如何在Java中将类型为String的用户输入添加到ArrayList？

Question

I am attempting to make a course registration system and one of my classes (Course) is centered around course attributes (ie. Course number, course name, instructors, students). I am making an ArrayList so that the Administrator (one of the user types) may add as many instructors to the course as he/she would like- I have created a Scanner and a String variable and everything, but when I write the .add command, Eclipse highlights ".add" and says "the method .add() is undefined for the type of scanner". Now, I can understand this, but I have no idea how to fix it and I've tried so many ideas.

Here is the method:`

public static String Instructor(){
        String courseInstructors;

        System.out.println("Please add name(s) of course instructors.");
        ArrayList<String> Instructors= new ArrayList<String>();
        Scanner courseInst = new Scanner(System.in);
        courseInstructors = courseInst.next();
        //courseInst.add(courseInstructors); 

        for(String courseInstructors1 : Instructors) {
            courseInstructors1 = courseInstructors;
            courseInst.add(courseInstructors1);
        }

        return;
    }`

Answer 1

Please adhere to Java naming conventions ad use lower case for variable names - instructors instead of Instructors .

Also, you want to add to your arraylist, so call add() on

instructors.add(courseInstructors1)

You may also want to consider choosing better variable naming than courseInstructors1 , for instance just courseInstructor , since you are referring to on instructor of all instructors .

Also in your for loop you are doing the following

for(String courseInstructors1 : Instructors) {
    courseInstructors1 = courseInstructors;
    courseInst.add(courseInstructors1);
}

This can be simplified to

for(String courseInstructors1 : Instructors) {
    courseInst.add(courseInstructors);
}

And if you look at the simplification you will see that iterating through Instructors make no sense here, since you are not using the contents of courseInstructors1.

Answer 2

I'm trying to understand what your loop is for.

if you are trying to get multiple instructor names from one input then you need something like this.

//get input
//"John Peggy Adam blah blah"
courseInstructors = courseInst.next();

//split the string by white space
String[] instArr = courseInstructors.split(" ");
//will give array of John, Peggy, Adam, blah, blah

Then do your foreach loop to add them to the list.

for(String inst: instArr){
    instructors.add(inst);
}

Otherwise I would suggest doing something like this so you don't have to worry about splitting names and such.

courseInstructor = courseInst.nextLine();

while(!courseInstructor.equals("done"){
    //add name to list of instructors.
    instructors.add(courseInstructor);
    //get next name.
    courseInstructor = courseInt.nextLin();
    //if the user types done, it will break the loop.
    //otherwise come back around and add it and get next input.
}