Implementation:Microsoft Onnxruntime NNAPIFlags

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

Domains

• Machine Learning Runtime
• Execution Provider Configuration
• Android NNAPI

Overview

NNAPIFlags is a public enum providing bitwise flags for configuring the Android NNAPI (Neural Networks API) execution provider. It implements the OrtFlags interface, allowing flags to be combined into a bitmask via EnumSet.

Description

The enum defines four flags:

• USE_FP16 (1): Enables fp16 support for improved performance on devices with fp16 acceleration.
• USE_NCHW (2): Uses channels-first (NCHW) format. Only recommended for development and validation.
• CPU_DISABLED (4): Disables NNAPI CPU fallback. If an operator can only run on CPU via NNAPI, model load will fail.
• CPU_ONLY (8): Force NNAPI to use CPU only. Not recommended for production due to performance impact.

Code Reference

Source Location

// File: java/src/main/java/ai/onnxruntime/providers/NNAPIFlags.java
// Package: ai.onnxruntime.providers

Signature

public enum NNAPIFlags implements OrtFlags {
    USE_FP16(1), USE_NCHW(2), CPU_DISABLED(4), CPU_ONLY(8);

    public final int value;
    public int getValue();
}

Import

import ai.onnxruntime.providers.NNAPIFlags;

I/O Contract

Inputs

Name	Type	Description
(enum constant)	NNAPIFlags	The flag to include in the configuration

Outputs

Name	Type	Description
getValue()	int	The native bitmask value for this flag

Usage Examples

import ai.onnxruntime.*;
import ai.onnxruntime.providers.NNAPIFlags;
import java.util.EnumSet;

try (OrtSession.SessionOptions opts = new OrtSession.SessionOptions()) {
    // Add NNAPI with fp16 support, disabling CPU fallback
    opts.addNnapi(EnumSet.of(NNAPIFlags.USE_FP16, NNAPIFlags.CPU_DISABLED));

    OrtEnvironment env = OrtEnvironment.getEnvironment();
    try (OrtSession session = env.createSession("/path/to/model.onnx", opts)) {
        // Model will use NNAPI with fp16 on Android
    }
}

Related Pages

• OrtSession.java - SessionOptions.addNnapi() accepts NNAPIFlags
• OrtProvider.java - NNAPI provider constant
• CoreMLFlags.java - Similar flags enum for Apple CoreML