Java 1.6 Array to list / List to Set / Set to Map

程式碼：

import java.util.*;

public class Test {

    private String[] listToArray(List<String> list) {
        return list.toArray(new String[list.size()]);
    }

    private List<String> arrayToList(String[] array) {
        return Arrays.asList(array);
    }

    private Set<String> listToSet(List<String> list) {
        return new HashSet<String>(list);
    }

    private List<String> setToList(Set<String> set) {
        return new ArrayList<String>(set);
    }

    private Set<String> mapToSet(Map<String, String> map) {
        return new HashSet<String>(map.values());
    }

    private Map<String, String> setToMap(Set<String> set) {
        Map<String, String> map = new HashMap<String, String>();
        map.put(set.iterator().next(), set.iterator().next());
        return map;
    }

    private List<String> mapToList(Map<String, String> map) {
        return new ArrayList<String>(map.values());
    }

    private Map<String, String> listToMap(List<String> list) {
        Map<String, String> map = new HashMap<String, String>();
        map.put(list.iterator().next(), list.iterator().next());
        return map;
    }

}