Common Mistakes
===============


    -  **Forgetting to declare your variables.**

       ::

           Histo.java:21: cannot find symbol
           symbol  : variable count
           location: class Histo
                   count = new ArrayList<Integer>(10);
                   ^

    -  **Not importing a class**:

       ::

            Histo.java:9: cannot find symbol
            symbol  : class Scanner
            location: class Histo
                    Scanner data = null;
                    ^

    -  **Forgetting to use the new keyword to create an object.** Here’s
       an example of the error message that occurs when you forget to
       use the new keyword. Notice that the message is pretty unhelpful.
       Java *thinks* you are trying to call the Method Scanner, but
       there are two problems. First Scanner is not really a method it
       is a constructor.:

       ::

            Histo.java:14: cannot find symbol
            symbol  : method Scanner(java.io.File)
            location: class Histo
                            data = Scanner(new File("test.dat"));
                                   ^

    -  **Forgetting a Semicolon**:

       ::

           Histo.java:19:
           ';' expected
                       System.exit(0);
                       ^

    -  Forgetting to declare the kind of object in a container.:

       ::

             Note: Histo.java uses unchecked or unsafe operations. Note:
             Recompile with -Xlint:unchecked for details.