关于强制转化的问题

package com.xiaoa.demo;

public class Convert {
    public static void main(String[] args) {
        int i = 1, j = 1, i1, i2;
        float f1 = 0.1f;
        float f2 = 123;
        long l1 = 12345678, l2 = 8888888888l;
        double d1 = 2e20, d2 = 124;
        byte b1 = 1, b2 = 2, b3 = 127;
        j = j + 10;
        i1 = i / 10;
        i2 = (int) (i * 0.1);
        char c1 = 'a', c2 = 125;
        byte b = (byte) (b1 - b2);
        char c = (char) (c1 + c2 - 1);
        float f3 = f1 + f2;
        float f4 = (float) (f1 + f2 * 0.1);
        double d = d1 * i + j;
        float f = (float) (d1 * 5 + d2);
        System.out.println("j=" + j);
        System.out.println("i1=" + i1);
        System.out.println("i2=" + i2);
        System.out.println("b=" + b);
        System.out.println(c1 + c2 -1);
        //因为char的字符范围(-127~128)内找不到221,所以用?代替了
        System.out.println((char)(126));
        System.out.println((char)(127));
        System.out.println((char)(128));
        System.out.println("c=" + c);
        System.out.println("f3=" + f3);
        System.out.println("f4=" + f4);
        System.out.println("d=" + d);
        System.out.println("f=" + f);
    }
}