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copied!<p>Depending on where you get those 4 bytes from:</p> <p><a href="http://docs.oracle.com/javase/7/docs/api/java/io/DataInput.html#readInt()" rel="nofollow noreferrer">http://docs.oracle.com/javase/7/docs/api/java/io/DataInput.html#readInt()</a></p> <p><a href="http://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#getInt(int)" rel="nofollow noreferrer">http://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#getInt(int)</a></p> <p>You can of course still do it manually, but in most cases using one of those (if you have to convert a byte array with lots of bytes, you might want to use a <code>DataInputStream</code> around a <code>ByteArrayInputStream</code> for example) is easier.</p> <p><strong>Edit</strong>: If you need to change the endianness, you will have to use a ByteBuffer, or reverse the bytes yourself, or do the conversion yourself, as DataInput does not support changing the endianness.</p> <p><strong>Edit2</strong>: When you get them from the socket input stream, I'd wrap that one into a <code>DataInputStream</code> and use it for reading all kinds of data. Especially since InputStream.read(byte[]) will not guarantee to fill the whole byte array... DataInputStream.readFully does.</p> <pre><code>DataInputStream in = new DataInputStream(socket.getInputStream()); byte aByte = in.readByte(); int anInt = in.readInt(); int anotherInt = in.readInt(); short andAShort = in.readShort(); // 11 bytes read :-) byte[] lotOfBytes = new byte[anInt]; in.readFully(lotOfBytes); </code></pre> <p><strong>Edit3</strong>: When reading multiple times from a stream, they will continue reading where you stopped, i. e. aByte will be byte 0, anInt will be bytes 1 to 4, anotherInt will be bytes 5 to 8, etc. readFully will read on after all that and will block until it has read <code>lotOfbytes</code>.</p> <p>When the stream stops (the connection drops) you will get <code>EOFException</code> instead of -1, so if you get -1, the int really was -1.</p> <p>If you do not want to parse any bytes at all, you can skip() them. Parsing one byte in 2 different ways is not possible with DataInputStream (i. e. read first an int from byte 0 to 3, then one from byte 2 to 5), but usually not needed either.</p> <p>Example:</p> <pre><code>// read messages (length + data) until the stream ends: while (true) { int messageLength; try { messageLength = in.readInt(); // bytes 0 to 3 } catch (EOFException ex) { // connection dropped, so handle it, for example return; } byte[] message = new byte[messageLength]; in.readFully(message); // do something with the message. } // all messages handled. </code></pre> <p>Hope this answers your additional questions.</p>

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