How to return a copy of an array?

Question

 public void addStudent(String student) {
    String [] temp = new String[students.length * 2];
    for(int i = 0; i < students.length; i++){
    temp[i] = students[i];
        }
    students = temp;
    students[numberOfStudents] = student;
    numberOfStudents++;

 }

public String[] getStudents() {
    String[] copyStudents = new String[students.length];

    return copyStudents;

}

I'm trying to get the method getStudents to return a copy of the array that I made in the addStudent method. I'm not sure how to go about this.

copyStudents=students.clone(); http://stackoverflow.com/questions/14149733/clone-method-for-java-arrays — amudhan3093, Feb 11 '14 at 07:15

score 12 · Accepted Answer · edited May 23 '17 at 11:48

1) Arrays.copyOf

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

2 System.arraycopy

public String[] getStudents() {
   String[] copyStudents = new String[students.length];
   System.arraycopy(students, 0, copyStudents, 0, students.length); 
   return copyStudents;
}

3 clone

public String[] getStudents() {
   return students.clone();
}

Also see the answer about performance of each approach. They are pretty the same

score 1 · Answer 2 · answered Feb 11 '14 at 07:09

1

System.arraycopy(students, 0, copyStudents, 0, students.length);

answered Feb 11 '14 at 07:09

Stewart

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1

so then I would say return copyStudents; ? – Frightlin Feb 11 '14 at 07:12

score 1 · Answer 3 · answered Feb 11 '14 at 07:10

1

try this:

System.arraycopy(students, 0, copyStudents, 0, students.length);

answered Feb 11 '14 at 07:10

score 1 · Answer 4 · answered Feb 11 '14 at 07:10

1

Java's System class provides a utility method to this:

public String[] getStudents() {
    String[] copyStudents = new String[students.length];
    System.arraycopy(students, 0, copyStudents, 0, students.length );

    return copyStudents;
}

answered Feb 11 '14 at 07:10

Mureinik

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score 0 · Answer 5 · edited May 23 '17 at 11:48

0

System.arraycopy(Object source, int startPosition, Object destination, int startPosition, int length);

More information in docu and of course, have been asked trilion times here on SO, for example here

edited May 23 '17 at 11:48

Community

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answered Feb 11 '14 at 07:11

1ac0

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score 0 · Answer 6 · answered Feb 11 '14 at 07:11

0

You can use Arrays.copyOf() to create a copy of your array.

OR

You can also use System.arraycopy().

answered Feb 11 '14 at 07:11

Ankur Shanbhag

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score 0 · Answer 7 · answered Feb 11 '14 at 07:12

0

You can use Arrays.copyOf() .

Eg:

int[] arr=new int[]{1,4,5}; 
Arrays.copyOf(arr,arr.length); // here first argument is current array
                               // second argument is size of new array.

answered Feb 11 '14 at 07:12

Ruchira Gayan Ranaweera

34,993
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How to return a copy of an array?

7 Answers7