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
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