byte类型如何转换成int类型?

[birditren2001]

下面是我写的一个测试程序,为什么两个print出来的不一样?应该是这行出了问题,
int rtime = ((time[0] << 24) + (time[1] << 16) + (time[2] << 8) + time[3]);
我该如何把byte类型如何转换成int类型?

import java.util.*;
public class HelloDate {
public static void main(String[] args) {
System.out.println("Hello, it's: ");
System.out.println(new Date());
java.text.SimpleDateFormat f=new java.text.SimpleDateFormat("MMddhhmmss");
java.util.Date d=new java.util.Date();
String stime = f.format(d);
System.out.println(stime);
int itime = Integer.parseInt(stime) ;
byte time[] = new byte[1024*3] ;
System.arraycopy(int2byte(itime),0,time,0,4) ;
int rtime = ((time[0] << 24) + (time[1] << 16) + (time[2] << 8) + time[3]);
System.out.println(rtime) ;
}
private static byte[] int2byte(int n)
{
byte b[] = new byte[4];
b[0] = (byte)(n >> 24);
b[1] = (byte)(n >> 16);
b[2] = (byte)(n >> 8);
b[3] = (byte)n;
return b;
}

}

[hyhu]

byte的intValue()可返回int值！！

[buzhiming99]

public class Converter {

public static byte[] toByteArray(int number)
{
int temp = number;
byte[] b=new byte[4];
for (int i = b.length - 1; i > -1; i--)
{
b[i] = new Integer(temp & 0xff).byteValue();
temp = temp >> 8;
}
return b;
}

public static int toInteger(byte[] b)
{
int s = 0;
for (int i = 0; i < 3; i++)
{
if (b[i] >= 0)
s = s + b[i];
else
s = s + 256 + b[i];
s = s * 256;
}
if (b[3] >= 0)
s = s + b[3];
else
s = s + 256 + b[3];
return s;
}
}

[birditren2001]

可是我的int数值被打成4个byte来存放的,我要如何组织成原来的int数值?

[hyhu]

（（千位*10+百位）*10+十位）*10+个位

[cbhyk]

int rtime = (((time[0]&0xff) << 24) + ((time[1]&0xff) << 16) + ((time[2]&0xff) << 8) + time[3]&0xff);

[birditren2001]

int rtime = (((time[0]&0xff) << 24) + ((time[1]&0xff) << 16) + ((time[2]&0xff) << 8) + time[3]&0xff);
这个好像不对,不信楼上的大哥测试一下看看.

[cbhyk]

应该这样写：
int rtime = ((time[0]&0xff) << 24) + ((time[1]&0xff) << 16) + ((time[2]&0xff) << 8) + (time[3]&0xff);