闈㈣瘯 java 二
聽 聽 缁х画鏄ㄥぉ鐨勯潰璇曢銆?/p>
聽 聽 鏈轰細鏄暀缁欐湁鍑嗗鐨勪汉锛屽ぇ瀹跺姞娌癸紒鎴戜篃鍔犳补锛?/p>
聽 聽1.聽娴嬭瘯鐢熷懡鍛ㄦ湡銆佹祴璇曡繃绋嬪垎涓哄嚑涓樁娈碉紝浠ュ強鍚勯樁娈电殑鍚箟锛?/span>
聽 聽杩欎釜浣犲氨绠椾笉浜嗚В锛屼綘涔熻璁颁綇銆傞潰璇曠殑鏃跺€欎篃浼氶棶閬撶殑銆?/span>
聽 聽鐢熷懡鍛ㄦ湡锛氭祴璇曡鍒?----娴嬭瘯璁捐-----娴嬭瘯寮€鍙?----娴嬭瘯鎵ц-----娴嬭瘯璇勪及
聽 聽娴嬭瘯杩囩▼锛氬崟鍏冩祴璇?----闆嗘垚娴嬭瘯------纭娴嬭瘯-----绯荤粺娴嬭瘯
聽 聽 聽 鍗曞厓娴嬭瘯鍙堢О妯″潡娴嬭瘯锛岃蒋浠惰璁′腑鏈€灏忕殑涓€涓ā鍧?-绋嬪簭妯″潡銆傝繘琛屾纭€ф楠岀殑娴嬭瘯宸ヤ綔銆?/span>
聽 聽 聽 闆嗘垚娴嬭瘯涔熷彨缁勮娴嬭瘯鍜岃仈鍚堟祴璇曪紝鍦ㄥ崟鍏冩祴璇曠殑鍩虹涓婏紝闇€瑕佸皢鎵€鏈夌殑璁捐妯″潡鎸夌収姒傝璁捐鐨勯渶姹傝鏄庝功鍜岃缁嗚璁¤鏄庝功鐨勮姹傝繘琛岀粍瑁呫€?/span>
聽 聽 聽 纭娴嬭瘯灏辨槸楠岃瘉杞欢鐨勫姛鑳藉拰鎬ц兘鍜屽叾浠栨€ц兘鏄惁鍜岀敤鎴疯姹備竴鑷淬€?/span>
聽 聽 聽聽绯荤粺娴嬭瘯鏃跺皢閫氳繃闆嗘垚娴嬭瘯鐨勮蒋浠讹紝浣滀负鏁翠釜鍩轰簬璁＄畻鏈虹郴缁熺殑涓€涓厓绱狅紝涓庤绠楁満纭欢銆佸璁俱€佹煇浜涙敮鎸佽蒋浠躲€佹暟鎹拰浜哄憳绛夊叾浠栫郴缁熷厓绱犵粨鍚堝湪涓€璧凤紝鍦ㄥ疄闄呮垨鑰呮ā鎷熻繍琛屼娇鐢ㄧ幆澧冧笅锛屽璁＄畻鏈虹郴缁熻繘琛屼竴绯诲垪娴嬭瘯銆傚叾鐩殑鍦ㄤ簬閫氳繃涓庣郴缁熼渶姹傚畾涔変綔姣旇緝锛?/span>鍙戠幇杞欢涓庣郴缁熷畾涔変笉绗﹀悎鎴栦笌涔嬬煕鐩剧殑鍦版柟銆?/span>
聽
聽
聽 2.java鍨冨溇鏀堕泦鍣紵
锛?span style="font-family: Calibri;">1锛夊彂鐜版棤鐢ㄤ俊鎭璞?/span>
锛?span style="font-family: Calibri;">2锛夊洖鏀惰鏃犵敤瀵硅薄鍗犵敤鐨勫唴瀛樼┖闂达紝浣胯绌洪棿鍙绋嬪簭鍐嶆浣跨敤
聽
鏈変袱涓潯浠朵細瑙﹀彂涓?span style="font-family: Calibri;">GC:
1)褰撳簲鐢ㄧ▼搴忕┖闂叉椂,鍗虫病鏈夊簲鐢ㄧ嚎绋嬪湪杩愯鏃?/span>,GC浼氳璋冪敤銆傚洜涓?/span>GC鍦ㄤ紭鍏堢骇鏈€浣庣殑绾跨▼涓繘琛?/span>,鎵€浠ュ綋搴旂敤蹇欐椂,GC绾跨▼灏变笉浼氳璋冪敤,浣嗕互涓嬫潯浠堕櫎澶栥€?/span>
銆€銆€2)Java鍫嗗唴瀛樹笉瓒虫椂,GC浼氳璋冪敤銆?褰撳簲鐢ㄧ嚎绋嬪湪杩愯,骞跺湪杩愯杩囩▼涓垱寤烘柊瀵硅薄,鑻ヨ繖鏃跺唴瀛樼┖闂翠笉瓒?/span>,JVM灏变細寮哄埗鍦拌皟鐢?/span>GC绾跨▼,浠ヤ究鍥炴敹鍐呭瓨鐢ㄤ簬鏂扮殑鍒嗛厤銆傝嫢GC涓€娆′箣鍚庝粛涓嶈兘婊¤冻 鍐呭瓨鍒嗛厤鐨勮姹?/span>,JVM浼氬啀杩涜涓ゆGC浣滆繘涓€姝ョ殑灏濊瘯,鑻ヤ粛鏃犳硶婊¤冻瑕佹眰,鍒?JVM灏嗘姤鈥渙ut of memory鈥?/span>鐨勯敊璇?/span>,Java搴旂敤灏嗗仠姝€?/span>
