Create and answer a collection that is the same type, or the closest equivalent of another collection. - Java java.util

Java examples for java.util:Collection Creation

Description

Create and answer a collection that is the same type, or the closest equivalent of another collection.

Demo Code


//package com.book2s;
import java.util.*;

public class Main {
    public static void main(String[] argv) {
        Collection col = java.util.Arrays.asList("asdf", "book2s.com");
        System.out.println(createCollection(col));
    }/*from w  ww .j  a va 2 s  .c o  m*/

    /**
     * Create and answer a collection that is the same type, or the closest
     * equivalent of col.
     * 
     * @param col
     * @return
     */
    public static Collection createCollection(Collection col) {
        Collection answer;
        try {
            answer = (Collection) col.getClass().newInstance();
        } catch (Exception e) {
            if (col instanceof List) {
                answer = new ArrayList();
            } else if (col instanceof SortedSet) {
                answer = new TreeSet();
            } else if (col instanceof Set) {
                answer = new HashSet();
            } else {
                answer = new ArrayList(); // should this throw an exception?
            }
        }
        return answer;
    }
}

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