发表于 2009-1-5 19:48
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Java鏄紶鍊艰繕鏄紶寮曠敤
鍙戝竷: 2008-12-02 17:56 | 浣滆: webmaster | 鏉ユ簮: 鏈珯鍘熷垱 | 鏌ョ湅: 4娆
銆銆Java 鏂规硶鐨勫弬鏁版槸绠鍗曠被鍨嬬殑鏃跺欙紝鏄寜鍊间紶閫掔殑 (pass by value)銆傝繖涓鐐规垜浠彲浠ラ氳繃涓涓畝鍗曠殑渚嬪瓙鏉ヨ鏄庯細
/* 渚 1 */
/**
* @(#) Test.java
* @author fancy
*/
public class Test {
public static void test(boolean test) {
test = ! test;
System.out.println("In test(boolean) : test = " test);
}
public static void main(String[] args) {
boolean test = true;
System.out.println("Before test(boolean) : test = " test);
test(test);
System.out.println("After test(boolean) : test = " test);
}
}
銆銆杩愯缁撴灉锛
Before test(boolean) : test = true
In test(boolean) : test = false
After test(boolean) : test = true
銆銆涓嶉毦鐪嬪嚭锛岃櫧鐒跺湪 test(boolean) 鏂规硶涓敼鍙樹簡浼犺繘鏉ョ殑鍙傛暟鐨勫硷紝浣嗗杩欎釜鍙傛暟婧愬彉閲忔湰韬苟娌℃湁褰卞搷锛屽嵆瀵 main(String[]) 鏂规硶閲岀殑 test 鍙橀噺娌℃湁褰卞搷銆傞偅璇存槑锛屽弬鏁扮被鍨嬫槸绠鍗曠被鍨嬬殑鏃跺欙紝鏄寜鍊间紶閫掔殑銆備互鍙傛暟褰㈠紡浼犻掔畝鍗曠被鍨嬬殑鍙橀噺鏃讹紝瀹為檯涓婃槸灏嗗弬鏁扮殑鍊间綔浜嗕竴涓嫹璐濅紶杩涙柟娉曞嚱鏁扮殑锛岄偅涔堝湪鏂规硶鍑芥暟閲屽啀鎬庝箞鏀瑰彉鍏跺硷紝鍏剁粨鏋滈兘鏄彧鏀瑰彉浜嗘嫹璐濈殑鍊硷紝鑰屼笉鏄簮鍊笺
銆銆2. 浠涔堟槸寮曠敤
銆銆Java 鏄紶鍊艰繕鏄紶寮曠敤锛岄棶棰樹富瑕佸嚭鍦ㄥ璞＄殑浼犻掍笂锛屽洜涓 Java 涓畝鍗曠被鍨嬫病鏈夊紩鐢ㄣ傛棦鐒朵簤璁轰腑鎻愬埌浜嗗紩鐢ㄨ繖涓笢瑗匡紝涓轰簡鎼炴竻妤氳繖涓棶棰橈紝鎴戜滑蹇呴』瑕佺煡閬撳紩鐢ㄦ槸浠涔堛
