How do you call method in Java from another class to set a teacher's name in a classroom?

General Discussions
1

I have two classes: classroom and School. I want to write a method in the School class that calls public void setTeacherName(String newTeacherName) from the classroom class.

Here’s my classroom class:

public class classroom {  
    private String classRoomName;  
    private String teacherName;  

    public void setClassRoomName(String newClassRoomName) {  
        classRoomName = newClassRoomName;  
    }  

    public String returnClassRoomName() {  
        return classRoomName;  
    }  

    public void setTeacherName(String newTeacherName) {  
        teacherName = newTeacherName;  
    }  

    public String returnTeacherName() {  
        return teacherName;  
    }  
}

And my School class:

import java.util.ArrayList;  

public class School {  
    private ArrayList<classroom> classrooms;  
    private String classRoomName;  
    private String teacherName;  

    public School() {  
        classrooms = new ArrayList<classroom>();  
    }  

    public void addClassRoom(classroom newClassRoom, String theClassRoomName) {  
        classrooms.add(newClassRoom);  
        classRoomName = theClassRoomName;  
    }  

    // How do I write a method to add a teacher to the classroom using  
    // the classroom parameter and the teacher’s name?  
}

How can I properly call setTeacherName from classroom within School?

2

The simplest way is to iterate through the classrooms list, find the correct classroom, and set the teacher’s name:

public void assignTeacherToClassroom(String classRoomName, String teacherName) {  
    for (classroom cls : classrooms) {  
        if (cls.returnClassRoomName().equals(classRoomName)) {  
            cls.setTeacherName(teacherName);  
            System.out.println("Teacher " + teacherName + " assigned to " + classRoomName);
            return;  
        }  
    }  
    System.out.println("Classroom " + classRoomName + " not found!");  
}

:heavy_check_mark: Pros:

  • Simple and easy to understand.
  • Works well when classrooms are stored in a list.

:x: Cons:

  • Performance can be slow if the list is large.
3

Instead of iterating through a list every time, let’s use a HashMap<String, classroom> for quick access.

:small_blue_diamond: Modify your School class to store classrooms in a HashMap:

import java.util.HashMap;

public class School {  
    private HashMap<String, classroom> classroomMap;  

    public School() {  
        classroomMap = new HashMap<>();  
    }  

    public void addClassRoom(classroom newClassRoom, String theClassRoomName) {  
        classroomMap.put(theClassRoomName, newClassRoom);  
    }  

    public void assignTeacherToClassroom(String classRoomName, String teacherName) {  
        classroom cls = classroomMap.get(classRoomName);
        if (cls != null) {  
            cls.setTeacherName(teacherName);  
            System.out.println("Teacher " + teacherName + " assigned to " + classRoomName);
        } else {  
            System.out.println("Classroom " + classRoomName + " not found!");  
        }  
    }  
}

:heavy_check_mark: Pros:

  • Faster lookups (O(1) complexity).

  • More efficient for large schools with many classrooms.

:x: Cons:

  • Uses more memory due to the HashMap.
4

You can also directly pass a classroom object to the method.

public void assignTeacherToClassroom(classroom cls, String teacherName) {  
    if (cls != null) {  
        cls.setTeacherName(teacherName);  
        System.out.println("Teacher " + teacherName + " assigned to " + cls.returnClassRoomName());
    } else {  
        System.out.println("Invalid classroom reference!");  
    }  
}

Usage Example:

public static void main(String[] args) {  
    School mySchool = new School();  
    classroom mathClass = new classroom();  
    mathClass.setClassRoomName("Math101");  

    mySchool.addClassRoom(mathClass, "Math101");  

    mySchool.assignTeacherToClassroom(mathClass, "Mrs. Williams");  

    System.out.println("Teacher for Math101: " + mathClass.returnTeacherName());  
}

:heavy_check_mark: Pros:

  • Avoids unnecessary lookups.

  • Clean and straightforward.

:x: Cons:

  • Requires an already-referenced classroom object.