title: Java equals plus operator
body: <p>I need to explain this strange operator <strong>=+</strong> (equal plus)</p>
  
  <p>Example #1:</p>
  
  <pre><code>Double a = new Double(5);
  Double b = new Double(10);
  a += b
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>a=15.0
  b=10.0
  </code></pre>
  
  <p>Example #2:</p>
  
  <pre><code>Double a = new Double(5);
  Double b = new Double(10);
  a =+ b
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>a=10.0
  b=10.0
  </code></pre>
  
  <p>I understand the first example, but please explain me what this <strong>=+</strong> operator did in example no.2.</p>
  
  <p>And another interesting fact is, that these operators are valid and compilable:
  +=, -=, *=, /=<br>
  but any of these two won't compile:
  =*, =/</p>