通过 .class文件查找答案
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?
public StringTest(); 0 aload_0 [this] 1 invokespecial java.lang.Object() [8] 4 return Line numbers: [pc: 0, line: 8] Local variable table: [pc: 0, pc: 5] local: this index: 0 type: com.sunsmile.StringTest // Method descriptor #15 ([Ljava/lang/String;)V // Stack: 3, Locals: 5 public static void main(java.lang.String[] args); 0 new java.lang.StringBuilder [16] 3 dup 4 invokespecial java.lang.StringBuilder() [18] 7 aconst_null 8 invokevirtual java.lang.StringBuilder.append(java.lang.Object) : java.lang.StringBuilder [19] 11 ldc <String "a"> [23] 13 invokevirtual java.lang.StringBuilder.append(java.lang.String) : java.lang.StringBuilder [25] 16 invokevirtual java.lang.StringBuilder.toString() : java.lang.String [28] 19 astore_1 [a] 20 new java.lang.StringBuilder [16] 23 dup 24 invokespecial java.lang.StringBuilder() [18] 27 aconst_null 28 invokevirtual java.lang.StringBuilder.append(java.lang.Object) : java.lang.StringBuilder [19] 31 ldc <String "a"> [23] 33 invokevirtual java.lang.StringBuilder.append(java.lang.String) : java.lang.StringBuilder [25] 36 invokevirtual java.lang.StringBuilder.toString() : java.lang.String [28] 39 astore_2 [aa] 40 getstatic java.lang.System.out : java.io.PrintStream [32] 43 aload_1 [a] 44 aload_2 [aa] 45 if_acmpne 52 48 iconst_1 49 goto 53 52 iconst_0 53 invokevirtual java.io.PrintStream.println(boolean) : void [38] 56 ldc <String "nulla"> [44] 58 astore_3 [b] 59 ldc <String "nulla"> [44] 61 astore 4 [bb] 63 getstatic java.lang.System.out : java.io.PrintStream [32] 66 aload_3 [b] 67 aload 4 [bb] 69 if_acmpne 76 72 iconst_1 73 goto 77 76 iconst_0 77 invokevirtual java.io.PrintStream.println(boolean) : void [38] 80 return?
