]]>
]]>
銆銆 Java姒傝堪:
銆銆 鐩墠Java涓昏搴旂敤浜庝腑闂翠歡鐨勫紑鍙?middleware)---澶勭悊瀹㈡埛鏈轟簬鏈嶅姟鍣ㄤ箣闂寸殑閫氫俊鎶鏈?鏃╂湡鐨勫疄璺佃瘉鏄?Java涓嶉傚悎pc搴旂敤紼嬪簭鐨勫紑鍙?鍏跺彂灞曢愭笎鍙樻垚鍦ㄥ紑鍙戞墜鎸佽澶?浜掕仈緗戜俊鎭珯,鍙婅濺杞借綆楁満鐨勫紑鍙?Java浜庡叾浠栬璦鎵涓嶅悓鐨勬槸紼嬪簭榪愯鏃舵彁渚涗簡騫沖彴鐨勭嫭绔嬫?縐拌鍙互鍦╳indows,solaris,linux鍏朵粬鎿嶄綔緋葷粺涓婁嬌鐢ㄥ畬鍏ㄧ浉鍚岀殑浠ｇ爜.Java鐨勮娉曚笌C++璇硶綾諱技,C++/C紼嬪簭鍛樺緢瀹規槗鎺屾彙,鑰屼笖Java鏄畬鍏ㄧ殑褰誨簳鐨勯潰鍚戝璞＄殑,鍏朵腑鎻愬嚭浜嗗緢濂界殑GC(Garbage Collector)鍨冨溇澶勭悊鏈哄埗,闃叉鍐呭瓨婧㈠嚭.
銆銆 Java鐨勭櫧鐨功涓烘垜浠彁鍑轟簡Java璇█鐨?1涓叧閿壒鎬?
銆銆 (1)Easy:Java鐨勮娉曟瘮C++鐨勭浉瀵圭畝鍗?鍙︿竴涓柟闈㈠氨鏄疛ava鑳戒嬌杞歡鍦ㄥ緢灝忕殑鏈哄櫒涓婅繍琛?鍩虹瑙ｉ噴鍏跺拰綾誨簱鐨勬敮鎸佺殑澶у皬綰︿負40kb,澧炲姞鍩烘湰鐨勬爣鍑嗗簱鍜岀嚎紼嬫敮鎸佺殑鍐呭瓨闇瑕佸鍔?25kb.
銆銆 (2)鍒嗗竷寮?Java甯︽湁寰堝己澶х殑TCP/IP鍗忚鏃忕殑渚嬬▼搴?Java搴旂敤紼嬪簭鑳藉閫氳繃URL鏉ョ┛榪囩綉緇滄潵璁塊棶榪滅▼瀵硅薄,鐢變簬servlet鏈哄埗鐨勫嚭鐜?浣縅ava緙栫▼闈炲父鐨勯珮鏁?鐜板湪璁稿鐨勫ぇ鐨剋eb server閮芥敮鎸乻ervlet.
銆銆 (3)OO:闈㈠悜瀵硅薄璁捐鏄妸閲嶇偣鏀懼湪瀵硅薄鍙婂璞＄殑鎺ュ彛涓婄殑涓涓紪紼嬫妧鏈?鍏墮潰鍚戝璞″拰C++鏈夊緢澶氫笉鍚?鍦ㄤ笌澶氶噸緇ф壙鐨勫鐞嗗強Java鐨勫師綾繪ā鍨?
銆銆 (4)鍋ュ．鐗規?Java閲囧彇浜嗕竴涓畨鍏ㄦ寚閽堟ā鍨?鑳藉噺灝忛噸鍐欏唴瀛樺拰鏁版嵁宕╂簝鐨勫彲鑳芥с?
銆銆 (5)瀹夊叏:Java鐢ㄦ潵璁捐緗戣礬鍜屽垎甯冪郴緇?榪欏甫鏉ヤ簡鏂扮殑瀹夊叏闂,Java鍙互鐢ㄦ潵鏋勫緩闃茬梾姣掑拰闃叉敾鍑葷殑System.浜嬪疄璇佹槑Java鍦ㄩ槻姣掕繖涓鏂歸潰鍋氱殑姣旇緝濂?
銆銆 (6)涓珛浣撶郴緇撴瀯:Java緙栬瘧鍏剁敓鎴愪綋緋葷粨鏋勪腑绔嬬殑鐩爣鏂囦歡鏍煎紡鍙互鍦ㄥ緢澶氬鐞嗗櫒涓婃墽琛?緙栬瘧鍣ㄤ駭鐢熺殑鎸囦護瀛楄妭鐮?Javabytecode)瀹炵幇姝ょ壒鎬?姝ゅ瓧鑺傜爜鍙互鍦ㄤ換浣曟満鍣ㄤ笂瑙ｉ噴鎵ц.
銆銆 (7)鍙Щ妞嶆?Java涓鍩烘湰鏁版嵁緇撴瀯綾誨瀷鐨勫ぇ灝忓拰綆楁硶閮芥湁涓ユ牸鐨勮瀹氭墍浠ュ彲縐繪鎬у緢濂?
銆銆 (8)澶氱嚎紼?Java澶勭悊澶氱嚎紼嬬殑榪囩▼寰堢畝鍗?Java鎶婂綰跨▼瀹炵幇浜ょ粰搴曚笅鎿嶄綔緋葷粺鎴栫嚎紼嬬▼搴忓畬鎴?鎵浠ュ綰跨▼鏄疛ava浣滀負鏈嶅姟鍣ㄧ寮鍙戣璦鐨勬祦琛屽師鍥犱箣涓
銆銆 (9)Applet鍜宻ervlet:鑳藉鍦ㄧ綉欏典笂鎵ц鐨勭▼搴忓彨Applet,闇瑕佹敮鎸丣ava鐨勬祻瑙堝櫒寰堝,鑰宎pplet鏀寔鍔ㄦ佺殑緗戦〉,榪欐槸寰堝鍏朵粬璇█鎵涓嶈兘鍋氬埌鐨?
