Printing multiple ArrayList objects in separate lines in Java

Question

I have a class containing some basic info about a course and an ArrayList containing objects of student class.
Is there a smarter way of editing the toString() method in order to print out information about the course and each student (on a separate line each) then this:

public String toString() {
    System.out.println("Course " + this.name + ", Teacher: " + this.teacher;
    for (Student stud: studentList) {
        System.out.println(stud);
    }
    retutn "";

I have already set the Student class' toString() method to print Student info.

*edit: Realised I made a mistake with print(stud), so changet to println(stud)

System.out.println(stud); println

Jorge Campos
– Jorge Campos

2015-02-18 15:31:03 +00:00
Commented Feb 18, 2015 at 15:31 — Jorge Campos
– Jorge Campos, Commented Feb 18, 2015 at 15:31

aioobe · Accepted Answer · 2015-02-18 15:37:26Z

5

If you want to print one student per line, use System.out.println instead of System.out.print
You shouldn't print stuff in toString, you should just return a descriptive string.

In this case it looks like you wanted a method to print stuff, so use something else than toString. Perhaps printCourseInfo for instance:

public void printCourseInfo() {
    System.out.println("Course " + name + ", Teacher: " + teacher);
    for (Student stud: studentList) {
        System.out.println(stud);        // Note println instead of print
    }
}

Bonus part: If you're using Java 8, you could do

studentList.forEach(System.out::println);

edited Feb 18, 2015 at 15:37

answered Feb 18, 2015 at 15:32

aioobe

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2 Comments

Milan C. Over a year ago

I assumed that printing in toString should be avoided. What's stopping me from actually defining a separate print method is the instruction I was given for this homework, which asks me to modify toString in order "to provide a printout of the course information first, followed by the information of all the students contained on the array".

aioobe Over a year ago

You should then 1) use the toString as method name, 2) create a String result in the beginning of the method, and 3) change each printout to result = result + <string to append> and 4) end the method with return result

Gerralt · Accepted Answer · 2015-02-18 15:32:09Z

1

You should use System.out.println(stud) in stead of System.out.print(stud)

What the "println" does, is printing each Student on a new line

Also see this for everything on System

answered Feb 18, 2015 at 15:32

Gerralt

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Comments

freddiev4 · Accepted Answer · 2015-02-18 15:35:01Z

0

When you have a toString() method you should be returning a string, not printing it out.

Since you're using System.out.print in this case, that means you probably want to print stuff out. So change it to System.out.println in your for-each loop

public void printCourseInfo() { 
    System.out.println("Course " + name + ", Teacher: " + teacher);
    for (Student stud: studentList) {
        System.out.println(stud);    
    } 
}

answered Feb 18, 2015 at 15:35

freddiev4

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Comments

Richard · Accepted Answer · 2015-02-18 15:42:03Z

0

Others have mentioned that you shouldn't really repurpose toString(). Instead you should implement a method like 'getAsPrettyString()' etc. If you're lazy (like me) you might want to use something like this :

import java.util.List;
import org.apache.commons.lang3.builder.ReflectionToStringBuilder;

public class Blah {
    private String hello;
    private List<String>helloList;

    public String getAsPrettyString() {
        return ReflectionToStringBuilder.toString(this);
    }   
}

Using commons lang etc.

answered Feb 18, 2015 at 15:42

Richard

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