銆銆绠鍗曠殑璇达紝寮曠敤鍏跺疄灏卞儚鏄竴涓璞＄殑鍚嶅瓧鎴栬呭埆鍚 (alias)锛屼竴涓璞″湪鍐呭瓨涓細璇锋眰涓鍧楃┖闂存潵淇濆瓨鏁版嵁锛屾牴鎹璞＄殑澶у皬锛屽畠鍙兘闇瑕佸崰鐢ㄧ殑绌洪棿澶у皬涔熶笉绛夈傝闂璞＄殑鏃跺欙紝鎴戜滑涓嶄細鐩存帴鏄闂璞″湪鍐呭瓨涓殑鏁版嵁锛岃屾槸閫氳繃寮曠敤鍘昏闂傚紩鐢ㄤ篃鏄竴绉嶆暟鎹被鍨嬶紝鎴戜滑鍙互鎶婂畠鎯宠薄涓虹被浼 C 璇█涓寚閽堢殑涓滆タ锛屽畠鎸囩ず浜嗗璞″湪鍐呭瓨涓殑鍦板潃鈥斺斿彧涓嶈繃鎴戜滑涓嶈兘澶熻瀵熷埌杩欎釜鍦板潃绌剁珶鏄粈涔堛
銆銆濡傛灉鎴戜滑瀹氫箟浜嗕笉姝竴涓紩鐢ㄦ寚鍚戝悓涓涓璞★紝閭ｄ箞杩欎簺寮曠敤鏄笉鐩稿悓鐨勶紝鍥犱负寮曠敤涔熸槸涓绉嶆暟鎹被鍨嬶紝闇瑕佷竴瀹氱殑鍐呭瓨绌洪棿鏉ヤ繚瀛樸備絾鏄畠浠殑鍊兼槸鐩稿悓鐨勶紝閮芥寚绀哄悓涓涓璞″湪鍐呭瓨鐨勪腑浣嶇疆銆傛瘮濡
String a = "Hello";
String b = a;
銆銆杩欓噷锛宎 鍜 b 鏄笉鍚岀殑涓や釜寮曠敤锛屾垜浠娇鐢ㄤ簡涓や釜瀹氫箟璇彞鏉ュ畾涔夊畠浠備絾瀹冧滑鐨勫兼槸涓鏍风殑锛岄兘鎸囧悜鍚屼竴涓璞 "Hello"銆備篃璁镐綘杩樿寰椾笉澶熺洿瑙傦紝鍥犱负 String 瀵硅薄鐨勫兼湰韬槸涓嶅彲鏇存敼鐨 (鍍 b = "World"; b = a; 杩欑鎯呭喌涓嶆槸鏀瑰彉浜 "World" 杩欎竴瀵硅薄鐨勫硷紝鑰屾槸鏀瑰彉浜嗗畠鐨勫紩鐢 b 鐨勫间娇涔嬫寚鍚戜簡鍙︿竴涓 String 瀵硅薄 a)銆傞偅涔堟垜浠敤 StringBuffer 鏉ヤ妇涓涓緥瀛愶細
/* 渚 2 */
/**
* @(#) Test.java
* @author fancy
*/
public class Test {
public static void main(String[] args) {
StringBuffer a = new StringBuffer("Hello");
StringBuffer b = a;
b.append(", World");
System.out.println("a is " a);
}
}
銆銆杩愯缁撴灉锛
a is Hello, World
銆銆杩欎釜渚嬪瓙涓 a 鍜 b 閮芥槸寮曠敤锛屽綋鏀瑰彉浜 b 鎸囩ず鐨勫璞＄殑鍊肩殑鏃跺欙紝浠庤緭鍑虹粨鏋滄潵鐪嬶紝a 鎵鎸囩ず鐨勫璞＄殑鍊间篃鏀瑰彉浜嗐傛墍浠ワ紝a 鍜 b 閮芥寚鍚戝悓涓涓璞″嵆鍖呭惈 "Hello" 鐨勪竴涓 StringBuffer 瀵硅薄銆
銆銆杩欓噷鎴戞弿杩颁簡涓や釜瑕佺偣锛
1. 寮曠敤鏄竴绉嶆暟鎹被鍨嬶紝淇濆瓨浜嗗璞″湪鍐呭瓨涓殑鍦板潃锛岃繖绉嶇被鍨嬪嵆涓嶆槸鎴戜滑骞虫椂鎵璇寸殑绠鍗曟暟鎹被鍨嬩篃涓嶆槸绫诲疄渚(瀵硅薄)锛
2. 涓嶅悓鐨勫紩鐢ㄥ彲鑳芥寚鍚戝悓涓涓璞★紝鎹㈠彞璇濊锛屼竴涓璞″彲浠ユ湁澶氫釜寮曠敤锛屽嵆璇ョ被绫诲瀷鐨勫彉閲忋
銆銆3. 瀵硅薄鏄浣曚紶閫掔殑鍛
