public class TestConvert {
    public static void main(String arg[]) {
        int i1 = 123;
        int i2 = 456;
        double d1 = (i1+i2)*1.2;
        float f1 = (float)((i1+i2)*1.2);
        byte b1 = 67;
        byte b2 = 89;
        byte b3 = (byte)(b1+b2);
红色加粗的数据类型是什么啊？为什么呢？