DataReader.java - Convert Byte Array To Integer/Long/Float/Double

DataReader.java

package references;

import java.io.IOException;
import java.io.InputStream;

import android.util.Log;

abstract class DataReader {

	public static final int INVALID_DATA = -1;
	private InputStream dis = null;
	
	protected DataReader(InputStream is) {
		dis = is;
	}
	
	public abstract boolean read();
	
	protected float readFloat() {
		int value = readInt();
		if (value != INVALID_DATA) {
			return Float.intBitsToFloat(value);
		}
		return INVALID_DATA;
	}
	
	protected int readInt() {
		byte[] bytes = readBytes(4);
		if (bytes != null) {
			int value = 0;
			value += (bytes[3] & 0x000000FF) << 24;
			value += (bytes[2] & 0x000000FF) << 16;
			value += (bytes[1] & 0x000000FF) << 8;
			value += (bytes[0] & 0x000000FF);
			return value;
		}
		return INVALID_DATA;
	}
	
	protected double readDouble() {
		long value = readLong();
		if (value != INVALID_DATA) {
			return Double.longBitsToDouble(value);
		}
		return INVALID_DATA;
	}
	
	protected long readLong() {
		byte[] bytes = readBytes(8);
		if (bytes != null) {
			long value = 0;
			value += (long) (bytes[7] & 0x000000FF) << 56;
			value += (long) (bytes[6] & 0x000000FF) << 48;
			value += (long) (bytes[5] & 0x000000FF) << 40;
			value += (long) (bytes[4] & 0x000000FF) << 32;
			value += (bytes[3] & 0x000000FF) << 24;
			value += (bytes[2] & 0x000000FF) << 16;
			value += (bytes[1] & 0x000000FF) << 8;
			value += (bytes[0] & 0x000000FF);
			return value;
		}
		return INVALID_DATA;
	}
	
	protected void skipBytes(int length) {
		try {
			int count = (int) dis.skip(length);
			if (count != length) {
				Log.i("Incorrect Data Size (Intended:Actual): ",
					String.valueOf(length) + ":" + String.valueOf(count));
			}
		} catch (IOException ex) {
			Log.w("[email protected]()", ex);
		}
	}
	
	protected void readBytes(int length) {
		byte[] bytes = new byte[length];
		try {
			int count = dis.read(bytes, 0, length);
			if (count != length) {
				Log.i("Incorrect Data Size (Intended:Actual): ",
					String.valueOf(length) + ":" + String.valueOf(count));
				return null;
			}
			return bytes;
		} catch (IOException ex) {
			Log.w("[email protected]()", ex);
		}
		return null;
	}
}

Is the return type of the readBytes wrong? Its returns a bytes array on line 86, yet the return type is void.