銆銆鍏充簬瀵硅薄鐨勪紶閫掞紝鏈変袱绉嶈娉曪紝鍗斥滃畠鏄寜鍊间紶閫掔殑鈥濆拰鈥滃畠鏄寜寮曠敤浼犻掔殑鈥濄傝繖涓ょ璇存硶鍚勬湁鍚勭殑閬撶悊锛屼絾鏄畠浠兘娌℃湁浠庢湰璐ㄤ笂鍘诲垎鏋愶紝鍗宠嚧浜庝骇鐢熶簡浜夎銆
銆銆鏃㈢劧鐜板湪鎴戜滑宸茬粡鐭ラ亾浜嗗紩鐢ㄦ槸浠涔堜笢瑗匡紝閭ｄ箞鐜板湪涓嶅Θ鏉ュ垎鏋愪竴涓嬪璞′綔鏄弬鏁版槸濡備綍浼犻掔殑銆傝繕鏄厛浠ヤ竴涓▼搴忎负渚嬶細
/* 渚 3 */
/**
* @(#) Test.java
* @author fancy
*/
public class Test {
public static void test(StringBuffer str) {
str.append(", World!");
}
public static void main(String[] args) {
StringBuffer string = new StringBuffer("Hello");
test(string);
System.out.println(string);
}
}
銆銆杩愯缁撴灉锛
銆銆Hello, World!
銆銆test(string) 璋冪敤浜 test(StringBuffer) 鏂规硶锛屽苟灏 string 浣滀负鍙傛暟浼犻掍簡杩涘幓銆傝繖閲 string 鏄竴涓紩鐢紝杩欎竴鐐规槸鍕垮焊缃枒鐨勩傚墠闈㈡彁鍒帮紝寮曠敤鏄竴绉嶆暟鎹被鍨嬶紝鑰屼笖涓嶆槸瀵硅薄锛屾墍浠ュ畠涓嶅彲鑳芥寜寮曠敤浼犻掞紝鎵浠ュ畠鏄寜鍊间紶閫掔殑锛屽畠涔堝畠鐨勫肩┒绔熸槸浠涔堝憿锛熸槸瀵硅薄鐨勫湴鍧銆
銆銆鐢辨鍙锛屽璞′綔涓哄弬鏁扮殑鏃跺欐槸鎸夊间紶閫掔殑锛屽鍚楋紵閿欙紒涓轰粈涔堥敊锛岃鎴戜滑鐪嬪彟涓涓緥瀛愶細
/* 渚 4 */
/**
* @(#) Test.java
* @author fancy
*/
public class Test {
public static void test(String str) {
str = "World";
}
public static void main(String[] args) {
String string = "Hello";
test(string);
System.out.println(string);
}
}
銆銆杩愯缁撴灉锛
Hello
銆銆涓轰粈涔堜細杩欐牱鍛紵鍥犱负鍙傛暟 str 鏄竴涓紩鐢紝鑰屼笖瀹冧笌 string 鏄笉鍚岀殑寮曠敤锛岃櫧鐒跺畠浠兘鏄悓涓涓璞＄殑寮曠敤銆俿tr = "World" 鍒欐敼鍙樹簡 str 鐨勫硷紝浣夸箣鎸囧悜浜嗗彟涓涓璞★紝鐒惰 str 鎸囧悜鐨勫璞℃敼鍙樹簡锛屼絾瀹冨苟娌℃湁瀵 "Hello" 閫犳垚浠讳綍褰卞搷锛岃屼笖鐢变簬 string 鍜 str 鏄笉鍚岀殑寮曠敤锛宻tr 鐨勬敼鍙樹篃娌℃湁瀵 string 閫犳垚浠讳綍褰卞搷锛岀粨鏋滃氨濡備緥涓墍绀恒
