Updated on 2026-08-14

app/src/main/java/org/stellar/sdk/Memo.java

@@ -0,0 +1,93 @@
+package org.stellar.sdk;
+
+import com.google.common.io.BaseEncoding;
+
+/**
+ * <p>The memo contains optional extra information. It is the responsibility of the client to interpret this value. Memos can be one of the following types:</p>
+ * <ul>
+ *  <li><code>MEMO_NONE</code>: Empty memo.</li>
+ *  <li><code>MEMO_TEXT</code>: A string up to 28-bytes long.</li>
+ *  <li><code>MEMO_ID</code>: A 64 bit unsigned integer.</li>
+ *  <li><code>MEMO_HASH</code>: A 32 byte hash.</li>
+ *  <li><code>MEMO_RETURN</code>: A 32 byte hash intended to be interpreted as the hash of the transaction the sender is refunding.</li>
+ * </ul>
+ * <p>Use static methods to generate any of above types.</p>
+ * @see Transaction
+ */
+public abstract class Memo {
+    /**
+     * Creates new MemoNone instance.
+     */
+    public static MemoNone none() {
+        return new MemoNone();
+    }
+
+    /**
+     * Creates new {@link MemoText} instance.
+     * @param text
+     */
+    public static MemoText text(String text) {
+        return new MemoText(text);
+    }
+
+    /**
+     * Creates new {@link MemoId} instance.
+     * @param id
+     */
+    public static MemoId id(long id) {
+        return new MemoId(id);
+    }
+
+    /**
+     * Creates new {@link MemoHash} instance from byte array.
+     * @param bytes
+     */
+    public static MemoHash hash(byte[] bytes) {
+        return new MemoHash(bytes);
+    }
+
+    /**
+     * Creates new {@link MemoHash} instance from hex-encoded string
+     * @param hexString
+     */
+    public static MemoHash hash(String hexString) {
+        return new MemoHash(hexString);
+    }
+
+    /**
+     * Creates new {@link MemoReturnHash} instance from byte array.
+     * @param bytes
+     */
+    public static MemoReturnHash returnHash(byte[] bytes) {
+        return new MemoReturnHash(bytes);
+    }
+
+    /**
+     * Creates new {@link MemoReturnHash} instance from hex-encoded string.
+     * @param hexString
+     */
+    public static MemoReturnHash returnHash(String hexString) {
+        // We change to lowercase because we want to decode both: upper cased and lower cased alphabets.
+        return new MemoReturnHash(BaseEncoding.base16().lowerCase().decode(hexString.toLowerCase()));
+    }
+
+    public static Memo fromXdr(org.stellar.sdk.xdr.Memo memo) {
+        switch (memo.getDiscriminant()) {
+            case MEMO_NONE:
+                return none();
+            case MEMO_ID:
+                return id(memo.getId().getUint64().longValue());
+            case MEMO_TEXT:
+                return text(memo.getText());
+            case MEMO_HASH:
+                return hash(memo.getHash().getHash());
+            case MEMO_RETURN:
+                return returnHash(memo.getRetHash().getHash());
+            default:
+                throw new RuntimeException("Unknown memo type");
+        }
+    }
+
+    abstract org.stellar.sdk.xdr.Memo toXdr();
+    abstract public boolean equals(Object o);
+}