You cannot call any instance methods on a null variable. Check for null first like this: if (myString != null && !myString.equals("")) ... ... <看更多>

Rule N° 1 Ban all NullPointerExceptions! Watch full video to know how to check for null, empty and blank Strings in java and the order in ... ... <看更多>

Note that in Java 6 and later, the String class has an isEmpty method that checks whether a string is empty. If the codebase does not need to support Java 5 ... ... <看更多>

I use to initialize my new strings like String a=null , so in my code there remains a probability to get NullPointerException if I forget to ... ... <看更多>