Java Collection Union union(Collection c1, Collection c2)

Description

intersection of c1 and c2, does not change input collections, returns new collection (list)

License

Open Source License

Declaration

public static <T> List<T> union(Collection<T> c1, Collection<T> c2) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.util.ArrayList;

import java.util.Collection;
import java.util.Collections;

import java.util.List;

public class Main {
    /**//  w  w  w .  jav  a2 s.co m
     * intersection of c1 and c2, does not change input collections, returns new collection (list)
     */
    public static <T> List<T> union(Collection<T> c1, Collection<T> c2) {
        if (c1 == null && c2 == null) {
            return Collections.emptyList();
        }
        if (c1 == null) {
            return new ArrayList<>(c2);
        }
        if (c2 == null) {
            return new ArrayList<>(c1);
        }
        List<T> tmp = new ArrayList<>(c1.size() + c2.size());
        tmp.addAll(c1);
        tmp.addAll(c2);
        return tmp;
    }

    public static <T> List<T> emptyList() {
        return Collections.emptyList();
    }
}

Related

1. union(Collection coll)
2. union(Collection collection1, Collection collection2)
3. union(Collection c1, Collection c2)
4. union(Collection> sets)
5. union(Collection a, Collection b)
6. union(Collection initial, Collection other)
7. union(Collection lhs, Collection rhs)
8. union(Collection set1, Collection set2)
9. union(final Collection a, final Collection b)