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Transactions

org.bitcoinkernel.Transactions

Transaction, input, output, outpoint, coin, txid, and spent-output types.

Transaction

public static class Transaction implements AutoCloseable {
    public Transaction(byte[] rawTransaction)
    public Transaction copy()
    public long countInputs()
    public long countOutputs()
    public TransactionInput getInput(long index)
    public TransactionOutput getOutput(long index)
    public Txid getTxid()
    public void close()
}

A deserialized Bitcoin transaction. AutoCloseable.

Constructor:

Parameter Description
rawTransaction Raw consensus-serialized transaction bytes. Must be non-null and non-empty.

Throws IllegalArgumentException if the bytes are null, empty, or cannot be deserialized.

Methods:

Method Returns Description
copy() Transaction (owned) Deep copy. Caller must close.
countInputs() long Number of inputs.
countOutputs() long Number of outputs.
getInput(long) TransactionInput (view) Input at index (non-owned, do not close).
getOutput(long) TransactionOutput (view) Output at index (non-owned, do not close).
getTxid() Txid (view) Transaction ID (non-owned, do not close).

Example:

try (Transaction tx = new Transaction(rawTxBytes)) {
    System.out.println("Inputs:  " + tx.countInputs());
    System.out.println("Outputs: " + tx.countOutputs());
    System.out.println("Txid:    " + bytesToHex(tx.getTxid().toBytes()));
}

TransactionInput

public static class TransactionInput implements AutoCloseable {
    public TransactionInput copy()
    public TransactionOutPoint getOutPoint()
    public void close() throws Exception
}

A single transaction input. Obtained as a non-owned view from Transaction.getInput().

Methods:

Method Returns Description
copy() TransactionInput (owned) Deep copy. Caller must close.
getOutPoint() TransactionOutPoint The outpoint being spent (non-owned view).

Note

Inputs returned from Transaction.getInput() are non-owned views. Only close inputs obtained via copy().

TransactionOutPoint

public static class TransactionOutPoint implements AutoCloseable {
    public TransactionOutPoint copy()
    public long getIndex()
    public Txid getTxid()
    public void close() throws Exception
}

Identifies a specific output of a previous transaction (txid + vout index).

Methods:

Method Returns Description
copy() TransactionOutPoint (owned) Deep copy. Caller must close.
getIndex() long Output index (vout), as unsigned 32-bit value.
getTxid() Txid The referenced transaction ID (non-owned view).

TransactionOutput

public static class TransactionOutput implements AutoCloseable {
    public TransactionOutput(ScriptPubkey scriptPubkey, long amount)
    public TransactionOutput copy()
    public long getAmount()
    public ScriptPubkey getScriptPubKey()
    public void close()
}

A transaction output — an amount and a locking script. Can be constructed directly or obtained as a view.

Constructor:

Parameter Description
scriptPubkey The locking script.
amount Value in satoshis.

Methods:

Method Returns Description
copy() TransactionOutput (owned) Deep copy. Caller must close.
getAmount() long Amount in satoshis.
getScriptPubKey() ScriptPubkey (view) Non-owned view of the locking script. Do not close.

Coin

public static class Coin implements AutoCloseable {
    public long getConfirmationHeight()
    public boolean isCoinbase()
    public TransactionOutput getOutput()
    public Coin copy()
    public void close() throws Exception
}

A UTXO (unspent transaction output) with metadata. Obtained from TransactionSpentOutputs.getCoin().

Methods:

Method Returns Description
getConfirmationHeight() long Block height at which this coin was created (unsigned 32-bit).
isCoinbase() boolean Whether this output comes from a coinbase transaction.
getOutput() TransactionOutput (view) The underlying output. Non-owned; do not close.
copy() Coin (owned) Deep copy. Caller must close.

Txid

public static class Txid implements AutoCloseable {
    public Txid copy()
    public byte[] toBytes()
    public boolean equals(Txid other)
    public void close() throws Exception
}

A 32-byte transaction identifier. Usually obtained as a non-owned view from Transaction.getTxid() or TransactionOutPoint.getTxid().

Methods:

Method Returns Description
copy() Txid (owned) Deep copy. Caller must close.
toBytes() byte[32] Raw txid bytes.
equals(Txid) boolean Byte-level equality.

Note

Txid objects returned as views (from getTxid()) must not be closed. Only close instances obtained via copy().

TransactionSpentOutputs

public static class TransactionSpentOutputs implements Iterable<Coin> {
    public long count()
    public Coin getCoin(long index)
    public TransactionSpentOutputs copy()
    public Iterator<Coin> iterator()
    public void close()
}

The set of coins spent by a single non-coinbase transaction. Obtained from BlockSpentOutputs.getTransactionSpentOutputs().

Methods:

Method Returns Description
count() long Number of spent coins (equals the number of inputs).
getCoin(long) Coin (view) Coin at index i. Non-owned; do not close.
copy() TransactionSpentOutputs (owned) Deep copy. Caller must close.
iterator() Iterator<Coin> Iterate all spent coins.

Example — iterate undo data:

try (BlockSpentOutputs undoData = csm.readBlockSpentOutputs(entry)) {
    if (undoData == null) return;
    for (TransactionSpentOutputs txSpent : undoData) {
        for (Coin coin : txSpent) {
            System.out.println("  amount: " + coin.getOutput().getAmount());
        }
    }
}