方法快速入门教程day05

（Function参数返回值（Function参数返回值return返回值;publicstaticpublicclassDemo02MethodDefine数据类型变量名称=方法名称(参数值);publicstaticintsum(intaintbintresult=a+b;//方法体returnresult;publicstaticvoidmain(String[]args)修饰符void修饰符void返回值类型：固定为voidreturn：后面不能写返回值，直接分号结束。而且最后一行return通常情况下会省略不写publicclassDemo01MethodVoidpublicstaticvoidmain(String[]args)错误写法！void 错误写法！void intnum= intnum=publicclassDemo02PrintArraypublicclassDemo02PrintArraypublicstaticvoidmain(String[]args)1int[]array={10,20,30,40,50,65,753调用方法，传入参数数据（一个数组2publicstaticvoidprintHelloWorld()for(inti=0;i<10;i++){System.out.println("Hello,World!"+(i+1)); returnreturn return100错误写法！voidpublicstaticvoidprintHelloWorldCount(intcount)for(inti=0;i<count;i++){System.out.println("Hello,World!"+(i+1));publicclassDemo04VoidVsReturnpublicpublicclassDemo04VoidVsReturnpublicstaticvoidmain(String[]args)int[]array={1,2,7,12,80,-14intresult=publicclassDemo03PrintArrayFormatpublicstaticvoidmain(String[]args)int[]array1={10,20,30,40,50int[]array2={5,15,25,35,45publicstaticvoidprintArrayFormat(int[]array)System.out.print("[")1for(inti=0;i<array.length;i++)2if(iarray.length1System.out.println(array[i]+elseSystem.out.print(array[i]+",参数列表：一定要得到一个数组，才能打印。publicstaticvoidprintArray(int[]array)for(inti=0;i<array.length;i++){System.out.println("结果是：publicstaticintsumA(int[]array)intsum0for(inti=0;i<array.length;i++){sum+=array[i];returnpublicstaticvoidsumB(int[]array)intsum=for(inti=0;i<array.length;i++){sum+=array[i];System.out.println("总和：publicclasspublicclassDemo01MethodOverloadpublicstaticvoidmain(String[]args) System.out.println(sumTwo(10,20));// System.out.println(sumThree(10,20,30));// System.out.println(sumFour(10,20,30,40));//System.out.println(sum(10,20));//System.out.println(sum(10,20,30));//System.out.println(sum(10,20,30,40));// System.out.println(sum(10,20,30,40,50))错误的写法！因为没有System.out.println(sum(10,20));//intSystem.out.println(sum(10.5,20.5));//doubleSystem.out.println(sum(2.510))doubleintSystem.out.println(sum(102.5))intpublicstaticdoublesum(inta,doubleb){returnabpublicstaticdoublesum(doublea,intb){returnabpublicstaticdoublesum(doublea,doubleb){returna+b;publicstaticintsum(inta,intb){returna+b;实际参数对于基本类型（String）实际参数对于基本类型（String）对于引用类型（String）publicclassDemo01BasicParampublicstaticvoidmain(String[]args)inta=intb=System.out.println("a="+a);//10System.out.println("b="+b);////publicstaticintsum(intx,inty) returnx+////publicstaticdoublesum(inta,intb) returna+b+//publicstaticintsum(inta,intb,intc){returna+b+c;publicstaticintsum(intaintbintcintdSystem.out.println("4int参数的方法执行！");returna+b+c+d;publicclassDemo02RefParampublicclassDemo02RefParampublicstaticvoidmain(String[]args)int[]array={10,20,30System.out.println(array[0]);//System.out.println(array[1]);//System.out.println(array[2]);//30System.out.println(array[0]);//100System.out.println(array[1]);//System.out.println(array[2]);//publicstaticvoidchange(int[]arr){arr[0]*=10;arr[1]*=arr[2]*=System.out.println(arr[0]);//System.out.println(arr[1]);//System.out.println(arr[2]);//change(ab)System.out.println("a="+a);//10System.out.println("b="+b);//20p