銆銆 鍩烘湰姒傚康:
銆銆 1.OOP涓敮涓鍏崇郴鐨勬槸瀵硅薄鐨勬帴鍙ｆ槸浠涔?灝卞儚璁＄畻鏈虹殑閿鍞晢濂逛笉綆＄數婧愬唴閮ㄧ粨鏋勬槸鎬庢牱鐨?浠栧彧鍏崇郴鑳藉惁緇欎綘鎻愪緵鐢靛氨琛屼簡,涔熷氨鏄彧瑕佺煡閬揷an or not鑰屼笉鏄痟ow and why.鎵鏈夌殑紼嬪簭鏄敱涓瀹氱殑灞炴у拰琛屼負瀵硅薄緇勬垚鐨?涓嶅悓鐨勫璞＄殑璁塊棶閫氳繃鍑芥暟璋冪敤鏉ュ畬鎴?瀵硅薄闂存墍鏈夌殑浜ゆ祦閮芥槸閫氳繃鏂規硶璋冪敤,閫氳繃瀵瑰皝瑁呭璞℃暟鎹?寰堝ぇ闄愬害涓婃彁楂樺鐢ㄧ巼.
銆銆 2.OOP涓渶閲嶈鐨勬濇兂鏄被,綾繪槸妯℃澘鏄摑鍥?浠庣被涓瀯閫犱竴涓璞?鍗沖垱寤轟簡榪欎釜綾葷殑涓涓疄渚?instance)
銆銆 3.灝佽:灝辨槸鎶婃暟鎹拰琛屼負緇撳悎璧峰湪涓涓寘涓?騫跺瀵硅薄浣跨敤鑰呴殣钘忔暟鎹殑瀹炵幇榪囩▼,涓涓璞′腑鐨勬暟鎹彨浠栫殑瀹炰緥瀛楁(instance field)
銆銆 4.閫氳繃鎵╁睍涓涓被鏉ヨ幏寰椾竴涓柊綾誨彨緇ф壙(inheritance),鑰屾墍鏈夌殑綾婚兘鏄敱Object鏍硅秴綾繪墿灞曡屽緱,鏍硅秴綾諱笅鏂囦細鍋氫粙緇?
銆銆 5.瀵硅薄鐨?涓富瑕佺壒鎬?
銆銆 behavior---璇存槑榪欎釜瀵硅薄鑳藉仛浠涔?
銆銆 state---褰撳璞℃柦鍔犳柟娉曟椂瀵硅薄鐨勫弽鏄?
銆銆 identity---涓庡叾浠栫浉浼艱涓哄璞＄殑鍖哄垎鏍囧織.
銆銆 姣忎釜瀵硅薄鏈夊敮涓鐨刬ndentity 鑰岃繖3鑰呬箣闂寸浉浜掑獎鍝?
銆銆 6.綾諱箣闂寸殑鍏崇郴:
銆銆 use-a :渚濊禆鍏崇郴
銆銆 has-a :鑱氬悎鍏崇郴
銆銆 is-a :緇ф壙鍏崇郴--渚?A綾葷戶鎵夸簡B綾?姝ゆ椂A綾諱笉浠呮湁浜咮綾葷殑鏂規硶,榪樻湁鍏惰嚜宸辯殑鏂規硶.(涓у瓨鍦ㄤ簬鍏辨т腑)
銆銆 7.鏋勯犲璞′嬌鐢ㄦ瀯閫犲櫒:鏋勯犲櫒鐨勬彁鍑?鏋勯犲櫒鏄竴縐嶇壒孌婄殑鏂規硶,鏋勯犲璞″茍瀵瑰叾鍒濆鍖?
銆銆 渚?Data綾葷殑鏋勯犲櫒鍙獶ata
銆銆 new Data()---鏋勯犱竴涓柊瀵硅薄,涓斿垵濮嬪寲褰撳墠鏃墮棿.
銆銆 Data happyday=new
銆銆 Data()---鎶婁竴涓璞¤祴鍊肩粰涓涓彉閲廻appyday,浠庤屼嬌璇ュ璞¤兘澶熷嬈′嬌鐢?姝ゅ瑕佸０鏄庣殑浣垮彉閲忎笌瀵硅薄鍙橀噺浜岃呮槸涓嶅悓鐨?new榪斿洖鐨勫兼槸涓涓紩鐢?
銆銆 鏋勯犲櫒鐗圭偣:鏋勯犲櫒鍙互鏈?涓?涓涓垨澶氫釜鍙傛暟
銆銆 鏋勯犲櫒鍜岀被鏈夌浉鍚岀殑鍚嶅瓧
銆銆 涓涓被鍙互鏈夊涓瀯閫犲櫒
銆銆 鏋勯犲櫒娌℃湁榪斿洖鍊?
銆銆 鏋勯犲櫒鎬繪槸鍜宯ew榪愮畻絎︿竴璧蜂嬌鐢?
銆銆 8.閲嶈澆:褰撳涓柟娉曞叿鏈夌浉鍚岀殑鍚嶅瓧鑰屽惈鏈変笉鍚岀殑鍙傛暟鏃?渚垮彂鐢熼噸杞?緙栬瘧鍣ㄥ繀欏繪寫閫夊嚭璋冪敤鍝釜鏂規硶.
銆銆 9.鍖?package)Java鍏佽鎶婁竴涓垨澶氫釜綾繪敹闆嗗湪涓璧鋒垚涓轟竴緇?縐頒綔鍖?浠ヤ究浜庣粍緇囦換鍔?鏍囧噯Java搴撳垎涓鴻澶氬寘.java.lang java.util java,net絳?鍖呮槸鍒嗗眰嬈＄殑鎵鏈夌殑java鍖呴兘鍦╦ava鍜宩avax鍖呭眰嬈″唴.
銆銆 10.緇ф壙鎬濇兂:鍏佽鍦ㄥ凡緇忓瓨鍦ㄧ殑綾葷殑鍩虹涓婃瀯寤烘柊鐨勭被,褰撲綘緇ф壙涓涓凡緇忓瓨鍦ㄧ殑綾繪椂,閭ｄ箞浣犲氨澶嶇敤浜嗚繖涓被鐨勬柟娉曞拰瀛楁,鍚屾椂浣犲彲浠ュ湪鏂扮被涓坊鍔犳柊鐨勬柟娉曞拰瀛楁.
