java基本数据类型

public class TestDataType {

    public static void main(String[] args) {
        //byte,short,int ,long都可以用十进制、8进制，16进制。前缀0表示8进制，前缀0x表示16进制
        testType();
        stringCharTest();
        floatDoubleTest();
        automaticTypeTransform();
    }

    public static void testType() {
        int decimal = 100;
        int octal = 0144;
        int hh = 0x64;
        System.out.println(decimal + "----" + octal + "------" + hh);
        byte a = 16;
        byte b = 020;
        byte c = 0x10;
        System.out.println(a + "--" + b + "---" + c + "--");

        short x = 16;
        short y = 020;
        short z = 0x10;
        System.out.println(x + "--" + y + "---" + z + "--");

        long e = 16;
        long f = 020;
        long g = 0x10;
        System.out.println(e + "--" + f + "---" + g + "--");
    }

    public static void stringCharTest() {
        char c = '\u0001';
        String a = "\u0001";
        System.out.println(c + "---" + a);
        String b = "\\";
        char b1 = '\\';
        char d1 = '\'';
        String d = "\'";
        String x1 = "\t";
        char x = '\t';
        System.out.println(b + "--" + b1 + "---" + d1 + "--" + d + "  " + x1 + "--" + x);
    }

    public static void automaticTypeTransform() {
        //不能对boolean类型进行类型转换
        boolean f = true;
        Integer a = 1;
        String s = String.valueOf(a);
        //自动转换 是 byte,short,char->int->long->float->double，反过来需要强制类型转换
        char c1 = 'a';
        int i1 = c1;
        System.out.println("char自动类型转换为int后的值等于：" + i1);
        char c2 = 'A';
        int i2 = c2 + 1;
        System.out.println("char自动类型转换为int后的值等于：" + i2);
        int c = 2;
        long d = c;
        System.out.println("int自动类型转换为long后的值等于：" + d);
        char s1 = (char) c;
        System.out.println("int类型强制转换为char类型的值：" + s1);
        byte b1 = (byte) c;
        System.out.println("int类型强制转换为byte类型的值为：" + b1);
        //转换过程中可能会导致溢出或损失精度,因为byte类型是8未，最大值是127，当int型的i强制转换为byte类型时，值128就会导致溢出
        int i = 128;
        byte j = (byte) i;
        System.out.println(" int类型的i的值 " + i + "int类型的i强制转换为byte型的j 出现内存溢出 " + j);
    }

    public static void floatDoubleTest() {
        //浮点类型转换为整数是通过舍弃小数得到，而不是四舍五入
        float f = -45.79f;
        double d = 25.6;
        int a = (int) f;
        int b = (int) d;
        System.out.println(a + "   " + b);
    }


}

输出结果