static example

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ClassObj.java
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import java.util.Arrays;

public class ClassObj {
    private static final int MAX_STUDENTS = 30;
    private String[] students = new String[MAX_STUDENTS];
    private int numOfStudents = 0;

    public int getNumOfStudents(){
        return this.numOfStudents;
    }

    public boolean addStudent(String student){
        if(numOfStudents==MAX_STUDENTS){
            return false;
        }
        students[numOfStudents] = student;
        numOfStudents += 1;
        return true;
    }

    public String[] getStudents() {
        return Arrays.copyOf(students, students.length);
    }

    @Override
    public String toString() {
        return "This class has "+numOfStudents+" students. out of a possible "+MAX_STUDENTS;
    }

    public static int getMaxStudents(){
        return MAX_STUDENTS;
    }
}




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Tester.java
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public class Tester {
    public static void main(String[] args){

        System.out.println(ClassObj.getMaxStudents());


        ClassObj myclass = new ClassObj();

        System.out.println(myclass.getNumOfStudents());
        myclass.addStudent("tzahi");

        System.out.println(myclass.getNumOfStudents());

        System.out.println(ClassObj.getMaxStudents());

        System.out.println(myclass);

        /*
        ClassObj.MAX_STUDENTS = 10;

        System.out.println(myclass);
        */



    }
}