聽
聽
聽 聽3.浠€涔堟槸Java铏氭嫙鏈猴紵涓轰粈涔?/span>Java琚О浣滄槸鈥滃钩鍙版棤鍏?聽鐨勭紪绋嬭瑷€鈥濓紵
铏氭嫙鏈?span style="font-family: Calibri;">(JVM)鏄竴涓繛鎺ユ搷浣滅郴缁熷拰JAVA绋嬪簭鐨勩€傚洜涓鸿兘杩炴帴鎵€浠?/span>JAVA绋嬪簭鍦ㄧ紪璇戜箣鍚庯紝灏卞彲浠ュ湪浠讳綍涓€鍙拌绠楁満涓婅繍琛屻€傚洜姝?/span>JAVA琚О涓衡€滀笌骞冲彴鏃犲叧鈥濄€?/span>
聽
聽
4.JDK鍜?/span>JRE鐨勫尯鍒槸浠€涔堬紵
聽 聽 JDK灏辨槸(Java Development Kit)聽鏄拡瀵笿ava寮€鍙戝憳鐨勪骇鍝侊紝鏄暣涓狫ava鐨勬牳蹇冿紝鍖呮嫭浜咼ava杩愯鐜JRE銆佷竴鍫咼ava宸ュ叿锛坖avac/java/jdb绛夛級鍜孞ava鍩虹鐨勭被搴擄紙鍗矹ava API 鍖呮嫭rt.jar锛夈€偮?/span>
聽
JRE鏄?/span>(Java Runtime Enviroment)聽鏄繍琛?span style="font-family: Calibri;">JAVA绋嬪簭鎵€蹇呴』鐨勭幆澧冪殑闆嗗悎锛屽寘鍚?/span>JVM鏍囧噯瀹炵幇鍙?/span>Java鏍稿績绫诲簱銆?/span>JVM鏄?/span>Java Virtual Machine锛?/span>Java铏氭嫙鏈猴級鐨勭缉鍐欙紝鏄暣涓?/span>java瀹炵幇璺ㄥ钩鍙扮殑鏈€鏍稿績鐨勯儴鍒嗭紝鑳藉杩愯浠?/span>Java璇█鍐欎綔鐨勮蒋浠剁▼搴?/span>銆?/span>
聽
聽
聽 聽 5.鏄惁鍙互鍦?/span>static鐜涓闂潪static鍙橀噺锛?/span>
聽 聽 聽涓嶈兘鐩存帴璁块棶,闇€瑕佸厛鍒涘缓鍑烘潵闈?/span>static鍙橀噺鎵€鍦ㄧ殑绫?/span>,鐒跺悗閫氳繃瀹氫箟鐨勮繖涓被闈?/span>static鍙橀噺銆?/span>
聽
public class Test{
private static int s=200;
public static void main(String [] args){
new Test().staticTest();
}
private void staticTest(){
System.out println(s);
}
}
聽 聽 聽 聽 聽 鏈€鍚庤緭鍑猴細200锛?/span>
聽
聽 聽
聽 聽 聽 聽 6.Java鏀寔鐨勬暟鎹被鍨嬫湁鍝簺锛熶粈涔堟槸鑷姩鎷嗚绠憋紵
聽 聽 聽 聽鍏ぇ鍩虹鏁版嵁绫诲瀷锛歜yte , short 锛?int 锛?long , float , double , boolean , char.
