user78: Blockchain.info has a PushTX API.
How do I create & sign a raw transaction in Java for use in this API?
Should I use bitcoinj?
Are there any code samples?

user888: Mike Hearn's WalletTool (included in the bitcoinj library) is a pretty good starting point.
If you have a look at the 'send' method in WalletTool you can see that it:
1) Creates a SendRequest
2) Decrypts the private key if necessary
3) Completes the tx to get the inputs and find the fee
4) Signs the tx
5) Starts up a PeerGroup
6) Broadcasts it
For an offline transaction you can do 1 to 4, serialize the tx and then call the blockchain pushtx.
There is a method on Transaction called bitcoinSerialize to convert it to the bytes that need transmitting. I think you just have to convert the bytes to hex for the blockchain pushtx but you would have to try it out.

user4960: Check out https://github.com/ValleZ/Paper-Wallet - it is android lite project what does this task. Start with createTransaction method in https://github.com/ValleZ/Paper-Wallet/blob/master/app/src/main/java/ru/valle/btc/BTCUtils.java

78: <p>Blockchain.info has a <a href="http://blockchain.info/pushtx" rel="noreferrer">PushTX API</a>.</p>

<p>How do I create &amp; sign a raw transaction in Java for use in this API?
Should I use bitcoinj?</p>

<p>Are there any code samples?</p>
 888: <p>Mike Hearn's WalletTool (included in the bitcoinj library) is a pretty good starting point.</p>

<p>If you have a look at the 'send' method in WalletTool you can see that it:</p>

<p>1) Creates a SendRequest</p>

<p>2) Decrypts the private key if necessary</p>

<p>3) Completes the tx to get the inputs and find the fee</p>

<p>4) Signs the tx</p>

<p>5) Starts up a PeerGroup</p>

<p>6) Broadcasts it</p>

<p>For an offline transaction you can do 1 to 4, serialize the tx and then call the blockchain pushtx.</p>

<p>There is a method on Transaction called bitcoinSerialize to convert it to the bytes that need transmitting. I think you just have to convert the bytes to hex for the blockchain pushtx but you would have to try it out.</p>
 4960: <p>Check out <a href="https://github.com/ValleZ/Paper-Wallet" rel="nofollow noreferrer">https://github.com/ValleZ/Paper-Wallet</a> - it is android lite project what does this task. Start with createTransaction method in <a href="https://github.com/ValleZ/Paper-Wallet/blob/master/app/src/main/java/ru/valle/btc/BTCUtils.java" rel="nofollow noreferrer">https://github.com/ValleZ/Paper-Wallet/blob/master/app/src/main/java/ru/valle/btc/BTCUtils.java</a></p>
