浣滆咃紙KaedeV錛?br>
JDK1.5
1.1. JAVA娉涘瀷
鍏跺疄JAVA鐨勬硾鍨嬪氨鏄垱寤轟竴涓敤綾誨瀷浣滀負鍙傛暟鐨勭被銆傚氨璞℃垜浠啓綾葷殑鏂規硶涓鏍鳳紝鏂規硶鏄繖鏍風殑method(String str1,String str2 ),鏂規硶涓弬鏁?/span>str1銆?/span>str2鐨勫兼槸鍙彉鐨勩傝屾硾鍨嬩篃鏄竴鏍風殑錛岃繖鏍峰啓class Java_Generics<K,V>錛岃繖閲岃竟鐨?/span>K鍜?/span>V灝辮薄鏂規硶涓殑鍙傛暟str1鍜?/span>str2,涔熸槸鍙彉銆備笅闈㈢湅鐪嬩緥瀛愶細
//code list 1
import java.util.Hashtable;
class TestGen0<K,V>{
public Hashtable<K,V> h=new Hashtable<K,V>();
public void put(K k, V v) {
h.put(k,v);
}
public V get(K k) {
return h.get(k);
}
public static void main(String args[]){
TestGen0<String,String> t=new TestGen0<String,String>();
t.put("key", "value");
String s=t.get("key");
System.out.println(s);
}
}
姝ｇ‘杈撳嚭:value
榪欏彧鏄釜渚嬪瓙錛?/span>JAVA涓?/span>闆嗗悎妗嗘灦閮芥硾鍨嬪寲浜嗭紝榪欓噷璐逛簡2閬嶄簨J錛夛紝涓嶈繃鐪嬬湅鏄笉鏄垱寤轟竴涓敤綾誨瀷浣滀負鍙傛暟鐨勭被錛屽弬鏁版槸K錛?span lang="EN-US">V錛屼紶鍏ョ殑“鍊?#8221;鏄?span lang="EN-US">String綾誨瀷銆傝繖涓被浠栨病鏈夌壒瀹氱殑寰呭鐞嗗瀷鍒紝浠ュ墠鎴戜滑瀹氫箟濂戒簡涓涓被錛屽湪杈撳叆杈撳叆鍙傛暟鏈夋墍鍥哄畾錛屾槸浠涔堝瀷鍒殑鏈夎姹傦紝浣嗘槸鐜板湪緙栧啓紼嬪簭錛屽畬鍏ㄥ彲浠ヤ笉鍒跺畾鍙傛暟鐨勭被鍨嬶紝鍏蜂綋鐢ㄧ殑鏃跺欐潵紜畾錛屽鍔犱簡紼嬪簭鐨勯氱敤鎬э紝鍍忔槸涓涓ā鏉褲傚懙鍛碉紝綾諱技C++鐨勬ā鏉匡紙綾諱技錛夈?/span>
1.1.1. 娉涘瀷閫氶厤絎?/font>
涓嬮潰鎴戜滑鍏堢湅鐪嬭繖浜涚▼搴忥細
//Code list 2
void TestGen0Medthod1(List l) {
for (Object o : l)
System.out.println(o);
}
鐪嬬湅榪欎釜鏂規硶鏈夋病鏈夊紓璁紝榪欎釜鏂規硶浼氶氳繃緙栬瘧鐨勶紝鍋囧浣犱紶鍏?/span>String錛屽氨鏄繖鏍?/span>List<String>銆傛帴鐫鎴戜滑璋冪敤瀹?/span>,闂灝卞嚭鐜頒簡錛屾垜浠皢涓涓?/span>List<String>褰撲綔List浼犵粰浜嗘柟娉曪紝JVM浼氱粰鎴戜滑涓涓鍛婏紝璇磋繖涓牬鍧忎簡綾誨瀷瀹夊叏錛屽洜涓轟粠List涓繑鍥炵殑閮芥槸Object綾誨瀷鐨勶紝鑰岃鎴戜滑鍐嶇湅鐪嬩笅闈㈢殑鏂規硶銆?/span>
//Code list 3
void TestGen0Medthod1(List<String> l) {
for (Object o : l)
System.out.println(o);
}
鍥犱負榪欓噷鐨?/span>List<String>涓嶆槸List<Object>鐨勫瓙綾?/span>,涓嶆槸String涓?/span>Object鐨勫叧緋伙紝灝辨槸璇?/span>List<String>涓嶉毝灞炰簬list<Object>,浠栦滑涓嶆槸緇ф壙鍏崇郴錛屾墍浠ユ槸涓嶈鐨勶紝榪欓噷鐨?/span>extends鏄〃紺洪檺鍒剁殑銆?/span>
