Java Utililty Methods CRC

java.util.zip.Adler32 inChecker = new java.util.zip.Adler32();
java.util.zip.CheckedInputStream in = null;
in = new java.util.zip.CheckedInputStream(new java.io.ByteArrayInputStream(tempStr.getBytes()), inChecker);
@SuppressWarnings("unused")
int c;
while ((c = in.read()) != -1)
    c = 0;
String myCheckSum = "" + inChecker.getValue();
...

CheckedInputStream cis = new CheckedInputStream(new BufferedInputStream(new FileInputStream(f)),
        new CRC32());
try {
    while (cis.read() != -1) {
    return cis.getChecksum().getValue();
} finally {
    cis.close();
...

byte[] buffer = new byte[4096];
CRC32 crc = new CRC32();
crc.reset();
int n = 0;
while (EOF != (n = input.read(buffer))) {
    crc.update(buffer, 0, n);
return crc.getValue();
...

if (data == null) {
    return -1;
try {
    byte bytes[] = data.getBytes("UTF-8");
    Checksum checksum = new CRC32();
    checksum.update(bytes, 0, bytes.length);
    return checksum.getValue();
...

CRC32 crc = new CRC32();
byte[] buffer = new byte[1024];
int length;
while ((length = stream.read(buffer)) != -1)
    crc.update(buffer, 0, length);
return crc.getValue();