Catalogue：

I.Preface :

II.Syntax :

III.NOTICE(significant) :

IV.Code Demonstrate :

       1.Show notice one, notice two and notice three :

       2.Show notice four :

       3.Show notice five :

       4.Exercise:

I.Preface :

       java allows us to encapsulate many methodswhich have the same name and function but have different number of parametersinto one method  at one class.

       We achieve it by using variable parameter in the list of formal parameters.

       By the way, we will use variable parameter in the module java reflect, etc.

II.Syntax :

       access_modifierreturn_typemethod_name (data_structures... parameters) {

   

       }

       ΔIn the list of formal parameters, the format of three points "..." is fix.

III.NOTICE(significant) :

       1. The number of actual parameter can range from 0 to n.(n = 1, 2, 3, 4, 5......)

       2. The actual parameter can be an array directly.

       3. The variable parameter is actually an array, so you can use it as an array.

       4. When variable parameter is used with ordinary parameter, make sure that the             variable parameter is at last of the list of formal parameter.

       5. There could be only one variable parameter at one parameter list.

IV.Code Demonstrate :

       Hey, guys, I am about to demonstrate all the notices mentioned above in code.

       1.Show notice one, notice two and notice three :

packagecsdn.varparameter;
publicclassVariableParameter {
publicstaticvoidmain(String[] args) {
Test1t1=newTest1();
int[] array1= {2, 11, 211, 985, 141};
//1. The number of actual parameter can range from 0 to n.(n = 1, 2, 3, 4, 5......)System.out.println(t1.getSum(0, 1, 2, 3, 4, 5));
System.out.println(t1.getSum(array1));
//2. The actual parameter can be an array directly.System.out.println("------------------------");
    }
}
classTest1 {
publicintgetSum(int... parameters) {
System.out.println(parameters.length+" parameters were received.");
//3. The variable parameter is actually an array, so you can use it as an array.intnum=0;
for (inti=0; i<parameters.length; ++i) {
num+=parameters[i];
        }
System.out.print("The Sum of parameters passed is : ");
returnnum;
    }
}

       Output result :

       2.Show notice four :

packagecsdn.varparameter;
publicclassVariableParameter {
publicstaticvoidmain(String[] args) {
Test2t2=newTest2();
int[] array1= {2, 11, 211, 985, 141};
int[] array2= {1, 2, 7};
System.out.println(t2.getSum2(array1, 1, 3, 1));
System.out.println(t2.getSum2(array1, array2));
System.out.println("------------------------");
    }
}
/*4. When variable parameter is used with ordinary parameter, make sure that the variable parameter is at last of the list of formal parameter.*/classTest2 {
publicintgetSum2(int[] arr, int... parameters) {
System.out.println(parameters.length+" parameters were received.");
intsum1=0;
intsum2=0;
for (inti=0; i<arr.length; ++i) {
sum1+=arr[i];
        }   //Use sum1 variable to store the sum of "arr" array.for (inti=0; i<parameters.length; ++i) {
sum2+=parameters[i];
        }   //Use sum2 variable to store the sum of "variable parameter".System.out.print("The total sum of parameters passed is : ");
returnsum1+sum2;
    }
}

       Output result :

       3.Show notice five :

        Actually it's easy to understand the notice five, because we have got the notice four :  When variable parameter is used with ordinary parameter, make sure that the variable parameter is at last of the list of formal parameter. So, if you have variable parameters, more than one, you can't promise that every variable parameters is at the end of the the list of formal parameters. Absolutely you can't achieve it!

       Let's have a look at the demonstration，a GIF picture, as follow:

       Apparently, we can see the IDEA report a error, and the reason is actually what we're talking about above.        

       4.Exercise:

      requirement : Encapsulate one static method in a arbitrary class, whatever, and the formal parameters you need to pass in are Student's name, Student's grade and the scores of his or her every subjects.We supposed that the Student totally examines five subject. When this method is invoked, the student's name, grade and five subjects' sum scores will be printed on the console.

       Code Demonstration :

packagecsdn.varparameter;
publicclassVariableParameter {
publicstaticvoidmain(String[] args) {
System.out.println(Test3.studentScore("Cyan", 14, 141,135,80,75));
    }
}
classTest3 {
publicstaticStringstudentScore(Stringname, intgrade, int... scores) {
intscoreNum=0;
for (inti=0; i<scores.length; ++i) {
scoreNum+=scores[i];
        }
returnname+", who is in "+grade+" class, got totally "+scoreNum+" points";
    }
}

       Output result :

System.out.println("END---------------------------------------------------------------------");