用代码来测试JAVA中数据类型的存储大小

感谢CSDN jack_chen


import java.io.*;

public class abc {

    public static void main(String[] args) {

        char cr = 1;
        byte be = 1;
        short st = 1;
        int it = -1;
        long lg = 1;
        float ft = 1;
        double de = 1;

        int cnt;
        byte x;
        int cot = 0;
        int byteSize = 0;

        // System.out.println("Float.size: "+Float.SIZE);
        // System.out.println("Double.size: "+Double.SIZE);

        for (cnt = 1; (cr <<= 1) != 0; cnt++)
            ;
        System.out.println("char'sBits:" + cnt);

        for (cnt = 1; (be <<= 1) != 0; cnt++)
            ;
        System.out.println("byte'sBits:" + cnt);
        byteSize = cnt;

        for (cnt = 1; (st <<= 1) != 0; cnt++)
            ;
        System.out.println("short'sBits:" + cnt);

        for (cnt = 1; (it <<= 1) != 0; cnt++)
            ;
        System.out.println("int'sBits:" + cnt);

        for (cnt = 1; (lg <<= 1) != 0; cnt++)
            ;
        System.out.println("long'sBits:" + cnt);

        // 用字节流处理double
        try {
            ByteArrayOutputStream buf = new ByteArrayOutputStream();
            DataOutputStream out = new DataOutputStream(buf);
            out.writeDouble(de);
            out.close();
            DataInputStream in = new DataInputStream(new ByteArrayInputStream(
                    buf.toByteArray()));

            while ((x = (byte) in.readByte()) != -1) {

                // System.out.println("byte["+cot+"]:"+x);
                cot++;
            }
            in.close();

        } catch (IOException e) {
            System.out.println("EOF!!!");
        }
        System.out.println("The Double's bit size is :" + cot * byteSize);

        // 用字节流处理float
        try {
            cot = 0;
            ByteArrayOutputStream buf = new ByteArrayOutputStream();
            DataOutputStream out = new DataOutputStream(buf);
            out.writeFloat(ft);
            out.close();
            DataInputStream in = new DataInputStream(new ByteArrayInputStream(
                    buf.toByteArray()));

            while ((x = (byte) in.readByte()) != -1) {

                // System.out.println("byte["+cot+"]:"+x);
                cot++;
            }
            in.close();

        } catch (IOException e) {
            System.out.println("EOF!!!");
        }
        System.out.println("The Float's bit size is :" + cot * byteSize);

    }

}