how to change my file into binary data using java

1File file = new File("filename.bin");
2byte[] fileData = new byte[file.length()];
3FileInputStream in = new FileInputStream(file);
4in.read(fileData):
5in.close();
6// now fileData contains the bytes of the file
7

1String content = "";
2for(byte b : fileData)
3    content += getBits(b);
4// content now contains your bits.
5

1String getBits(byte b)
2{
3    String result = "";
4    for(int i = 0; i < 8; i++)
5        result += (b & (1 << i)) == 0 ? "0" : "1";
6    return result;
7}
8