Java Class Methods - W3Schools

Access Methods With an Object · 1) We created a custom Main class with the class keyword. · 2) We created the fullThrottle() and speed() methods in the Main class ... 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throws try void while JavaStringMethods JavaMathMethods JavaExamples JavaExamples JavaCompiler JavaExercises JavaQuiz JavaCertificate JavaClassMethods ❮Previous Next❯ JavaClassMethods YoulearnedfromtheJavaMethodschapterthatmethodsaredeclaredwithina class,andthattheyareusedtoperformcertainactions: Example Createa methodnamedmyMethod()inMain: publicclassMain{  staticvoidmyMethod(){    System.out.println("HelloWorld!");  } } myMethod()printsatext(theaction),whenitis called.To callamethod,writethemethod'snamefollowedbytwoparentheses()andasemicolon; Example Insidemain,call myMethod(): publicclassMain{  staticvoidmyMethod(){    System.out.println("HelloWorld!");  }  publicstaticvoidmain(String[]args){    myMethod();  } } //Outputs"HelloWorld!" TryitYourself» Staticvs.Public YouwilloftenseeJavaprogramsthathaveeitherstaticorpublic attributesandmethods. Intheexampleabove,wecreatedastatic method,whichmeansthatitcanbeaccessedwithoutcreatinganobjectoftheclass, unlikepublic,whichcanonlybeaccessedby objects: Example Anexampletodemonstratethedifferencesbetweenstaticandpublic methods: publicclassMain{  //Staticmethod  staticvoidmyStaticMethod(){    System.out.println("Staticmethodscanbecalledwithoutcreatingobjects");  }  //Publicmethod  publicvoidmyPublicMethod(){    System.out.println("Publicmethodsmustbecalledbycreatingobjects");  }  //Mainmethod  publicstaticvoidmain(String[]args){    myStaticMethod();//Callthestaticmethod    //myPublicMethod();Thiswouldcompileanerror    MainmyObj=newMain();//CreateanobjectofMain    myObj.myPublicMethod();//Callthepublicmethodontheobject  } } TryitYourself» Note:Youwilllearnmoreaboutthesekeywords(calledmodifiers)intheJavaModifierschapter. AccessMethodsWithanObject Example CreateaCarobjectnamedmyCar.CallthefullThrottle()andspeed() methodsonthemyCarobject,andruntheprogram: //CreateaMainclass publicclassMain{    //CreateafullThrottle()method  publicvoidfullThrottle(){    System.out.println("Thecarisgoingasfastasitcan!");  }  //Createaspeed()methodandaddaparameter  publicvoidspeed(intmaxSpeed){    System.out.println("Maxspeedis:"+maxSpeed);  }  //Insidemain,callthemethodsonthemyCarobject  publicstaticvoidmain(String[]args){    MainmyCar=newMain();  //CreateamyCarobject    myCar.fullThrottle();     //CallthefullThrottle()method    myCar.speed(200);        //Callthespeed()method  } } //Thecarisgoingasfastasitcan! //Maxspeedis:200 TryitYourself» Exampleexplained 1)WecreatedacustomMainclasswiththeclasskeyword. 2)WecreatedthefullThrottle()and speed() methodsintheMainclass. 3)ThefullThrottle()methodandthe speed() methodwillprintoutsometext,whentheyarecalled. 4)Thespeed() methodacceptsanintparametercalled maxSpeed-we willusethisin8). 5)InordertousetheMainclassandits methods,weneedtocreateanobjectofthe MainClass. 6)Then,gotothemain()method,whichyouknowbynowisabuilt-in Javamethodthatrunsyourprogram(anycodeinsidemainisexecuted). 7)Byusingthenewkeywordwecreatedanobjectwiththename myCar. 8)Then,wecallthefullThrottle()and speed() methodsonthe myCarobject,andruntheprogramusingthenameoftheobject(myCar),followedbyadot(.),followedbythenameofthemethod(fullThrottle();and speed(200);). Noticethatweaddanintparameterof200insidethe speed()method. Rememberthat.. Thedot(.)isusedtoaccesstheobject'sattributesandmethods. TocallamethodinJava,writethemethodnamefollowedbyasetofparentheses(),followedbyasemicolon(;). Aclassmusthaveamatchingfilename(Mainand Main.java). UsingMultipleClasses LikewespecifiedintheClasseschapter,itis agoodpracticetocreateanobjectofaclassandaccessitinanotherclass. Rememberthatthenameofthejavafileshouldmatchtheclassname.Inthis example,wehavecreatedtwofilesinthesamedirectory: Main.java Second.java Main.java publicclassMain{  publicvoidfullThrottle(){    System.out.println("Thecarisgoingasfastasitcan!");  }  publicvoidspeed(intmaxSpeed){    System.out.println("Maxspeedis:"+maxSpeed);  } } Second.java classSecond{  publicstaticvoidmain(String[]args){    MainmyCar=newMain();    //CreateamyCarobject    myCar.fullThrottle();      //CallthefullThrottle()method    myCar.speed(200);         //Callthespeed()method  } } Whenbothfileshavebeencompiled: C:\Users\YourName>javacMain.java C:\Users\YourName>javacSecond.java RuntheSecond.javafile: C:\Users\YourName>javaSecond Andtheoutputwillbe: Thecarisgoingasfastasitcan! Maxspeedis:200 TryitYourself» ❮Previous Next❯ NEW WejustlaunchedW3Schoolsvideos Explorenow COLORPICKER Getcertifiedbycompletingacoursetoday! w3schoolsCERTIFIED.2022 Getstarted CODEGAME PlayGame