銆銆 11.鎵╁睍綾?鎵╁睍綾誨厖鍒嗕綋鐜頒簡is-a鐨勭戶鎵垮叧緋? 褰㈠紡涓?class (瀛愮被) extends (鍩虹被).
銆銆 12.澶氭?鍦╦ava涓?瀵硅薄鍙橀噺鏄鎬佺殑.鑰宩ava涓笉鏀寔澶氶噸緇ф壙.
銆銆 13.鍔ㄦ佺粦瀹?璋冪敤瀵硅薄鏂規硶鐨勬満鍒?
銆銆 (1)緙栬瘧鍣ㄦ鏌ュ璞″０鏄庣殑綾誨瀷鍜屾柟娉曞悕.
銆銆 (2)緙栬瘧鍣ㄦ鏌ユ柟娉曡皟鐢ㄧ殑鍙傛暟綾誨瀷.
銆銆 (3)闈欐佺粦瀹?鑻ユ柟娉曠被鍨嬩負priavte static final 緙栬瘧鍣ㄤ細鍑嗙‘鐭ラ亾璇ヨ皟鐢ㄥ摢涓柟娉?
銆銆 (4)褰撶▼搴忚繍琛屽茍涓斾嬌鐢ㄥ姩鎬佺粦瀹氭潵璋冪敤涓涓柟娉曟椂,閭ｄ箞铏氭嫙鏈哄繀欏昏皟鐢▁鎵鎸囧悜鐨勫璞＄殑瀹為檯綾誨瀷鐩稿尮閰嶇殑鏂規硶鐗堟湰.
銆銆 (5)鍔ㄦ佺粦瀹?鏄緢閲嶈鐨勭壒鎬?瀹冭兘浣跨▼搴忓彉寰楀彲鎵╁睍鑰屼笉闇瑕侀噸緙栬瘧宸插瓨浠ｇ爜.
銆銆 14.final綾?涓洪槻姝粬浜轟粠浣犵殑綾諱笂媧劇敓鏂扮被,姝ょ被鏄笉鍙墿灞曠殑.
銆銆 15.鍔ㄦ佽皟鐢ㄦ瘮闈欐佽皟鐢ㄨ姳璐圭殑鏃墮棿瑕侀暱,
銆銆 16.鎶借薄綾?瑙勫畾涓涓垨澶氫釜鎶借薄鏂規硶鐨勭被鏈韓蹇呴』瀹氫箟涓篴bstract渚? public abstract string getDescripition
銆銆 17.Java涓殑姣忎竴涓被閮芥槸浠嶰bject綾繪墿灞曡屾潵鐨?
銆銆 18.object綾諱腑鐨別qual鍜宼oString鏂規硶.equal鐢ㄤ簬嫻嬭瘯涓涓璞℃槸鍚﹀悓鍙︿竴涓璞＄浉絳?toString榪斿洖涓涓唬琛ㄨ瀵硅薄鐨勫瓧絎︿覆,鍑犱箮姣忎竴涓被閮戒細閲嶈澆璇ユ柟娉?浠ヤ究榪斿洖褰撳墠鐘舵佺殑姝ｇ‘琛ㄧず.(toString 鏂規硶鏄竴涓緢閲嶈鐨勬柟娉?
銆銆 19.閫氱敤緙栫▼:浠諱綍綾葷被鍨嬬殑鎵鏈夊奸兘鍙互鍚宱bject綾繪х殑鍙橀噺鏉ヤ唬鏇?
銆銆 20.鏁扮粍鍒楄〃:ArrayList鍔ㄦ佹暟緇勫垪琛?鏄竴涓被搴?瀹氫箟鍦╦ava.uitl鍖呬腑,鍙嚜鍔ㄨ皟鑺傛暟緇勭殑澶у皬.
銆銆 21.class綾?object綾諱腑鐨刧etclass鏂規硶榪斿洖ckass綾誨瀷鐨勪竴涓疄渚?紼嬪簭鍚姩鏃跺寘鍚湪main鏂規硶鐨勭被浼氳鍔犺澆,铏氭嫙鏈鴻鍔犺澆浠栭渶瑕佺殑鎵鏈夌被,姣忎竴涓姞杞界殑綾婚兘瑕佸姞杞藉畠闇瑕佺殑綾?
銆銆 22.class綾諱負緙栧啓鍙姩鎬佹搷綰礿ava浠ｇ爜鐨勭▼搴忔彁渚涗簡寮哄ぇ鐨勫姛鑳藉弽灝?榪欓」鍔熻兘涓篔avaBeans鐗瑰埆鏈夌敤,浣跨敤鍙嶅皠Java鑳芥敮鎸乂B紼嬪簭鍛樹範鎯嬌鐢ㄧ殑宸ュ叿.鑳藉鍒嗘瀽綾昏兘鍔涚殑紼嬪簭鍙弽灝勫櫒,Java涓彁渚涙鍔熻兘鐨勫寘鍙獼ava.lang.reflect鍙嶅皠鏈哄埗鍗佸垎寮哄ぇ.
銆銆 1.鍦ㄨ繍琛屾椂鍒嗘瀽綾葷殑鑳藉姏.
銆銆 2.鍦ㄨ繍琛屾椂鎺㈠療綾葷殑瀵硅薄.
銆銆 3.瀹炵幇閫氱敤鏁扮粍鎿嶇旱浠ｇ爜.
銆銆 4.鎻愪緵鏂規硶瀵硅薄.
銆銆 鑰屾鏈哄埗涓昏閽堝鏄伐鍏瘋呰屼笉鏄簲鐢ㄥ強紼嬪簭.
銆銆 鍙嶅皠鏈哄埗涓殑鏈閲嶈鐨勯儴鍒嗘槸鍏佽浣犳鏌ョ被鐨勭粨鏋?鐢ㄥ埌鐨凙PI鏈?
銆銆 java.lang.reflect.Field 榪斿洖瀛楁.
銆銆 java.reflect.Method 榪斿洖鏂規硶.
銆銆 java.lang.reflect.Constructor 榪斿洖鍙傛暟.
銆銆 鏂規硶鎸囬拡:java娌℃湁鏂規硶鎸囬拡,鎶婁竴涓柟娉曠殑鍦板潃浼犵粰鍙︿竴涓柟娉?鍙互鍦ㄥ悗闈㈣皟鐢ㄥ畠,鑰屾帴鍙ｆ槸鏇村ソ鐨勮В鍐蟲柟妗?
