Converting Boolean to Integer in Java without If-Statements

Question

I\'m wondering if there\'s a way to convert a boolean to an int without using if statements (as not to break the pipeline). For example, I could write

int bo         


        

Answer 1

You can't use a boolean other than in a if. However it does not mean that there will be a branch at the assembly level.

If you check the compiled code of that method (by the way, using return b ? 1 : 0; compiles to the exact same instructions), you will see that it does not use a jump:

0x0000000002672580: sub    $0x18,%rsp
0x0000000002672587: mov    %rbp,0x10(%rsp)    ;*synchronization entry
0x000000000267258c: mov    %edx,%eax
0x000000000267258e: add    $0x10,%rsp
0x0000000002672592: pop    %rbp
0x0000000002672593: test   %eax,-0x2542599(%rip)        # 0x0000000000130000
                                                ;   {poll_return}
0x00000000025b2599: retq  

Note: this is on hotspot server 7 - you might get different results on a different VM.

Answer 2

You can use the ternary operator:

return b ? 1 : 0;

If this is considered an "if", and given this is a "puzzle", you could use a map like this:

return new HashMap<Boolean, Integer>() {{
    put(true, 1);
    put(false, 0);
}}.get(b);

Although theoretically the implementation of HashMap doesn't need to use an if, it actually does. Nevertheless, the "if" is not in your code.

Of course to improve performance, you would:

private static Map<Boolean, Integer> map = new HashMap<Boolean, Integer>() {{
    put(true, 1);
    put(false, 0);
}};

Then in the method:

return map.get(b);

Answer 3

Use the ?: operator: ( b ? 1 : 0 )

Answer 4

Otherwise, you could use the Apache Commons BooleanUtils.toInteger method which works like a charm...

// Converts a boolean to an int specifying the conversion values.    
static int  toInteger(boolean bool, int trueValue, int falseValue)

// Converts a Boolean to an int specifying the conversion values.
static int  toInteger(Boolean bool, int trueValue, int falseValue, int nullValue)

Answer 5

I found a solution by framework. Use compare for Boolean.

// b = Your boolean result
// v will be 1 if b equals true, otherwise 0
int v = Boolean.compare(b, false);

Answer 6

Since you want no if / else solution your expression is perfect, though I would slightly change it

int myint = Boolean.valueOf( bool ).compareTo( Boolean.FALSE );

There is no object creation involved, Boolean.valueOf(boolean b) returns either Boolean.TRUE or Boolean.FALSE, see API