Java 实例 - 集合中添加不同类型元素

以下实例演示了在集合类中添加不同类型的元素：

Main.java 文件

  1. import java.util.Map;
  2. import java.util.Set;
  3. import java.util.SortedMap;
  4. import java.util.SortedSet;
  5. import java.util.TreeMap;
  6. import java.util.TreeSet;
  8. import java.util.ArrayList;
  9. import java.util.Collection;
  10. import java.util.HashMap;
  11. import java.util.HashSet;
  12. import java.util.Iterator;
  13. import java.util.LinkedHashMap;
  14. import java.util.LinkedHashSet;
  15. import java.util.LinkedList;
  16. import java.util.List;
  19. public class Main {
  20.    public static void main(String[] args) {
  21.       List lnkLst = new LinkedList();
  22.       lnkLst.add("element1");
  23.       lnkLst.add("element2");
  24.       lnkLst.add("element3");
  25.       lnkLst.add("element4");
  26.       displayAll(lnkLst);
  27.       List aryLst = new ArrayList();
  28.       aryLst.add("x");
  29.       aryLst.add("y");
  30.       aryLst.add("z");
  31.       aryLst.add("w");
  32.       displayAll(aryLst);
  33.       Set hashSet = new HashSet();
  34.       hashSet.add("set1");
  35.       hashSet.add("set2");
  36.       hashSet.add("set3");
  37.       hashSet.add("set4");
  38.       displayAll(hashSet);
  39.       SortedSet treeSet = new TreeSet();
  40.       treeSet.add("1");
  41.       treeSet.add("2");
  42.       treeSet.add("3");
  43.       treeSet.add("4");
  44.       displayAll(treeSet);
  45.       LinkedHashSet lnkHashset = new LinkedHashSet();
  46.       lnkHashset.add("one");
  47.       lnkHashset.add("two");
  48.       lnkHashset.add("three");
  49.       lnkHashset.add("four");
  50.       displayAll(lnkHashset);
  51.       Map map1 = new HashMap();
  52.       map1.put("key1", "J");
  53.       map1.put("key2", "K");
  54.       map1.put("key3", "L");
  55.       map1.put("key4", "M");
  56.       displayAll(map1.keySet());
  57.       displayAll(map1.values());
  58.       SortedMap map2 = new TreeMap();
  59.       map2.put("key1", "JJ");
  60.       map2.put("key2", "KK");
  61.       map2.put("key3", "LL");
  62.       map2.put("key4", "MM");
  63.       displayAll(map2.keySet());
  64.       displayAll(map2.values());
  65.       LinkedHashMap map3 = new LinkedHashMap();
  66.       map3.put("key1", "JJJ");
  67.       map3.put("key2", "KKK");
  68.       map3.put("key3", "LLL");
  69.       map3.put("key4", "MMM");
  70.       displayAll(map3.keySet());
  71.       displayAll(map3.values());
  72.    }
  73.    static void displayAll(Collection col) {
  74.       Iterator itr = col.iterator();
  75.       while (itr.hasNext()) {
  76.          String str = (String) itr.next();
  77.          System.out.print(str + " ");
  78.       }
  79.       System.out.println();
  80.    }
  81. }

以上代码运行输出结果为：

  1. element1 element2 element3 element4 
  2. x y z w 
  3. set3 set2 set4 set1 
  4. 1 2 3 4 
  5. one two three four 
  6. key1 key2 key3 key4 
  7. J K L M 
  8. key1 key2 key3 key4 
  9. JJ KK LL MM 
  10. key1 key2 key3 key4 
  11. JJJ KKK LLL MMM