聽 聽 聽 聽瀵硅薄鏁版嵁绫诲瀷锛?/span>Byte,Character,Integer,Long,Float,Double,Boolean,Short锛孲tring銆?/span>
聽 聽 聽聽鑷姩瑁呯鏄?/span>Java缂栬瘧鍣ㄥ湪鍩烘湰鏁版嵁绫诲瀷鍜屽搴旂殑瀵硅薄鍖呰绫诲瀷涔嬮棿鍋氱殑涓€涓浆鍖栥€傛瘮濡傦細鎶?/span>int杞寲鎴?/span>Integer锛?/span>double杞寲鎴?/span>double锛岀瓑绛夈€傚弽涔嬪氨鏄嚜鍔ㄦ媶绠便€?/span>
聽
聽
聽 聽 聽 聽 7.Java涓殑鏂规硶瑕嗙洊(Overriding)鍜屾柟娉曢噸杞?/span>(Overloading)鏄粈涔堟剰鎬濓紵
聽 聽 聽 聽 聽聽(Overloading)閲嶈浇灏辨槸鍏锋湁鐩稿悓鍑芥暟鍚嶏紝杩斿洖绫诲瀷鍙互涓嶅悓锛屽弬鏁颁釜鏁般€侀『搴忋€佺被鍨嬩笉鍚岀殑鍑芥暟銆?/span>
聽
聽 聽 聽 聽 聽聽
public class OverloadingTes{
String name;
int age;
void print(){
System.out.println("濮撳悕锛?+ name + "/t骞撮緞锛?+age);
}
void print(String a,int b){
System.out.println("濮撳悕锛?+ a+ "/t骞撮緞锛?+b);
}
void print(String a,int b,int c){
System.out.println("濮撳悕锛?+ a+ "/t骞撮緞锛?+b+"/tID鍙凤細"+c);
}
}
聽 聽 聽 聽 聽 聽聽(Overriding)閲嶅啓瀹冩槸鎸囧瓙绫诲拰鐖剁被鐨勫叧绯伙紝瀛愮被閲嶅啓浜嗙埗绫荤殑鏂规硶锛屼絾鏂规硶鍚嶃€佸弬鏁扮被鍨嬨€佸弬鏁颁釜鏁板繀椤荤浉鍚?
聽 聽 聽 聽 聽 聽 聽
public class Main{
public static void main(String[] args) {
new Son().eat();
((Father) new Son()).eat();
}
}
public class Father{
public void eat(){
System.out.println("father");
}
}
public class Son extends Father {
public void eat(){
System.out.println("son");
}
}
聽
聽
聽 聽 聽 聽8.Java涓紝浠€涔堟槸鏋勯€犲嚱鏁帮紵浠€涔堟槸鏋勯€犲嚱鏁伴噸杞斤紵浠€涔堟槸澶嶅埗鏋勯€犲嚱鏁?
聽 聽 聽 聽聽a銆?/span>java绫讳腑鐨勪竴绉嶇壒娈婃柟娉曪紝鏂规硶鍚嶄笌绫诲悕鐩稿悓锛屼竴鑸敤鏉ュ垵濮嬪寲涓€浜涙垚鍛樺彉閲?/span>
聽 聽 b銆侀噸杞芥瀯閫犲嚱鏁?/span>灏辨槸涓€涓被涓紝鍙傛暟涓嶄竴鏍风殑澶氫釜鏋勯€犲嚱鏁?/span>
聽 聽 聽 聽聽
聽
聽
聽
聽
聽
聽
聽
聽
聽