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
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
public class Main {
public static void main(String[] args) {
List lnkLst = new LinkedList();
lnkLst.add("element1");
lnkLst.add("element2");
lnkLst.add("element3");
lnkLst.add("element4");
displayAll(lnkLst);
List aryLst = new ArrayList();
aryLst.add("x");
aryLst.add("y");
aryLst.add("z");
aryLst.add("w");
displayAll(aryLst);
Set hashSet = new HashSet();
hashSet.add("set1");
hashSet.add("set2");
hashSet.add("set3");
hashSet.add("set4");
displayAll(hashSet);
SortedSet treeSet = new TreeSet();
treeSet.add("1");
treeSet.add("2");
treeSet.add("3");
treeSet.add("4");
displayAll(treeSet);
LinkedHashSet lnkHashset = new LinkedHashSet();
lnkHashset.add("one");
lnkHashset.add("two");
lnkHashset.add("three");
lnkHashset.add("four");
displayAll(lnkHashset);
Map map1 = new HashMap();
map1.put("key1", "J");
map1.put("key2", "K");
map1.put("key3", "L");
map1.put("key4", "M");
displayAll(map1.keySet());
displayAll(map1.values());
SortedMap map2 = new TreeMap();
map2.put("key1", "JJ");
map2.put("key2", "KK");
map2.put("key3", "LL");
map2.put("key4", "MM");
displayAll(map2.keySet());
displayAll(map2.values());
LinkedHashMap map3 = new LinkedHashMap();
map3.put("key1", "JJJ");
map3.put("key2", "KKK");
map3.put("key3", "LLL");
map3.put("key4", "MMM");
displayAll(map3.keySet());
displayAll(map3.values());
}
static void displayAll(Collection col) {
Iterator itr = col.iterator();
while (itr.hasNext()) {
String str = (String) itr.next();
System.out.print(str + " ");
}
System.out.println();
}
}
以上代码运行输出结果为：
element1 element2 element3 element4
x y z w
set3 set2 set4 set1
1 2 3 4
one two three four
key1 key2 key3 key4
J K L M
key1 key2 key3 key4
JJ KK LL MM
key1 key2 key3 key4
JJJ KKK LLL MMM暂无回复。