銆銆 23.鎺ュ彛(Interface)璇存槑綾昏鍋氫粈涔堣屼笉鎸囧畾濡備綍鍘誨仛,涓涓被鍙互瀹炵幇涓涓垨澶氫釜interface.
銆銆 24.鎺ュ彛涓嶆槸涓涓被,鑰屾槸瀵圭鍚堟帴鍙ｈ姹傜殑綾葷殑涓濂楄鑼?鑻ュ疄鐜頒竴涓帴鍙ｉ渶瑕?涓楠?
銆銆 1.澹版槑綾婚渶瑕佸疄鐜扮殑鎸囧畾鎺ュ彛.
銆銆 2.鎻愪緵鎺ュ彛涓殑鎵鏈夋柟娉曠殑瀹氫箟.
銆銆 澹版槑涓涓被瀹炵幇涓涓帴鍙ｉ渶瑕佷嬌鐢╥mplements 鍏抽敭瀛梒lass actionB implements Comparable 鍏禷ctionb闇瑕佹彁渚汣ompareTo鏂規硶,鎺ュ彛涓嶆槸綾?涓嶈兘鐢╪ew瀹炰緥鍖栦竴涓帴鍙?
銆銆 25.涓涓被鍙湁涓涓秴綾?浣嗕竴涓被鑳藉疄鐜板涓帴鍙?Java涓殑涓涓噸瑕佹帴鍙loneable
銆銆 26.鎺ュ彛鍜屽洖璋?緙栫▼涓涓父鐢ㄧ殑妯″紡鏄洖璋冩ā寮?鍦ㄨ繖縐嶆ā寮忎腑浣犲彲浠ユ寚瀹氬綋涓涓壒瀹氭椂闂村彂鐢熸椂鍥炶皟瀵硅薄涓婄殑鏂規硶.渚?ActionListener 鎺ュ彛鐩戝惉.
銆銆 綾諱技鐨凙PI鏈?java.swing.JOptionPane
銆銆銆銆銆銆銆銆 java.swing.Timer
銆銆銆銆銆銆銆銆 java.awt.Tookit
銆銆 27.瀵硅薄clone:clone鏂規硶鏄痮bject涓涓繚鎶ゆ柟娉?榪欐剰鍛崇潃浣犵殑浠ｇ爜涓嶈兘綆鍗曠殑璋冪敤瀹?
銆銆 28.鍐呴儴綾?涓涓唴閮ㄧ被鐨勫畾涔夋槸瀹氫箟鍦ㄥ彟涓涓唴閮ㄧ殑綾?
銆銆 鍘熷洜鏄?1.涓涓唴閮ㄧ被鐨勫璞¤兘澶熻闂垱寤哄畠鐨勫璞＄殑瀹炵幇,鍖呮嫭縐佹湁鏁版嵁
銆銆 2.瀵逛簬鍚屼竴涓寘涓殑鍏朵粬綾繪潵璇?鍐呴儴綾昏兘澶熼殣钘忚搗鏉?
銆銆 3.鍖垮悕鍐呴儴綾誨彲浠ュ緢鏂逛究鐨勫畾涔夊洖璋?
銆銆 4.浣跨敤鍐呴儴綾誨彲浠ラ潪甯告柟渚跨殑緙栧啓浜嬩歡椹卞姩紼嬪簭.
銆銆 29.浠ｇ悊綾?proxy):1.鎸囧畾鎺ュ彛瑕佹眰鎵鏈変唬鐮併2.object綾誨畾涔夌殑鎵鏈夌殑鏂規硶(toString equals)
銆銆 30.鏁版嵁綾誨瀷:Java鏄己璋冪被鍨嬬殑璇█,姣忎釜鍙橀噺閮藉繀欏誨厛鐢蟲槑瀹冮兘綾誨瀷,java涓誨叡鏈?涓熀鏈被鍨?4縐嶆槸鏁村瀷,2縐嶆槸嫻偣鍨?涓縐嶆槸瀛楃鍨?琚敤浜嶶nicode緙栫爜涓殑瀛楃,甯冨皵鍨?
浠ヤ笂鍐呭鎽樿嚜錛?a >http://java.ccidnet.com/art/3737/20060911/896379_1.html
]]>
闂涓錛?/strong>鎴戝０鏄庝簡浠涔堬紒
String s = "Hello world!";
璁稿浜洪兘鍋氳繃榪欐牱鐨勪簨鎯咃紝浣嗘槸錛屾垜浠埌搴曞０鏄庝簡浠涔堬紵鍥炵瓟閫氬父鏄細涓涓猄tring錛屽唴瀹規槸鈥淗ello world!鈥濄傝繖鏍鋒ā緋婄殑鍥炵瓟閫氬父鏄蹇典笉娓呯殑鏍規簮銆傚鏋滆鍑嗙‘鐨勫洖絳旓紝涓鍗婄殑浜哄ぇ姒備細鍥炵瓟閿欒銆?
榪欎釜璇彞澹版槑鐨勬槸涓涓寚鍚戝璞＄殑寮曠敤錛屽悕涓衡渟鈥濓紝鍙互鎸囧悜綾誨瀷涓篠tring鐨勪換浣曞璞★紝鐩墠鎸囧悜"Hello world!"榪欎釜String綾誨瀷鐨勫璞°傝繖灝辨槸鐪熸鍙戠敓鐨勪簨鎯呫傛垜浠茍娌℃湁澹版槑涓涓猄tring瀵硅薄錛屾垜浠彧鏄０鏄庝簡涓涓彧鑳芥寚鍚慡tring瀵硅薄鐨勫紩鐢ㄥ彉閲忋傛墍浠ワ紝濡傛灉鍦ㄥ垰鎵嶉偅鍙ヨ鍙ュ悗闈紝濡傛灉鍐嶈繍琛屼竴鍙ワ細
String string = s;
鎴戜滑鏄０鏄庝簡鍙﹀涓涓彧鑳芥寚鍚慡tring瀵硅薄鐨勫紩鐢紝鍚嶄負string錛屽茍娌℃湁絎簩涓璞′駭鐢燂紝string榪樻槸鎸囧悜鍘熸潵閭ｄ釜瀵硅薄錛屼篃灝辨槸錛屽拰s鎸囧悜鍚屼竴涓璞°?
