What is mean 'return a|b|c' in the non void java function? : <p>I'm new at java, and I'm a little confused by the functions '|' in non void java functions return</p>

<pre><code>private int donUnderstand() {
    return 1 | 2 | 3 | 4; //return 7, where is 7 come from?
}
</code></pre>

<p>Function above will return 7, but I don't get it where is 7 come from. I need some explanation. What is '|' character really mean at that function?</p>
