title: How to check a string that not empty in java?
body: <p>How to check a string in java that is empty or not?</p>
  
  <p>For example :
  <code>string str = "   "</code> and <code>string str2 = " "</code> and <code>str3 = ""</code></p>
  
  <p>str includes 3 spaces, str2 includes 1 space, and str3 has no characters but all of them are empty.</p>
  
  <p>How do I check this in Android?</p>