闂浜岋細"=="鍜宔quals鏂規硶絀剁珶鏈変粈涔堝尯鍒紵
==鎿嶄綔絎︿笓闂ㄧ敤鏉ユ瘮杈冨彉閲忕殑鍊兼槸鍚︾浉絳夈傛瘮杈冨ソ鐞嗚В鐨勪竴鐐規槸錛?
int a=10;
int b=10;
鍒檃==b灝嗘槸true銆?
浣嗕笉濂界悊瑙ｇ殑鍦版柟鏄細
String a=new String("foo");
String b=new String("foo");
鍒檃==b灝嗚繑鍥瀎alse銆?
鏍規嵁鍓嶄竴甯栬榪囷紝瀵硅薄鍙橀噺鍏跺疄鏄竴涓紩鐢紝瀹冧滑鐨勫兼槸鎸囧悜瀵硅薄鎵鍦ㄧ殑鍐呭瓨鍦板潃錛岃屼笉鏄璞℃湰韜俛鍜宐閮戒嬌鐢ㄤ簡new鎿嶄綔絎︼紝鎰忓懗鐫灝嗗湪鍐呭瓨涓駭鐢熶袱涓唴瀹逛負"foo"鐨勫瓧絎︿覆錛屾棦鐒舵槸鈥滀袱涓濓紝瀹冧滑鑷劧浣嶄簬涓嶅悓鐨勫唴瀛樺湴鍧銆俛鍜宐鐨勫煎叾瀹炴槸涓や釜涓嶅悓鐨勫唴瀛樺湴鍧鐨勫鹼紝鎵浠ヤ嬌鐢?=="鎿嶄綔絎︼紝緇撴灉浼氭槸false銆傝瘹鐒訛紝a鍜宐鎵鎸囩殑瀵硅薄錛屽畠浠殑鍐呭閮芥槸"foo"錛屽簲璇ユ槸鈥滅浉絳夆濓紝浣嗘槸==鎿嶄綔絎﹀茍涓嶆秹鍙婂埌瀵硅薄鍐呭鐨勬瘮杈冦?
瀵硅薄鍐呭鐨勬瘮杈冿紝姝ｆ槸equals鏂規硶鍋氱殑浜嬨?
鐪嬩竴涓婳bject瀵硅薄鐨別quals鏂規硶鏄浣曞疄鐜扮殑錛?
boolean equals(Object o){
return this==o;
}
Object瀵硅薄榛樿浣跨敤浜?=鎿嶄綔絎︺傛墍浠ュ鏋滀綘鑷垱鐨勭被娌℃湁瑕嗙洊equals鏂規硶錛岄偅浣犵殑綾諱嬌鐢╡quals鍜屼嬌鐢?=浼氬緱鍒板悓鏍風殑緇撴灉銆傚悓鏍蜂篃鍙互鐪嬪嚭錛孫bject鐨別quals鏂規硶娌℃湁杈懼埌equals鏂規硶搴旇杈懼埌鐨勭洰鏍囷細姣旇緝涓や釜瀵硅薄鍐呭鏄惁鐩哥瓑銆傚洜涓虹瓟妗堝簲璇ョ敱綾葷殑鍒涘緩鑰呭喅瀹氾紝鎵浠bject鎶婅繖涓換鍔＄暀緇欎簡綾葷殑鍒涘緩鑰呫?
鐪嬩竴涓嬩竴涓瀬绔殑綾伙細
Class Monster{
private String content;
...
boolean equals(Object another){ return true;}
}
鎴戣鐩栦簡equals鏂規硶銆傝繖涓疄鐜頒細瀵艱嚧鏃犺Monster瀹炰緥鍐呭濡備綍錛屽畠浠箣闂寸殑姣旇緝姘歌繙榪斿洖true銆?
鎵浠ュ綋浣犳槸鐢╡quals鏂規硶鍒ゆ柇瀵硅薄鐨勫唴瀹規槸鍚︾浉絳夛紝璇蜂笉瑕佹兂褰撶劧銆傚洜涓哄彲鑳戒綘璁や負鐩哥瓑錛岃岃繖涓被鐨勪綔鑰呬笉榪欐牱璁や負錛岃岀被鐨別quals鏂規硶鐨勫疄鐜版槸鐢變粬鎺屾彙鐨勩傚鏋滀綘闇瑕佷嬌鐢╡quals鏂規硶錛屾垨鑰呬嬌鐢ㄤ換浣曞熀浜庢暎鍒楃爜鐨勯泦鍚堬紙HashSet,HashMap,HashTable錛夛紝璇峰療鐪嬩竴涓媕ava doc浠ョ‘璁よ繖涓被鐨別quals閫昏緫鏄浣曞疄鐜扮殑銆?
闂涓夛細String鍒板簳鍙樹簡娌℃湁錛?/font>
娌℃湁銆傚洜涓篠tring琚璁℃垚涓嶅彲鍙?immutable)綾伙紝鎵浠ュ畠鐨勬墍鏈夊璞￠兘鏄笉鍙彉瀵硅薄銆傝鐪嬩笅鍒椾唬鐮侊細
String s = "Hello";
s = s + " world!";
s鎵鎸囧悜鐨勫璞℃槸鍚︽敼鍙樹簡鍛紵浠庢湰緋誨垪絎竴綃囩殑緇撹寰堝鏄撳鍑鴻繖涓粨璁恒傛垜浠潵鐪嬬湅鍙戠敓浜嗕粈涔堜簨鎯呫傚湪榪欐浠ｇ爜涓紝s鍘熷厛鎸囧悜涓涓猄tring瀵硅薄錛屽唴瀹規槸"Hello"錛岀劧鍚庢垜浠s榪涜浜?鎿嶄綔錛岄偅涔坰鎵鎸囧悜鐨勯偅涓璞℃槸鍚﹀彂鐢熶簡鏀瑰彉鍛紵絳旀鏄病鏈夈傝繖鏃訛紝s涓嶆寚鍚戝師鏉ラ偅涓璞′簡錛岃屾寚鍚戜簡鍙︿竴涓猄tring瀵硅薄錛屽唴瀹逛負"Hello world!"錛屽師鏉ラ偅涓璞¤繕瀛樺湪浜庡唴瀛樹箣涓紝鍙槸s榪欎釜寮曠敤鍙橀噺涓嶅啀鎸囧悜瀹冧簡銆?