銆銆鍏剁粨鏋滄槸鎺ㄧ炕浜嗗弬鏁版寜鍊间紶閫掔殑璇存硶銆傞偅涔堬紝瀵硅薄浣滀负鍙傛暟鐨勬椂鍊欐槸鎸夊紩鐢ㄤ紶閫掔殑浜嗭紵涔熼敊锛佸洜涓轰笂涓涓緥瀛愮殑纭兘澶熻鏄庡畠鏄寜鍊间紶閫掔殑銆
銆銆缁撴灉锛屽氨鍍忓厜鍒板簳鏄尝杩樻槸绮掑瓙鐨勯棶棰樹竴鏍凤紝Java 鏂规硶鐨勫弬鏁版槸鎸変粈涔堜紶閫掔殑闂锛屽叾绛旀灏卞彧鑳芥槸锛氬嵆鏄寜鍊间紶閫掍篃鏄寜寮曠敤浼犻掞紝鍙槸鍙傜収鐗╀笉鍚岋紝缁撴灉涔熷氨涓嶅悓銆
銆銆4. 姝ｇ‘鐪嬪緟浼犲艰繕鏄紶寮曠敤鐨勯棶棰
銆銆瑕佹纭殑鐪嬪緟杩欎釜闂蹇呴』瑕佹悶娓呮涓轰粈涔堜細鏈夎繖鏍蜂竴涓棶棰樸
銆銆瀹為檯涓婏紝闂鏉ユ簮浜 C锛岃屼笉鏄 Java銆
銆銆C 璇█涓湁涓绉嶆暟鎹被鍨嬪彨鍋氭寚閽堬紝浜庢槸灏嗕竴涓暟鎹綔涓哄弬鏁颁紶閫掔粰鏌愪釜鍑芥暟鐨勬椂鍊欙紝灏辨湁涓ょ鏂瑰紡锛氫紶鍊硷紝鎴栨槸浼犳寚閽堬紝瀹冧滑鐨勫尯鍒紝鍙互鐢ㄤ竴涓畝鍗曠殑渚嬪瓙璇存槑锛
/* 渚 5 */
/**
* @(#) test.c
* @author fancy
*/
void SwapValue(int a, int b) {
int t = a;
a = b;
b = t;
}
void SwapPointer(int * a, int * b) {
int t = * a;
* a = * b;
* b = t;
}
void main() {
int a = 0, b = 1;
printf("1 : a = %d, b = %d\n", a, b);
SwapValue(a, b);
printf("2 : a = %d, b = %d\n", a, b);
SwapPointer(&a, &b);
printf("3 : a = %d, b = %d\n", a, b);
}
銆銆杩愯缁撴灉锛
1 : a = 0, b = 1
2 : a = 0, b = 1
3 : a = 1, b = 0
銆銆澶у鍙互鏄庢樉鐨勭湅鍒帮紝鎸夋寚閽堜紶閫掑弬鏁板彲浠ユ柟渚跨殑淇敼閫氳繃鍙傛暟浼犻掕繘鏉ョ殑鍊硷紝鑰屾寜鍊间紶閫掑氨涓嶈銆
銆銆褰 Java 鎴愰暱璧锋潵鐨勬椂鍊欙紝璁稿鐨 C 绋嬪簭鍛樺紑濮嬭浆鍚戝涔 Java锛屼粬浠彂鐜帮紝浣跨敤绫讳技 SwapValue 鐨勬柟娉曚粛鐒朵笉鑳芥敼鍙橀氳繃鍙傛暟浼犻掕繘鏉ョ殑绠鍗曟暟鎹被鍨嬬殑鍊硷紝浣嗘槸濡傛灉鏄竴涓璞★紝鍒欏彲鑳藉皢鍏舵垚鍛橀殢鎰忔洿鏀广備簬鏄粬浠寰楄繖寰堝儚鏄 C 璇█涓紶鍊/浼犳寚閽堢殑闂銆備絾鏄 Java 涓病鏈夋寚閽堬紝閭ｄ箞杩欎釜闂灏辨紨鍙樻垚浜嗕紶鍊/浼犲紩鐢ㄧ殑闂銆傚彲鎯滃皢杩欎釜闂鏀惧湪 Java 涓繘琛岃璁哄苟涓嶆伆褰撱
