FileChannel: size()
import java.io.FileInputStream; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.FileChannel; public class MainClass { public static void main(String args[]) { FileInputStream fIn; FileChannel fChan; long fSize; ByteBuffer mBuf; try { fIn = new FileInputStream("test.txt"); fChan = fIn.getChannel(); fSize = fChan.size(); mBuf = ByteBuffer.allocate((int) fSize); fChan.read(mBuf); mBuf.rewind(); for (int i = 0; i < fSize; i++) System.out.print((char) mBuf.get()); fChan.close(); fIn.close(); } catch (IOException exc) { System.out.println(exc); } } }