Item 53: Use varargs judiciously

53. Variadic arguments should be used with caution

• When taking 0 or more arguments, the number of arguments may be checked and the result may not be beautiful. In such a case, the argument to be taken is decomposed into two as follows.

package tryAny.effectiveJava;

public class Varargs {
    public static void main(String[] args) {
        System.out.println(min1(99));
        System.out.println(min2(1, 2, 3));

    }

    // ugly
    static int min1(int... args) {
        if (args.length == 0)
            throw new IllegalArgumentException("Too few arguments");
        int min = args[0];
        for (int i = 1; i < args.length; i++)
            if (args[i] < min)
                min = args[i];
        return min;
    }

    // better
    static int min2(int firstArg, int... remainingArgs) {
        int min = firstArg;
        for (int arg : remainingArgs) {
            if (arg < min) {
                min = arg;
            }
        }
        return min;
    }
}

• When using variadic arguments, memory allocation and initialization of the array are required, which is costly. If you need to reduce the cost and know that the majority of cases have 3 or less arguments, create a case with 0,1,2,3 arguments in advance. Is good.

public void foo() { }
public void foo(int a1) { }
public void foo(int a1, int a2) { }
public void foo(int a1, int a2, int a3) { }
public void foo(int a1, int a2, int a3, int... rest) { }