Java代码编译和反编译的那些事儿

public class switchDemoString {
 public static void main(String[] args) {
 String str = "world";
 switch (str) {
  case "hello":
  System.out.println("hello");
  break;
  case "world":
  System.out.println("world");
  break;
  default:
  break;
 }
 }
}

javac switchDemoString.java
javap -c switchDemoString.class

public class com.hollis.suguar.switchDemoString {
 public com.hollis.suguar.switchDemoString();
 Code:
 0: aload_0
 1: invokespecial #1   // Method java/lang/Object."<init>":()V
 4: return

 public static void main(java.lang.String[]);
 Code:
 0: ldc  #2   // String world
 2: astore_1
 3: aload_1
 4: astore_2
 5: iconst_m1
 6: istore_3
 7: aload_2
 8: invokevirtual #3   // Method java/lang/String.hashCode:()I
 11: lookupswitch { // 2
  99162322: 36
  113318802: 50
  default: 61
  }
 36: aload_2
 37: ldc  #4   // String hello
 39: invokevirtual #5   // Method java/lang/String.equals:(Ljava/lang/Object;)Z
 42: ifeq  61
 45: iconst_0
 46: istore_3
 47: goto  61
 50: aload_2
 51: ldc  #2   // String world
 53: invokevirtual #5   // Method java/lang/String.equals:(Ljava/lang/Object;)Z
 56: ifeq  61
 59: iconst_1
 60: istore_3
 61: iload_3
 62: lookupswitch { // 2
   0: 88
   1: 99
  default: 110
  }
 88: getstatic #6   // Field java/lang/System.out:Ljava/io/PrintStream;
 91: ldc  #4   // String hello
 93: invokevirtual #7   // Method java/io/PrintStream.println:(Ljava/lang/String;)V
 96: goto  110
 99: getstatic #6   // Field java/lang/System.out:Ljava/io/PrintStream;
 102: ldc  #2   // String world
 104: invokevirtual #7   // Method java/io/PrintStream.println:(Ljava/lang/String;)V
 107: goto  110
 110: return
}

public class switchDemoString
{
 public switchDemoString()
 {
 }
 public static void main(String args[])
 {
 String str = "world";
 String s;
 switch((s = str).hashCode())
 {
 default:
  break;
 case 99162322:
  if(s.equals("hello"))
  System.out.println("hello");
  break;
 case 113318802:
  if(s.equals("world"))
  System.out.println("world");
  break;
 }
 }
}

java -jar cfr_0_125.jar switchDemoString.class --decodestringswitch false

public class switchDemoString {
 public static void main(String[] arrstring) {
 String string;
 String string2 = string = "world";
 int n = -1;
 switch (string2.hashCode()) {
  case 99162322: {
  if (!string2.equals("hello")) break;
  n = 0;
  break;
  }
  case 113318802: {
  if (!string2.equals("world")) break;
  n = 1;
  }
 }
 switch (n) {
  case 0: {
  System.out.println("hello");
  break;
  }
  case 1: {
  System.out.println("world");
  break;
  }
 }
 }
}

java -jar cfr_0_125.jar switchDemoString.class

public class switchDemoString {
 public static void main(String[] arrstring) {
 String string;
 switch (string = "world") {
  case "hello": {
  System.out.println("hello");
  break;
  }
  case "world": {
  System.out.println("world");
  break;
  }
 }
 }
}

public static void main(String... args) {
 List<String> strList = ImmutableList.of("Hollis", "公众号：Hollis", "博客：www.hollischuang.com");

 strList.forEach( s -> { System.out.println(s); } );
}

public static /* varargs */ void main(String ... args) {
 ImmutableList strList = ImmutableList.of((Object)"Hollis", (Object)"\u516c\u4f17\u53f7\uff1aHollis", (Object)"\u535a\u5ba2\uff1awww.hollischuang.com");
 strList.forEach((Consumer<String>)LambdaMetafactory.metafactory(null, null, null, (Ljava/lang/Object;)V, lambda$main$0(java.lang.String ), (Ljava/lang/String;)V)());
}

private static /* synthetic */ void lambda$main$0(String s) {
 System.out.println(s);
}