綾誨瀷閫氶厤絎︽槸寰堢濂囩殑錛?/span>List<?>榪欎釜浣犺兘涓轟粬鍋氫粈涔堝憿?鎬庝箞閮芥槸“錛?#8221;錛屽畠浼間箮涓嶇‘瀹氾紝浠栨諱笉鑳借繑鍥炰竴涓紵浣滀負綾誨瀷鐨勬暟鎹惂錛屾槸鍟婁粬鏄笉浼氳繑鍥炰竴涓?#8220;錛?#8221;鏉ラ棶紼嬪簭鍛樼殑錛?/span>JVM浼氬仛綆鍗曠殑鎬濊冪殑錛岀湅鐪嬩唬鐮佸惂錛屾洿鐩磋浜涖?/span>
//code list 4
List<String> l1 = new ArrayList<String>();
li.add(“String”);
List<?> l2 = l1;
System.out.println(l1.get(0));
榪欐浠ｇ爜娌￠棶棰樼殑錛?/span>l1.get(0)灝嗚繑鍥炰竴涓?/span>Object銆?/span>
1.1.2. 緙栧啓娉涘瀷綾昏娉ㄦ剰錛?/font>
1銆?span style="font-family: Times New Roman; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> 鍦ㄥ畾涔変竴涓硾鍨嬬被鐨勬椂鍊欙紝鍦?/span> “<>”涔嬮棿瀹氫箟褰㈠紡綾誨瀷鍙傛暟錛屼緥濡傦細“class TestGen<K, V>”錛屽叾涓?#8220;K” , “V”涓嶄唬琛ㄥ鹼紝鑰屾槸琛ㄧず綾誨瀷銆?/span>
2銆?span style="font-family: Times New Roman; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> 瀹炰緥鍖栨硾鍨嬪璞＄殑鏃跺欙紝涓瀹氳鍦ㄧ被鍚嶅悗闈㈡寚瀹氱被鍨嬪弬鏁扮殑鍊鹼紙綾誨瀷錛夛紝涓鍏辮鏈変袱嬈′功鍐欍備緥濡傦細TestGen<String,String> t=new TestGen<String,String>()錛?/span>
3銆?span style="font-family: Times New Roman; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> 娉涘瀷涓?/span><K extends Object>,extends騫朵笉浠ｈ〃緇ф壙錛屽畠鏄被鍨嬭寖鍥撮檺鍒躲?/span>
1.2. 娉涘瀷涓庢暟鎹被鍨嬭漿鎹?/span>
1.2.1. 娑堥櫎綾誨瀷杞崲
涓婇潰鐨勪緥瀛愬ぇ瀹剁湅鍒頒粈涔堜簡錛屾暟鎹被鍨嬭漿鎹㈢殑浠ｇ爜涓嶈浜嗐傚湪浠ュ墠鎴戜滑緇忓父瑕佷功鍐欎互涓嬩唬鐮侊紝濡傦細
//code list 5
import java.util.Hashtable;
class Test {
public static void main(String[] args) {
Hashtable h = new Hashtable();
h.put("key", "value");
String s = (String)h.get("key");
System.out.println(s);
}
}
榪欎釜鎴戜滑鍋氫簡綾誨瀷杞崲錛屾槸涓嶆槸鎰熻寰堢儲鐨勶紝騫朵笖寮哄埗綾誨瀷杞崲浼氬甫鏉ユ綔鍦ㄧ殑鍗遍櫓錛岀郴緇熷彲鑳戒細鎶涗竴涓?/span>ClassCastException寮傚父淇℃伅銆傚湪JDK5.0涓垜浠畬鍏ㄥ彲浠ヨ繖涔堝仛錛屽錛?/span>
//code list 6
import java.util.Hashtable;
class Test {
public static void main(String[] args) {
Hashtable<String,Integer> h = new Hashtable<String,Integer> ();