銆銆璁ㄨ杩欐牱涓涓棶棰樼殑鏈缁堢洰鐨勫彧鏄负浜嗘悶娓呮浣曠鎯呭喌鎵嶈兘鍦ㄦ柟娉曞嚱鏁颁腑鏂逛究鐨勬洿鏀瑰弬鏁扮殑鍊煎苟浣夸箣闀挎湡鏈夋晥銆
銆銆Java 涓紝鏀瑰彉鍙傛暟鐨勫兼湁涓ょ鎯呭喌锛岀涓绉嶏紝浣跨敤璧嬪煎彿鈥=鈥濈洿鎺ヨ繘琛岃祴鍊间娇鍏舵敼鍙橈紝濡備緥 1 鍜屼緥 4锛涚浜岀锛屽浜庢煇浜涘璞＄殑寮曠敤锛岄氳繃涓瀹氶斿緞瀵瑰叾鎴愬憳鏁版嵁杩涜鏀瑰彉锛屽渚 3銆傚浜庣涓绉嶆儏鍐碉紝鍏舵敼鍙樹笉浼氬奖鍝嶅埌鏂规硶璇ユ柟娉曚互澶栫殑鏁版嵁锛屾垨鑰呯洿鎺ヨ婧愭暟鎹傝岀浜岀鏂规硶锛屽垯鐩稿弽锛屼細褰卞搷鍒版簮鏁版嵁鈥斺斿洜涓哄紩鐢ㄦ寚绀虹殑瀵硅薄娌℃湁鍙橈紝瀵瑰叾鎴愬憳鏁版嵁杩涜鏀瑰彉鍒欏疄璐ㄤ笂鏄敼鍙樼殑璇ュ璞°
銆銆5. 濡備綍瀹炵幇绫讳技 swap 鐨勬柟娉
銆銆浼犲艰繕鏄紶寮曠敤鐨勯棶棰橈紝鍒版宸茬粡绠楁槸瑙ｅ喅浜嗭紝浣嗘槸鎴戜滑浠嶇劧涓嶈兘瑙ｅ喅杩欐牱涓涓棶棰橈細濡傛灉鎴戞湁涓や釜 int 鍨嬬殑鍙橀噺 a 鍜 b锛屾垜鎯冲啓涓涓柟娉曟潵浜ゆ崲瀹冧滑鐨勫硷紝搴旇鎬庝箞鍔烇紵
銆銆缁撹寰堣浜哄け鏈涒斺旀病鏈夊姙娉曪紒鍥犳锛屾垜浠彧鑳藉叿浣撴儏鍐靛叿浣撹璁猴紝浠ョ粡甯镐娇鐢ㄤ氦鎹㈡柟娉曠殑鎺掑簭涓轰緥锛
/** 渚 6 */
/**
* @(#) Test.java
* @author fancy
*/
public class Test {
public static void swap(int[] data, int a, int b) {
int t = data[a];
data[a] = data[b];
data[b] = t;
}
public static void main(String[] args) {
int[] data = new int[10];
for (int i = 0; i < 10; i ) {
data[i] = (int) (Math.random() * 100);
System.out.print(" " data[i]);
}
System.out.println();
for (int i = 0; i < 9; i ) {
for (int j = i; j < 10; j ) {
if (data[i] > data[j]) {
swap(data, i, j);
}
}
}
for (int i = 0; i < 10; i ) {
System.out.print(" " data[i]);
}
System.out.println();
}
}
銆銆杩愯缁撴灉(鎯呭喌涔嬩竴)锛
78 69 94 38 95 31 50 97 84 1
1 31 38 50 69 78 84 94 95 97
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