入参也就是外部类实例对象
putfield #1就是把外部实例设置给this$0 所以这也就解释了为什么内部类创建需要外部类对象创建了如果外部类对象还没有生成怎么传给内部类的构造方法呢
而我们内部类能调用外部类的方法也正是通过外部类的实例对象调用的