閫氳繃涓婇潰鐨勮鏄庯紝鎴戜滑寰堝鏄撳鍑哄彟涓涓粨璁猴紝濡傛灉緇忓父瀵瑰瓧絎︿覆榪涜鍚勭鍚勬牱鐨勪慨鏀癸紝鎴栬呰錛屼笉鍙瑙佺殑淇敼錛岄偅涔堜嬌鐢⊿tring鏉ヤ唬琛ㄥ瓧絎︿覆鐨勮瘽浼氬紩璧峰緢澶х殑鍐呭瓨寮閿銆傚洜涓篠tring瀵硅薄寤虹珛涔嬪悗涓嶈兘鍐嶆敼鍙橈紝鎵浠ュ浜庢瘡涓涓笉鍚岀殑瀛楃涓詫紝閮介渶瑕佷竴涓猄tring瀵硅薄鏉ヨ〃紺恒傝繖鏃訛紝搴旇鑰冭檻浣跨敤StringBuffer綾伙紝瀹冨厑璁鎬慨鏀癸紝鑰屼笉鏄瘡涓笉鍚岀殑瀛楃涓查兘瑕佺敓鎴愪竴涓柊鐨勫璞°傚茍涓旓紝榪欎袱縐嶇被鐨勫璞¤漿鎹㈠崄鍒嗗鏄撱?
鍚屾椂錛屾垜浠繕鍙互鐭ラ亾錛屽鏋滆浣跨敤鍐呭鐩稿悓鐨勫瓧絎︿覆錛屼笉蹇呮瘡嬈￠兘new涓涓猄tring銆備緥濡傛垜浠鍦ㄦ瀯閫犲櫒涓涓涓悕鍙玸鐨凷tring寮曠敤鍙橀噺榪涜鍒濆鍖栵紝鎶婂畠璁劇疆涓哄垵濮嬪鹼紝搴斿綋榪欐牱鍋氾細
public class Demo {
private String s;
...
public Demo {
s = "Initial Value";
}
...
}
鑰岄潪
s = new String("Initial Value");
鍚庤呮瘡嬈￠兘浼氳皟鐢ㄦ瀯閫犲櫒錛岀敓鎴愭柊瀵硅薄錛屾ц兘浣庝笅涓斿唴瀛樺紑閿澶э紝騫朵笖娌℃湁鎰忎箟錛屽洜涓篠tring瀵硅薄涓嶅彲鏀瑰彉錛屾墍浠ュ浜庡唴瀹圭浉鍚岀殑瀛楃涓詫紝鍙涓涓猄tring瀵硅薄鏉ヨ〃紺哄氨鍙互浜嗐備篃灝辮錛屽嬈¤皟鐢ㄤ笂闈㈢殑鏋勯犲櫒鍒涘緩澶氫釜瀵硅薄錛屼粬浠殑String綾誨瀷灞炴閮芥寚鍚戝悓涓涓璞°?
涓婇潰鐨勭粨璁鴻繕鍩轟簬榪欐牱涓涓簨瀹烇細瀵逛簬瀛楃涓插父閲忥紝濡傛灉鍐呭鐩稿悓錛孞ava璁や負瀹冧滑浠ｈ〃鍚屼竴涓猄tring瀵硅薄銆傝岀敤鍏抽敭瀛梟ew璋冪敤鏋勯犲櫒錛屾繪槸浼氬垱寤轟竴涓柊鐨勫璞★紝鏃犺鍐呭鏄惁鐩稿悓銆?
鑷充簬涓轟粈涔堣鎶奡tring綾昏璁℃垚涓嶅彲鍙樼被錛屾槸瀹冪殑鐢ㄩ斿喅瀹氱殑銆傚叾瀹炰笉鍙猄tring錛屽緢澶欽ava鏍囧噯綾誨簱涓殑綾婚兘鏄笉鍙彉鐨勩傚湪寮鍙戜竴涓郴緇熺殑鏃跺欙紝鎴戜滑鏈夋椂鍊欎篃闇瑕佽璁′笉鍙彉綾伙紝鏉ヤ紶閫掍竴緇勭浉鍏崇殑鍊鹼紝榪欎篃鏄潰鍚戝璞℃濇兂鐨勪綋鐜般備笉鍙彉綾繪湁涓浜涗紭鐐癸紝姣斿鍥犱負瀹冪殑瀵硅薄鏄彧璇葷殑錛屾墍浠ュ綰跨▼騫跺彂璁塊棶涔熶笉浼氭湁浠諱綍闂銆傚綋鐒朵篃鏈変竴浜涚己鐐癸紝姣斿姣忎釜涓嶅悓鐨勭姸鎬侀兘瑕佷竴涓璞℃潵浠ｈ〃錛屽彲鑳戒細閫犳垚鎬ц兘涓婄殑闂銆傛墍浠ava鏍囧噯綾誨簱榪樻彁渚涗簡涓涓彲鍙樼増鏈紝鍗砈tringBuffer銆?
闂鍥涳細final鍏抽敭瀛楀埌搴曚慨楗頒簡浠涔堬紵
final浣垮緱琚慨楗扮殑鍙橀噺"涓嶅彉"錛屼絾鏄敱浜庡璞″瀷鍙橀噺鐨勬湰璐ㄦ槸鈥滃紩鐢ㄢ濓紝浣垮緱鈥滀笉鍙樷濅篃鏈変簡涓ょ鍚箟錛氬紩鐢ㄦ湰韜殑涓嶅彉錛屽拰寮曠敤鎸囧悜鐨勫璞′笉鍙樸?
寮曠敤鏈韓鐨勪笉鍙橈細
final StringBuffer a=new StringBuffer("immutable");
final StringBuffer b=new StringBuffer("not immutable");
a=b;//緙栬瘧鏈熼敊璇?
