Updated on 2026-08-14

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

@@ -0,0 +1,133 @@
+package org.stellar.sdk;
+
+import org.stellar.sdk.xdr.AccountID;
+import org.stellar.sdk.xdr.AllowTrustOp;
+import org.stellar.sdk.xdr.AssetType;
+import org.stellar.sdk.xdr.OperationType;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Represents <a href="https://www.stellar.org/developers/learn/concepts/list-of-operations.html#allow-trust" target="_blank">AllowTrust</a> operation.
+ * @see <a href="https://www.stellar.org/developers/learn/concepts/list-of-operations.html" target="_blank">List of Operations</a>
+ */
+public class AllowTrustOperation extends Operation {
+
+  private final KeyPair trustor;
+  private final String assetCode;
+  private final boolean authorize;
+
+  private AllowTrustOperation(KeyPair trustor, String assetCode, boolean authorize) {
+    this.trustor = checkNotNull(trustor, "trustor cannot be null");
+    this.assetCode = checkNotNull(assetCode, "assetCode cannot be null");
+    this.authorize = authorize;
+  }
+
+  /**
+   * The account of the recipient of the trustline.
+   */
+  public KeyPair getTrustor() {
+    return trustor;
+  }
+
+  /**
+   * The asset of the trustline the source account is authorizing. For example, if a gateway wants to allow another account to hold its USD credit, the type is USD.
+   */
+  public String getAssetCode() {
+    return assetCode;
+  }
+
+  /**
+   * Flag indicating whether the trustline is authorized.
+   */
+  public boolean getAuthorize() {
+    return authorize;
+  }
+
+  @Override
+  org.stellar.sdk.xdr.Operation.OperationBody toOperationBody() {
+    AllowTrustOp op = new AllowTrustOp();
+
+    // trustor
+    AccountID trustor = new AccountID();
+    trustor.setAccountID(this.trustor.getXdrPublicKey());
+    op.setTrustor(trustor);
+    // asset
+    AllowTrustOp.AllowTrustOpAsset asset = new AllowTrustOp.AllowTrustOpAsset();
+    if (assetCode.length() <= 4) {
+      asset.setDiscriminant(AssetType.ASSET_TYPE_CREDIT_ALPHANUM4);
+      asset.setAssetCode4(Util.paddedByteArray(assetCode, 4));
+    } else {
+      asset.setDiscriminant(AssetType.ASSET_TYPE_CREDIT_ALPHANUM12);
+      asset.setAssetCode12(Util.paddedByteArray(assetCode, 12));
+    }
+    op.setAsset(asset);
+    // authorize
+    op.setAuthorize(authorize);
+
+    org.stellar.sdk.xdr.Operation.OperationBody body = new org.stellar.sdk.xdr.Operation.OperationBody();
+    body.setDiscriminant(OperationType.ALLOW_TRUST);
+    body.setAllowTrustOp(op);
+    return body;
+  }
+
+  /**
+   * Builds AllowTrust operation.
+   * @see AllowTrustOperation
+   */
+  public static class Builder {
+    private final KeyPair trustor;
+    private final String assetCode;
+    private final boolean authorize;
+
+    private KeyPair mSourceAccount;
+
+    Builder(AllowTrustOp op) {
+      trustor = KeyPair.fromXdrPublicKey(op.getTrustor().getAccountID());
+      switch (op.getAsset().getDiscriminant()) {
+        case ASSET_TYPE_CREDIT_ALPHANUM4:
+          assetCode = new String(op.getAsset().getAssetCode4()).trim();
+          break;
+        case ASSET_TYPE_CREDIT_ALPHANUM12:
+          assetCode = new String(op.getAsset().getAssetCode12()).trim();
+          break;
+        default:
+          throw new RuntimeException("Unknown asset code");
+      }
+      authorize = op.getAuthorize();
+    }
+
+    /**
+     * Creates a new AllowTrust builder.
+     * @param trustor The account of the recipient of the trustline.
+     * @param assetCode The asset of the trustline the source account is authorizing. For example, if a gateway wants to allow another account to hold its USD credit, the type is USD.
+     * @param authorize Flag indicating whether the trustline is authorized.
+     */
+    public Builder(KeyPair trustor, String assetCode, boolean authorize) {
+      this.trustor = trustor;
+      this.assetCode = assetCode;
+      this.authorize = authorize;
+    }
+
+    /**
+     * Set source account of this operation
+     * @param sourceAccount Source account
+     * @return Builder object so you can chain methods.
+     */
+    public Builder setSourceAccount(KeyPair sourceAccount) {
+      mSourceAccount = sourceAccount;
+      return this;
+    }
+
+    /**
+     * Builds an operation
+     */
+    public AllowTrustOperation build() {
+      AllowTrustOperation operation = new AllowTrustOperation(trustor, assetCode, authorize);
+      if (mSourceAccount != null) {
+        operation.setSourceAccount(mSourceAccount);
+      }
+      return operation;
+    }
+  }
+}