How to return a copy of an array? [duplicate]

Question

This question already has answers here:

Make copy of an array (11 answers)

Closed 8 years ago.

 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.

Answer 1

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

Answer 2

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

Answer 3

try this:

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

Answer 4

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;
}

Answer 5

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

Answer 6

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

OR

You can also use System.arraycopy().

Answer 7

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.