io复制文件的时候为什么判断是不是到文件末尾都用temp = r.read(buf)) != -1 来判断啊
byte[] buf = new byte[1024];
int len = 0;
while((len = i.read(buf)) != -1) {
System.out.println(new String(buf,0,len));
}
char[] buf = new char[1024];
int temp = 0;
while((temp = r.read(buf)) != -1) {
System.out.print(new String(buf,0,temp));
}
为啥 判断是不是到文件结尾判断是否等于-1啊