将C转换为Java理解C中的宏

我被告知以下C代码

#define ADD(a, b) a + b

// example function
void foo()
{
  int i = ADD(1, 2); // add two ints
  double d = //doubles
    ADD(3.4, 5.6);

  int sly = ADD(1, 2) * 3; // not what it appears to be
}

转换为此Java代码

package demo;

public class DemoTranslation {
    public static int add(int a, int b) {
        return a + b;
    }

    public static double add(double a, double b) {
        return a + b;
    }

    /**
     * example function
     */
    public static void foo() {
        int i = add(1, 2); // add two ints
        double d = /* doubles */ add(3.4, 5.6);

        int sly = 1 + 2 * 3; // not what it appears to be
    }
}

java=7中的1+2*3。C代码是如何产生那个而不是9的?