Java 集合List、Set、HashMap操作三(查找List中的最大最小值、遍历HashTable、List元素替换、List查找位置)
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Java 集合List、Set、HashMap操作三(查找List中的最大最小值、遍历HashTable、List元素替换、List查找位置)
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查找List 中的最大最小值
以下實例演示了如何使用 Collections 類的 max() 和 min() 方法來獲取List中最大最小值:?
import java.util.*;public class Main {public static void main(String[] args) {List list = Arrays.asList("one Two three Four five six one three Four".split(" "));System.out.println(list);System.out.println("最大值: " + Collections.max(list));System.out.println("最小值: " + Collections.min(list));} }以上代碼運行輸出結果為:
[one, Two, three, Four, five, six, one, three, Four] 最大值: three 最小值: Four?
遍歷HashTable
import java.util.Enumeration; import java.util.Hashtable;public class Main {public static void main(String[] args) {Hashtable ht = new Hashtable();ht.put("1", "One");ht.put("2", "Two");ht.put("3", "Three");Enumeration e = ht.keys();while (e.hasMoreElements()){System.out.println(e.nextElement());}Enumeration ee = ht.elements();while(ee.hasMoreElements()){System.out.println(ee.nextElement());}} }以上代碼運行輸出結果為:
3 2 1 Three Two One?
集合中添加不同類型元素(各種集合添加元素)
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();} }以上代碼運行輸出結果為:
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?
List元素替換
import java.util.*;public class Main {public static void main(String[] args) {List list = Arrays.asList("one Two three Four five six one three Four".split(" "));System.out.println("List :"+list);Collections.replaceAll(list, "one", "hundrea");System.out.println("replaceAll: " + list);} }以上代碼運行輸出結果為:
List :[one, Two, three, Four, five, six, one, three, Four] replaceAll: [hundrea, Two, three, Four, five, six, hundrea, three, Four]?
List截取(查找位置)
import java.util.*;public class Main {public static void main(String[] args) {List list = Arrays.asList("one Two three Four five six one three Four".split(" "));System.out.println("List :"+list);List sublist = Arrays.asList("three Four".split(" "));System.out.println("子列表 :"+sublist);System.out.println("indexOfSubList: "+ Collections.indexOfSubList(list, sublist));System.out.println("lastIndexOfSubList: "+ Collections.lastIndexOfSubList(list, sublist));} }以上代碼運行輸出結果為:
List :[one, Two, three, Four, five, six, one, three, Four] 子列表 :[three, Four] indexOfSubList: 2 lastIndexOfSubList: 7?
總結
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