title: How to input colored text in EditText
body: <p>I want to change the color in EditText dynamically.
  To be specific:</p>
  
  <p>After I pressed a <kbd>button</kbd>, the text I input to the <code>EditText</code> turns <strong>color red</strong>;(the text already in the EditText remains its' original color)</p>
  
  <p>After I press the <kbd>button</kbd> again , the text I input to the <code>EditText</code> turns some other color,also, the color of the text which already in the <code>EditText</code> remains. </p>