How to call a method from another class, which is in another .java file?

Question

The teacher gave us a .java file in which there is a method that I need to use in order to solve my question.

Here's the question : Call the method countEnglishWords() given in the file SentenceChecker. This method takes as input a String and outputs the number of English words it contains.

My problem is that I do not know how to call a method which is in another class which is in another .java file!

Answer 1

you must ensure that the class & method you're trying to call have appropriate access modifiers (e.g. public). Then from your class' file, you may import the SentenceChecker class at the top.

String str = "Lorem ipsum dolor sit amet your mom";
SentenceChecker sc = new SentenceChecker();
sc.countEnglishWords(str); // this will call, you could assign any ret result to variable

edit: you don't necessarily need import statement (i.e. files are in same dir).

1. Put your sentence checker in some empty dir, say "/CheckerProgram"
2. Create MySentenceCheckerCaller.java in same directory

3. Edit MySentenceCheckerCaller.java to:

   public class MySentenceCheckerCaller {
     public static void main(String[] args) {
        String str = "Lorem ipsum dolor sit amet your mom";
        SentenceChecker sc = new SentenceChecker();
        int wordCount = sc.countEnglishWords(str); // call method, assumes returns an int
        System.out.println("There are " + wordCount + " words in my string.");
      }
    }
   

4. Compile MySentenceCheckerCaller.java and SentenceChecker.java
5. Ensure that you have MySentenceCheckerCaller.class and SentenceChecker.class in program directory
6. Run java MySentenceCheckerCaller in terminal