h.put("key", new Integer(123));
int s = h.get("key").intValue();
System.out.println(s);
}
}
榪欓噷鎴戜滑浣跨敤娉涘寲鐗堟湰鐨?/span>HashMap,榪欐牱灝變笉鐢ㄦ垜浠潵緙栧啓綾誨瀷杞崲鐨勪唬鐮佷簡錛岀被鍨嬭漿鎹㈢殑榪囩▼浜ょ粰緙栬瘧鍣ㄦ潵澶勭悊錛屾槸涓嶆槸寰堟柟渚匡紝鑰屼笖寰堝畨鍏ㄣ備笂闈㈡槸String鏄犲皠鍒?/span>String錛屼篃鍙互灝?/span>Integer鏄犲皠涓?/span>String錛屽彧瑕佸啓鎴?/span>HashTable<Integer,String> h=new HashTable<Integer,String>();h.get(new Integer(0))榪斿洖value銆傛灉鐒跺緢鏂逛究銆?/span>
1.2.2. 鑷姩瑙ｅ寘瑁呬笌鑷姩鍖呰鐨勫姛鑳?/font>
浠庝笂闈㈡湁娌℃湁鐪嬪埌鏈夌偣鍒壄鍟婏紝h.get(new Integer(123))榪欓噷鐨?/span>new Integer(123);濂界儲鐨勶紝鍦?/span>JDK5.0涔嬪墠鎴戜滑鍙兘蹇嶇潃浜嗭紝鐜板湪榪欑闂宸茬粡瑙ｅ喅浜嗭紝璇風湅涓嬮潰榪欎釜鏂規硶銆傛垜浠紶鍏ヤ竴涓?/span>int榪欎竴鍩烘湰鍨嬪埆錛岀劧鍚庡啀灝?/span>i鐨勫肩洿鎺ユ坊鍔犲埌List涓紝鍏跺疄List鏄笉鑳藉偍瀛樺熀鏈瀷鍒殑錛?/span>List涓簲璇ュ瓨鍌ㄥ璞★紝榪欓噷緙栬瘧鍣ㄥ皢int鍖呰鎴?/span>Integer錛岀劧鍚庢坊鍔犲埌List涓幓銆傛帴鐫鎴戜滑鐢?/span>List.get(0);鏉ユ绱㈡暟鎹紝騫惰繑鍥炲璞″啀灝嗗璞¤В鍖呰鎴?/span>int銆傛仼錛?/span>JDK5.0緇欐垜浠甫鏉ユ洿澶氭柟渚夸笌瀹夊叏銆?/span>
//Code list 7
public void autoBoxingUnboxing(int i) {
ArrayList<Integer> L= new ArrayList<Integer>();
L.add(i);
int a = L.get(0);
System.out.println("The value of i is " + a);
}
1.2.3. 闄愬埗娉涘瀷涓被鍨嬪弬鏁扮殑鑼冨洿
涔熻浣犲凡緇忓彂鐜板湪code list 1涓殑TestGen<K,V>榪欎釜娉涘瀷綾?/span>,鍏朵腑K,V鍙互鏄換鎰忕殑鍨嬪埆銆備篃璁鎬綘鏈夋椂鍊欏憿鎯抽檺瀹氫竴涓?/span>K鍜?/span>V褰撶劧鑼冨洿錛屾庝箞鍋氬憿錛熺湅鐪嬪涓嬬殑浠ｇ爜錛?/span>
//Code list 8
class TestGen2<K extents String,V extends Number>
{
private V v=null;
private K k=null;
public void setV(V v){
this.v=v;
}
public V getV(){
return this.v;
}
public void setK(K k){
this.k=k;
}
public V getK(){
return this.k;
}
public static void main(String[] args)
{
TestGen2<String,Integer> t2=new TestGen2<String,Integer>();
t2.setK(new String("String"));
t2.setV(new Integer(123));
System.out.println(t2.getK());
System.out.println(t2.getV());
}
}
]]>