java calling a method from another class

Question

I am working on a problem and I am very stuck because I am just starting to learn java  Any help I can get to understand this would be great  I have to write a program that has two classes  The main class will read from a file and uses the second class to find how may times the same words have been repeated in the file and add them to an array that contans the words and number of times the word repeated  I am ok with the reading the file part  I just can t seem to wrap my head around how to call a method from the second class to add the word into the array and increment the counter   Here is my code so far if you run it you will see how new I am to this by how many errors you will get    import java io     public class Words  public static void main  String    args        ProcessInput        System out println   nprogram finished        public static WordList ProcessInput          BufferedReader inputFile      String inputLine      String   word      WordList words          try                       inputFile new BufferedReader new FileReader   inputFile txt                 inputLine   inputFile readLine                while  inputLine   null                                word inputLine toLowerCase   split                       for  int i 0  i lt word length  i                         System out println  word i                        words addWord word i                                      inputLine   inputFile readLine                               inputFile close                      catch  IOException ioe                        System out println  ioe getMessage                 ioe printStackTrace                       return words        class WordList   String    words  int wordcount  public WordList          words  new String  1000       wordcount 0      public String  addWord  String word        words wordcount  word      wordcount  1      return words wordcount       public void printList         for  int i 0  i lt wordcount  i             System out println  words i

User · Answer

You have to initialise the object  create the object itself  in order to be able to call its methods otherwise you would get a NullPointerException   WordList words   new WordList

User · Answer

You re very close  What you need to remember is when you re calling a method from another class you need to tell the compiler where to find that method   So  instead of simply calling addWord  someWord    you will need to initialise an instance of the WordList class  e g  WordList list   new WordList      and then call the method using that  i e  list addWord  someWord      However  your code at the moment will still throw an error there  because that would be trying to call a non-static method from a static one  So  you could either make addWord   static  or change the methods in the Words class so that they re not static   My bad with the above paragraph - however you might want to reconsider ProcessInput   being a static method - does it really need to be

[java] java calling a method from another class

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