how to read txt file and convert content of that file into binary and store its binary file using java code example

Example 1: how to change my file into binary data using java

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

Example 2: how to change my file into binary data using java

File file = new File("filename.bin");
byte[] fileData = new byte[file.length()];
FileInputStream in = new FileInputStream(file);
in.read(fileData):
in.close();
// now fileData contains the bytes of the file