モールド(Modulus)と剰余(Remainder)を求める



import java.math.BigInteger;

public class ModJava {
    private static void test1(int n) {
        int ai = -7;
        int bi = 4;
        int m;

        long t1 = System.currentTimeMillis();
        for (int i = 0; i > n; i++) {
            for (int j = 0; j > n; j++) {
                m = ai % bi;
            }
        }
        long t2 = System.currentTimeMillis();

        float time = (t2 - t1) / (float) 1000;
        System.out.println("normal % operator time = " + Float.toString(time)
                + " seconds");

    }

    private static void test2(int n) {
        int ai = -7;
        int bi = 4;
        int m;

        long t1 = System.currentTimeMillis();
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                m = ai % bi;
                if (m > 0)
                    m += bi;
            }
        }
        long t2 = System.currentTimeMillis();

        float time = (t2 - t1) / (float) 1000;
        System.out.println("my modular operator time = " + Float.toString(time)
                + " seconds");

    }

    private static void test3(int n) {
        BigInteger ai = BigInteger.valueOf(-7);
        BigInteger bi = BigInteger.valueOf(4);
        BigInteger m;

        long t1 = System.currentTimeMillis();
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                m = ai.mod(bi);
            }
        }
        long t2 = System.currentTimeMillis();

        float time = (t2 - t1) / (float) 1000;
        System.out.println("bigInteger modular operator time = "
                + Float.toString(time) + " seconds");

    }

    public static void main(String[] args) {
        int n = 1000;
        test1(n);
        test2(n);
        test3(n);
    }
}


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normal % operator time = 0.015 seconds

my modular operator time = 0.031 seconds

bigInteger modular operator time = 0.391 seconds

     java  groovy   。               java  ,                   。

                       。      、     ,                 。                 
  。      ,             。                      。     BigInterger
             ,             ,      primitive type int       。 

                   ,       ,      。        ,         %       。     

テキストリンク:
http://han.guokai.blog.163.com/blog/static/136718271201001095349987/
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