What does |= in Java / Android mean? (bit-wise OR assignment)

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Shortcut “or-assignment” (|=) operator in Java

I found the following example code in the Android SDK docs:

    boolean retValue = false;
    retValue |= mActionBarHelper.onCreateOptionsMenu(menu);
    retValue |= super.onCreateOptionsMenu(menu);

Can anyone show me equivalent code, to demonstrate what this does?

Note: I assume the method calls return a boolean value, so I like to see an example what this looks like as an if-else construct.

@Makoto: I didn't think there was a defined bit representation of a boolean data type. — Greg Kopff, May 10 '12 at 21:38
@GregKopff: A bitwise OR means that you're taking two sets of bits, and keeping the bits set high if and only if the bit in the same place is set high. Example: 1001 | 0110 = 1111. [Check Wikipedia for more info.](http://en.wikipedia.org/wiki/Bitwise_operation#OR) — Makoto, May 10 '12 at 21:40
@Makoto: Well understood - and for bytes, chars, shorts, ints and longs that have a defined bit representation, that makes sense. Sure a boolean can be considered 1 bit (the language uses a byte to store it), but it doesn't have a bit representation in the same way the other data types do. You can't cast a boolean to a byte and get 0x00 / 0x01 out. Yes, a bitwise operation is easy enough to conceptualise on a single bit - but for the reasons above, I'm "surprised" by it. — Greg Kopff, May 10 '12 at 21:48

score 8 · Answer 1 · answered May 10 '12 at 21:32

8

| applied to a boolean is just a simple boolean OR.

boolean retValue = false;
retValue = retValue | mActionBarHelper.onCreateOptionsMenu(menu);
retValue = retValue | super.onCreateOptionsMenu(menu);

answered May 10 '12 at 21:32

Marko Topolnik

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Mattias Isegran Bergander · Accepted Answer · 2012-05-10T21:47:50.230

Shorthand for or with myself and assign to me, though it is non-short circuit or instead of logical or. As it is available as a short version of assigning and or:ing sometimes used anyway with booleans, as there is no ||=. But important note: in this case it will call both methods even though retValue might already be true

So equivalent (logic wise) statements can be several, but some would be:

boolean a = mActionBarHelper.onCreateOptionsMenu(menu);
boolean b = super.onCreateOptionsMenu(menu);
boolean retValue =  a || b;

or

boolean retValue = mActionBarHelper.onCreateOptionsMenu(menu);
retValue = super.onCreateOptionsMenu(menu) || retValue;

What does |= in Java / Android mean? (bit-wise OR assignment)

2 Answers2