方法重载null参数

Question

In my code, I have a method which has got to take 4 parameters. But in somewhere in the code i call this method with sometimes 2, sometimes 4 parameters. So when i call with 2 parameters, the last 2 parameters should go automaticly null.

For example:

public static void x(String one,String two,String three=null,String four=null){

//do something hear

}

x("one","two");
x("one","two","three","four");

When I call x("one","two") => I want that the three and four parameters automatticaly initialize to null.

How can i do that ? Thanks for helps.

Answer 1

class A{

   public void do(String a, String b, String c, String d){
        //do something
   }

   //Overload do method
   public void do(String a, String b){
        do(a,b,null,null);
   }
}

Answer 2

Best option is to keep your method with 4 parameters only, just when you need to pass only 2 parameters, pass the other 2 parameters as null.

For Example for 2 params pass:

    x(a,b,null,null);

and for 4 params pass:

    x(a,b,c,d);

Answer 3

This works as well and can be called using an Array of Strings as parameter, or multiple comma separated Strings. This way you don't have to overload.

public void myMethod(String ...strings)  {
    for (String string : strings) {
        //do something with the string
    }
}

you can call it using an array:

myMethod(new String[]{"test1", "test2"})

or several Strings:

myMethod("test1", "test2");
myMethod("test1", "test2", "test3", "test4");