寮曠敤鎸囧悜鐨勫璞′笉鍙橈細
final StringBuffer a=new StringBuffer("immutable");
a.append(" broken!"); //緙栬瘧閫氳繃
鍙錛宖inal鍙寮曠敤鐨勨滃尖?涔熷嵆瀹冩墍鎸囧悜鐨勯偅涓璞＄殑鍐呭瓨鍦板潃)鏈夋晥錛屽畠榪嬌寮曠敤鍙兘鎸囧悜鍒濆鎸囧悜鐨勯偅涓璞★紝鏀瑰彉瀹冪殑鎸囧悜浼氬鑷寸紪璇戞湡閿欒銆傝嚦浜庡畠鎵鎸囧悜鐨勫璞＄殑鍙樺寲錛宖inal鏄笉璐熻矗鐨勩傝繖寰堢被浼?=鎿嶄綔絎︼細==鎿嶄綔絎﹀彧璐熻矗寮曠敤鐨勨滃尖濈浉絳夛紝鑷充簬榪欎釜鍦板潃鎵鎸囧悜鐨勫璞″唴瀹規槸鍚︾浉絳夛紝==鎿嶄綔絎︽槸涓嶇鐨勩?
鐞嗚Вfinal闂鏈夊緢閲嶈鐨勫惈涔夈傝澶氱▼搴忔紡媧為兘鍩轟簬姝?---final鍙兘淇濊瘉寮曠敤姘歌繙鎸囧悜鍥哄畾瀵硅薄錛屼笉鑳戒繚璇侀偅涓璞＄殑鐘舵佷笉鍙樸傚湪澶氱嚎紼嬬殑鎿嶄綔涓?涓涓璞′細琚涓嚎紼嬪叡浜垨淇敼錛屼竴涓嚎紼嬪瀵硅薄鏃犳剰璇嗙殑淇敼鍙兘浼氬鑷村彟涓涓嬌鐢ㄦ瀵硅薄鐨勭嚎紼嬪穿婧冦備竴涓敊璇殑瑙ｅ喅鏂規硶灝辨槸鍦ㄦ瀵硅薄鏂板緩鐨勬椂鍊欐妸瀹冨０鏄庝負final錛屾剰鍥句嬌寰楀畠鈥滄案榪滀笉鍙樷濄傚叾瀹為偅鏄緬鍔崇殑銆?
闂浜旓細鍒板簳瑕佹庝箞鏍峰垵濮嬪寲錛?/font>
鏈棶棰樿璁哄彉閲忕殑鍒濆鍖栵紝鎵浠ュ厛鏉ョ湅涓涓婮ava涓湁鍝簺縐嶇被鐨勫彉閲忋?
1. 綾葷殑灞炴э紝鎴栬呭彨鍊煎煙
2. 鏂規硶閲岀殑灞閮ㄥ彉閲?
3. 鏂規硶鐨勫弬鏁?
瀵逛簬絎竴縐嶅彉閲忥紝Java铏氭嫙鏈轟細鑷姩榪涜鍒濆鍖栥傚鏋滅粰鍑轟簡鍒濆鍊鹼紝鍒欏垵濮嬪寲涓鴻鍒濆鍊箋傚鏋滄病鏈夌粰鍑猴紝鍒欐妸瀹冨垵濮嬪寲涓鴻綾誨瀷鍙橀噺鐨勯粯璁ゅ垵濮嬪箋?
int綾誨瀷鍙橀噺榛樿鍒濆鍊間負0
float綾誨瀷鍙橀噺榛樿鍒濆鍊間負0.0f
double綾誨瀷鍙橀噺榛樿鍒濆鍊間負0.0
boolean綾誨瀷鍙橀噺榛樿鍒濆鍊間負false
char綾誨瀷鍙橀噺榛樿鍒濆鍊間負0(ASCII鐮?
long綾誨瀷鍙橀噺榛樿鍒濆鍊間負0
鎵鏈夊璞″紩鐢ㄧ被鍨嬪彉閲忛粯璁ゅ垵濮嬪間負null錛屽嵆涓嶆寚鍚戜換浣曞璞°傛敞鎰忔暟緇勬湰韜篃鏄璞★紝鎵浠ユ病鏈夊垵濮嬪寲鐨勬暟緇勫紩鐢ㄥ湪鑷姩鍒濆鍖栧悗鍏跺間篃鏄痭ull銆?
瀵逛簬涓ょ涓嶅悓鐨勭被灞炴э紝static灞炴т笌instance灞炴э紝鍒濆鍖栫殑鏃舵満鏄笉鍚岀殑銆俰nstance灞炴у湪鍒涘緩瀹炰緥鐨勬椂鍊欏垵濮嬪寲錛宻tatic灞炴у湪綾誨姞杞斤紝涔熷氨鏄涓嬈＄敤鍒拌繖涓被鐨勬椂鍊欏垵濮嬪寲錛屽浜庡悗鏉ョ殑瀹炰緥鐨勫垱寤猴紝涓嶅啀嬈¤繘琛屽垵濮嬪寲銆傝繖涓棶棰樹細鍦ㄤ互鍚庣殑緋誨垪涓繘琛岃緇嗚璁恒?
