CODEWITHSUNDEEP
java
John Gowers
John Gowers

Reputation: 2736

Why are my bitwise operations not working with `int`s in Java?

I just got the following compiler error: 

./package/path/FrameScreenPosition.java:80: incompatible types
found   : int
required: boolean
    if (frame.getExtendedState() & Frame.MAXIMIZED_BOTH) {
                                 ^

An 'extended state' is a bitwise mask of various different states such as maximized or iconified, and I'm trying to test whether the frame is maximized. The following short example produces a similar error: 

public class BitTest
{
  public static void main(String[] args)
  {
    int a = 1;
    int c = 3;

    if (a & c) {
      System.out.println("This is right.");
    }
  }
}

Everything I've seen suggests that the bitwise operator & isn't restricted to boolean variables in Java, so why am I getting an error message?

Upvotes: 3

Views: 1065

Answers (3)

arshajii
arshajii

Reputation: 129477

The expression inside if must explicitly be a boolean (that is, boolean or Boolean -- see JLS §14.9 for further details):

if ((a & c) != 0) {

Also note that the second set of parenthesis are required here since != has a higher precedence than &.

Upvotes: 15

Esko
Esko

Reputation: 29367

In Java if(..) clause must always evaluate to a boolean which is its own type unlike in, say, C.

So, 0, null etc. are not converted to boolean false nor positive numbers to true and so on and so forth. You must include arithmetic comparison operator to specify what you really want.

Upvotes: 3

JNL
JNL

Reputation: 4703

if (a & c)  wont work here;

if(condition) needs to have a boolean value.

Upvotes: 1

Related Questions