Method should return boolean, returns int

Question

I have to create a method similiar to one that's inside a JAR. I have no code, so I disassabled to study. I used JD-GUI, which tells me, is: ``` private static boolean checkMe(Date paramDate, String paramString) throws REUException { int i = 1; int j, k; // unrelated stuff if (j > k) i = 0; return i; } ``` You can see in method signature it should return a `boolean`, but it really returns an `ìnt`, which is not allowed in Java So, I thought there were something wrong with JD-GUI. I tried to dissasemble using `javap`, but I still don't get a clue: Using: `javap -c -s -verbose -private Class` I get: ``` private static boolean checkMe(java.util.Date, java.lang.String) throws reu.exceptions.REUException; Signature: (Ljava/util/Date;Ljava/lang/String;)Z Code: Stack=4, Locals=7, Args_size=2 0: iconst_1 1: istore_2 2: getstatic #34; //Field iniciado:Z 5: ifne 44 8: ldc_w #35; //class reu/modulos/STDWDATES 11: dup 12: astore_3 13: monitorenter 14: getstatic #34; //Field iniciado:Z 17: ifne 32…

Accepted Answer

The JVM uses integers to represent booleans. From the JVM Specification §2.3.4:

2.3.4. The boolean Type

Although the Java Virtual Machine defines a boolean type, it only provides very limited support for it. There are no Java Virtual Machine instructions solely dedicated to operations on boolean values. Instead, expressions in the Java programming language that operate on boolean values are compiled to use values of the Java Virtual Machine int data type.

You can check this out your self:

```
$ cat Test.java
class Test {
    boolean m() {
        return true;    <------------
    }
}
$ javac Test.java 
$ javap -c Test
Compiled from "Test.java"
class Test {
  [...]

boolean m();
    Code:
       0: iconst_1      
       1: ireturn        <------------
}
```

Method should return boolean, returns int

Solution

Problem