Java+语言基础

JavajavaUnicodeUnicodeASCIIASCII816UnicodeASCIIJavaJava31.//////2./***//**//**/3./****/JDKJavadocJavadoc@docHTMLJava0~9JavaUnicode261ASCIIAZaz2093_$4unicode0xc0a.Javab.c.JavaJavaJavaabstractbooleanbreakbytebyvaluecasecastclassconstcontinuedefaultdodoublefalsefinalfinallyfloatforgotoifimplementsimportinstanceofintinterfacelongnativepackageprivateprotectedpublicreturnshortstaticsuperswitchsynchronizedthisthreadsafethrowtransienttruetryvoidwhileJavaJava(){}[];‘javaJava1.Java123,456,000123830x0X0x12329132intlongLl123L642.10103.141591010Ee1.235e5Java32fF64dD3.1f3.1F3.1d3.1D3.truefalse4.Java’a’Java\\r\n\t\b\f\\\’\”\ddd\XddUnicode\Udddd5.HelloJavaunsigenedjavajava4byteshortintlong12481.bytebyte8128127bytea;//abyted=0x68;//dd0x682.shortshort163276832767shorta;shortd=0x68bb;3.intint3221474836482147483647intbyteshortintJavaintshorta;shortd=0x68bb1111;4.longlong6492233720368477808L92233720368477807Llonga;longd=0x68bb111122223333floatdouble1.floatfloat323.4e0383.4e038floata;floatd=3.1418F;2.doubledouble641.7e3081.7e308Javasincossqrtdoublea;doubled=3.1418D;char16065535charUnicode\uUnicodechara=‘s’;chard=‘\u005c’;Javabooleantruefalsebooleana=true;booleand=false;0123456789101112131415161718Javaisalanguage.substring(10,18)1-2substring0123456789101112131415161718Javaisalanguage.charAt(0)charAt(11)charAt(length()-1)1-1chatAt0123456789101112131415161718Javaisalanguage.indexOf(‘a’)indexOf(“language”)lastIndexOf(‘a’)1-3indexOfzzzJava;JavaJava1.2.Stringname;Java1.Java2.Javatypevalueinta=200;byteb=(byte)a;1byteshortintintlonglongLlint2floatfloatdoubledoubledoubleJavaJava44Java1x=18;2Java11Java+-*/%++--+=-=*=/=%=1booleancharJavacharint23411truefalseJava==!===Java&|^&&||!!booleantruefalselongintshortcharbyteJava~&|^0&=|=^====01.~0110~(11110000)=000011112.&&110(00001111)&(11110000)=000000003.|11(11110000)|(00001111)=111111114.^10(00110001)^(11000001)=111100005.0(00001111)2=00111100226.(00001111)2=0000001127.0(10001111)2=001000118.==d=2d=d2Java?[]()instanceof+1.?12:31true221false33x=(32)?8:9x82.()[]Java[]inta[]=newint[5];a[0]=8;3.instanceoftruefalseifinstanceof{......}Stringstr=“888”;if(strinstanceofString){System.out.println(str);}4.JavaString2Strings=“ab”+“cd”;//s”abcd”Java[].()()!~++--+()–()()()new*/%+-==instanceof==!=&^|&&||?:=+=-=*=/=%=&=|=^====1.6JavaJava3JavagotoJavabreakcontinuegotobreakcontinueifJava231ifif(condition)statement1;[elsestatement2;]inta=7;intb=8;if(ab)System.out.println(a);elseSystem.out.println(b);81conditionbooleantruestatement1falsestatement22statement2ififififif(condition)if(condition)statement1;elsestatement2;elseif(condition)statement1;elsestatement2;3ifelseififelseififif(condition)statement;elseif(condition)statement;elseif(condition)statement;……elsestatement;ififelseelseswitchifswitchswitch(expression){casevalue1:1break;casevalue2:2break;……casevaluen:nbreak;default:n+1}intx=8;switch(x){case1:System.out.println(1);break;case8:System.out.println(8);break;case5:System.out.println(5);break;}81expressionvaluecharbyteshortintvalue2switchexpressioncasecasecaseexpressiondefaultdefaultswitchifelse3breakswitchswitch4casewhileJavawhile(condition){//break;continue;return;}intx=0;while(x8){System.out.println(x);x=x+1;}012345671conditionwhile2return3break4continuewhilecontinuedowhiledo{//}while(condition)intx=0;do{x=x+1;System.out.println(x);}while(x8)12345678forJavafor(initialization;condition;increment){//}for(intx=0;x8;x++){System.out.println(x);}012345671initializationfor2conditionfor3increment4forinitializationconditiontrueincrementconditionfalsefor1.7OOPOOPOOP2.2.110mp1090rpm9052.2.2“”OOPOOP2.2.31.2.3.2.2.4javaJavaJava2.2.5()()2.2.62.2.7Java1.81.8.1Javaclassclassextendsimplementstypeinstance-varable1;typeinstance-varable2;typeinstance-varable3;themethodname1(parameter-list){method-body;}themethodname2(parameter-list){method-body;}themethodnameN(parameter-list){method-body;}1class2Javaclass3yabstractyfinalypublicyprivate4extends5implementsJava67Point,xy,init()xyclassPonit{intx,y;voidinit(intix,intiy){x=ix;y=iy;}}:private,protected,public,friendly1.8.2,,(),:1.8.3:1.typenametypenameDatetodayRectanglemyRectangle;todayDatemyRectangleRectangle2.referencetypeobjectName=newtype([paramlist]);new,new,()new3,Rectangle,Rectangle:Rectanglep1=newRectangle();Rectanglep2=newRectangle(3040);Rectanglep1p2,p1()p2p1p2,newCC++,,1.8.4,·,()PointclassPoint{intx,y;Stringname=apoint;Point(){x=0;y=0;}Point(intx,inty,Stringname){this.x=x;this.y=y;this.name=name;}intgetX(){returnx;}intgetY(){returny;}voidmove(intnewX,intnewY){x=newX;y=newY;}PointnewPoint(Stringname){PointnewP=newPoint(-x,-y,name);returnnewP;}booleanequal(intx,inty){if(this.x==x&&this.y==y)returntrue;elsereturnfalse;}voidprint(){System.out.println(name+:x=+x+y=+y);}}publicclassUsingObject{publicstaticvoidmain(Stringargs[]){Pointp=newPoint();p.print();//callmethodofanobjectp.move(50,50);System.out.println(**aftermoving**);System.out.println(Getxandydirectly);System.out.println(x=+p.x+y=+p.y);//accessvariablesofanob