import java.util.Random;

/**
 * Created by Kevin on 11/1/16.
 */
public class math {
    static void prt(String s){

        System.out.println(s);
    }

    static  void pInt(String s, int i){
        prt(s + " = " + i);
    }

    static  void pFlt(String s, float f){

        prt(s + " = " + f);
    }

    public static void main(String[] args){
        Random rand = new Random();
        int i, j, k;

        j = rand.nextInt() % 100;
        k = rand.nextInt() % 100;
        pInt("j", j);
        pInt("k", k);
        i = j + k; pInt("j + k", i);
        i = j - k; pInt("j - k", i);
        i = k / j; pInt("k / j", i);
        i = k * j; pInt("k * j", i);
        i = k % j; pInt("k % j", i);
        j %= k; pInt("j %= k", j);

        //Floating-point number tests
        float u, v, w;
        v = rand.nextFloat();
        w = rand.nextFloat();
        pFlt("v", v); pFlt("w", w);
        u = v + w; pFlt("v + w", u);
        u = v - w; pFlt("v - w", u);
        u = v * w; pFlt("v * w", u);
        u = v / w; pFlt("v / w", u);

        u += v; pFlt("u += v", u);
        u -= v; pFlt("u -= v", u);
        u *= v; pFlt("u *= v", u);
        u /= v; pFlt("u /= v", u);

        //for loop
        System.out.println("For Loop Example:");
        for(char c = 0; c < 128; c++){
            if (c != 26)
                System.out.println("value: " + (int)c + " character: " + c);
        }

        for(int o = 0;o < 100; o++){
            if (o != 74) break;
            if (o % 9 != 0) continue;
            System.out.println(o);
        }

        int o = 0;

        while (true){
            o++;
            int p = o * 27;
            if (p == 1269) break;
            if(o % 10 != 0) continue;
            System.out.println(p);
        }
    }
}

不写注释了，应该很容易懂