瀵逛簬絎簩縐嶅彉閲忥紝蹇呴』鏄庣‘鍦拌繘琛屽垵濮嬪寲銆傚鏋滃啀娌℃湁鍒濆鍖栦箣鍓嶅氨璇曞浘浣跨敤瀹冿紝緙栬瘧鍣ㄤ細鎶楄銆傚鏋滃垵濮嬪寲鐨勮鍙ュ湪try鍧椾腑鎴杋f鍧椾腑錛屼篃蹇呴』瑕佽瀹冨湪絎竴嬈′嬌鐢ㄥ墠涓瀹氳兘澶熷緱鍒拌祴鍊箋備篃灝辨槸璇達紝鎶婂垵濮嬪寲璇彞鏀懼湪鍙湁if鍧楃殑鏉′歡鍒ゆ柇璇彞涓紪璇戝櫒涔熶細鎶楄錛屽洜涓烘墽琛岀殑鏃跺欏彲鑳戒笉絎﹀悎if鍚庨潰鐨勫垽鏂潯浠訛紝濡傛涓鏉ュ垵濮嬪寲璇彞灝變笉浼氳鎵ц浜嗭紝榪欏氨榪濆弽浜嗗眬閮ㄥ彉閲忎嬌鐢ㄥ墠蹇呴』鍒濆鍖栫殑瑙勫畾銆備絾濡傛灉鍦╡lse鍧椾腑涔熸湁鍒濆鍖栬鍙ワ紝灝卞彲浠ラ氳繃緙栬瘧錛屽洜涓烘棤璁哄浣曪紝鎬繪湁鑷沖皯涓鏉″垵濮嬪寲璇彞浼氳鎵ц錛屼笉浼氬彂鐢熶嬌鐢ㄥ墠鏈鍒濆鍖栫殑浜嬫儏銆傚浜巘ry-catch涔熸槸涓鏍鳳紝濡傛灉鍙湁鍦╰ry鍧楅噷鎵嶆湁鍒濆鍖栬鍙ワ紝緙栬瘧閮ㄩ氳繃銆傚鏋滃湪catch鎴杅inally閲屼篃鏈夛紝鍒欏彲浠ラ氳繃緙栬瘧銆傛諱箣錛岃淇濊瘉灞閮ㄥ彉閲忓湪浣跨敤涔嬪墠涓瀹氳鍒濆鍖栦簡銆傛墍浠ワ紝涓涓ソ鐨勫仛娉曟槸鍦ㄥ０鏄庝粬浠殑鏃跺欏氨鍒濆鍖栦粬浠紝濡傛灉涓嶇煡閬撹鍑轟簨鍖栨垚浠涔堝煎ソ錛屽氨鐢ㄤ笂闈㈢殑榛樿鍊煎惂錛?
鍏跺疄絎笁縐嶅彉閲忓拰絎簩縐嶆湰璐ㄤ笂鏄竴鏍風殑錛岄兘鏄柟娉曚腑鐨勫眬閮ㄥ彉閲忋傚彧涓嶈繃浣滀負鍙傛暟錛岃偗瀹氭槸琚垵濮嬪寲榪囩殑錛屼紶鍏ョ殑鍊煎氨鏄垵濮嬪鹼紝鎵浠ヤ笉闇瑕佸垵濮嬪寲銆?
闂鍏細instanceof鏄粈涔堜笢涓滐紵
instanceof鏄疛ava鐨勪竴涓簩鍏冩搷浣滅錛屽拰==錛?gt;錛?lt;鏄悓涓綾諱笢涓溿傜敱浜庡畠鏄敱瀛楁瘝緇勬垚鐨勶紝鎵浠ヤ篃鏄疛ava鐨勪繚鐣欏叧閿瓧銆傚畠鐨勪綔鐢ㄦ槸嫻嬭瘯瀹冨乏杈圭殑瀵硅薄鏄惁鏄畠鍙寵竟鐨勭被鐨勫疄渚嬶紝榪斿洖boolean綾誨瀷鐨勬暟鎹備婦涓緥瀛愶細
String s = "I AM an Object!";
boolean isObject = s instanceof Object;
鎴戜滑澹版槑浜嗕竴涓猄tring瀵硅薄寮曠敤錛屾寚鍚戜竴涓猄tring瀵硅薄錛岀劧鍚庣敤instancof鏉ユ祴璇曞畠鎵鎸囧悜鐨勫璞℃槸鍚︽槸Object綾葷殑涓涓疄渚嬶紝鏄劇劧錛岃繖鏄湡鐨勶紝鎵浠ヨ繑鍥瀟rue錛屼篃灝辨槸isObject鐨勫間負True銆?
instanceof鏈変竴浜涚敤澶勩傛瘮濡傛垜浠啓浜嗕竴涓鐞嗚處鍗曠殑緋葷粺錛屽叾涓湁榪欐牱涓変釜綾伙細
public class Bill {//鐪佺暐緇嗚妭}
public class PhoneBill extends Bill {//鐪佺暐緇嗚妭}
public class GasBill extends Bill {//鐪佺暐緇嗚妭}
鍦ㄥ鐞嗙▼搴忛噷鏈変竴涓柟娉曪紝鎺ュ彈涓涓狟ill綾誨瀷鐨勫璞★紝璁＄畻閲戦銆傚亣璁句袱縐嶈處鍗曡綆楁柟娉曚笉鍚岋紝鑰屼紶鍏ョ殑Bill瀵硅薄鍙兘鏄袱縐嶄腑鐨勪換浣曚竴縐嶏紝鎵浠ヨ鐢╥nstanceof鏉ュ垽鏂細
public double calculate(Bill bill) {
if (bill instanceof PhoneBill) {
//璁＄畻鐢佃瘽璐﹀崟
}
if (bill instanceof GasBill) {
//璁＄畻鐕冩皵璐﹀崟
}
...
}
榪欐牱灝卞彲浠ョ敤涓涓柟娉曞鐞嗕袱縐嶅瓙綾匯?
鐒惰岋紝榪欑鍋氭硶閫氬父琚涓烘槸娌℃湁濂藉ソ鍒╃敤闈㈠悜瀵硅薄涓殑澶氭佹с傚叾瀹炰笂闈㈢殑鍔熻兘瑕佹眰鐢ㄦ柟娉曢噸杞藉畬鍏ㄥ彲浠ュ疄鐜幫紝榪欐槸闈㈠悜瀵硅薄鍙樻垚搴旀湁鐨勫仛娉曪紝閬垮厤鍥炲埌緇撴瀯鍖栫紪紼嬫ā寮忋傚彧瑕佹彁渚涗袱涓悕瀛楀拰榪斿洖鍊奸兘鐩稿悓錛屾帴鍙楀弬鏁扮被鍨嬩笉鍚岀殑鏂規硶灝卞彲浠ヤ簡錛?
public double calculate(PhoneBill bill) {
//璁＄畻鐢佃瘽璐﹀崟
}
public double calculate(GasBill bill) {
//璁＄畻鐕冩皵璐﹀崟
}
鎵浠ワ紝浣跨敤instanceof鍦ㄧ粷澶у鏁版儏鍐典笅騫朵笉鏄帹鑽愮殑鍋氭硶錛屽簲褰撳ソ濂藉埄鐢ㄥ鎬併?img src ="http://m.tkk7.com/flustar/aggbug/89073.html" width = "1" height = "1" />
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