java:内存处理ByteArrayOutputStream,ByteArrayInputStream

//用内存，将小写字母替换成大写字母
String str = "helloworld,goodmorning";
ByteArrayOutputStream bos = null;
ByteArrayInputStream bis = null;
bis = new ByteArrayInputStream(str.getBytes());
bos = new ByteArrayOutputStream();
int temp = -1;
while( (temp = bis.read()) != -1 ) //依次读取内存
{
//接收字符
char c = (char) temp;
bos.write(Character.toUpperCase(c)); //输出
}
//取出内存中的内容
String newStr = bos.toString();
System.out.println(newStr);