Implementation:Microsoft Onnxruntime OnnxSequence

Knowledge Sources	Description
Source File	java/src/main/java/ai/onnxruntime/OnnxSequence.java
Repository	Microsoft/onnxruntime

Domains

• Machine Learning Runtime
• Sequence Value Container
• JNI Native Interop

Overview

OnnxSequence represents a sequence of OnnxValue elements, all of the same type. It wraps a native ORT sequence value and can contain either a list of OnnxTensor objects (for String, Long, Float, or Double element types) or a list of OnnxMap objects (for map sequences). The class implements the OnnxValue interface.

Description

The class provides:

• Value extraction: getValue() returns an unmodifiable List<? extends OnnxValue>. For map sequences, it calls the native getMaps method; for tensor sequences, it calls getTensors. Unlike other OnnxValue.getValue() methods, this does not copy data to the Java heap -- it exposes native values as OnnxValue instances. The returned elements must be closed separately from the sequence.
• Type info: getInfo() returns the SequenceInfo describing the element type.
• Supported tensor element types: STRING, INT64, FLOAT, DOUBLE.
• Supported map types: Map<String, Float> and Map<Long, Float>.
• Lifecycle: close() releases the native sequence; isClosed() checks state.

Code Reference

Source Location

// File: java/src/main/java/ai/onnxruntime/OnnxSequence.java
// Package: ai.onnxruntime

Signature

public class OnnxSequence implements OnnxValue {
    public OnnxValueType getType();   // returns ONNX_TYPE_SEQUENCE
    public List<? extends OnnxValue> getValue() throws OrtException;
    public SequenceInfo getInfo();
    public synchronized boolean isClosed();
    public synchronized void close();
}

Import

import ai.onnxruntime.OnnxSequence;

I/O Contract

Inputs

Name	Type	Description
nativeHandle	long	Pointer to the native ORT sequence value (set internally)
allocatorHandle	long	Pointer to the allocator
info	SequenceInfo	Type information about the sequence elements

Outputs

Name	Type	Description
getValue()	List<? extends OnnxValue>	Unmodifiable list of OnnxTensor or OnnxMap elements
getInfo()	SequenceInfo	Sequence element type metadata
getType()	OnnxValueType	Always ONNX_TYPE_SEQUENCE

Usage Examples

import ai.onnxruntime.*;
import java.util.*;

OrtEnvironment env = OrtEnvironment.getEnvironment();
try (OrtSession session = env.createSession("/path/to/model.onnx")) {
    Map<String, OnnxTensorLike> inputs = new HashMap<>();
    // ... prepare inputs ...

    try (OrtSession.Result results = session.run(inputs)) {
        OnnxValue output = results.get(0);
        if (output.getType() == OnnxValue.OnnxValueType.ONNX_TYPE_SEQUENCE) {
            OnnxSequence sequence = (OnnxSequence) output;
            List<? extends OnnxValue> elements = sequence.getValue();
            System.out.println("Sequence length: " + elements.size());

            for (OnnxValue element : elements) {
                if (element instanceof OnnxTensor) {
                    System.out.println("Tensor value: " + ((OnnxTensor) element).getValue());
                }
                element.close(); // Elements must be closed separately
            }
        }
    }
}

Related Pages

• SequenceInfo.java - Type metadata for OnnxSequence
• OnnxMap.java - Map type that can be contained in sequences
• OnnxTensor.java - Tensor type that can be contained in sequences
• OrtSession.java - Session that produces OnnxSequence outputs