Integrate C++ Code In Your Existing Camera Application

In today's video, we'll walk through integrating a C++ file into an existing Android project and displaying its content in the activity.

Watch the Video Tutorial

If you prefer a step-by-step walkthrough, watch the video tutorial below:

Step-by-Step Integration

1. Set Up Your Project

Start by opening your project hierarchy. Click on Android, then Project. Right-click on app and create a new directory named CPP. Inside this directory, create a new file named CMakeLists.txt. Make sure the name is exact to avoid errors later.

2. Configure CMakeLists.txt

Add the following CMake version and configuration to the CMakeLists.txt file:

         cmake_minimum_required(VERSION 3.10.2)
        project(ChannelDetails)

        add_library(channel_details SHARED channel_details.cpp)
        find_library(log-lib log)
        target_link_libraries(channel_details ${log-lib})
    

3. Update build.gradle

In your build.gradle file, add a new block for externalNativeBuild:

 android {
            ...
            externalNativeBuild {
                cmake {
                    path "src/main/cpp/CMakeLists.txt"
                }
            }
        }
        
    

Sync your project after making these changes.

4. Move and Update the C++ File

Move the channel_details.cpp file into the cpp directory. Update this file to be compatible with JNI. Replace iostream with jni.h, and modify the method to use JNI conventions:

         extern "C" JNIEXPORT jstring JNICALL
        Java_com_example_myapp_MainActivity_getChannelDetails(JNIEnv *env, jobject obj) {
            std::string channelName = "Example Channel";
            return env->NewStringUTF(channelName.c_str());
        }
    

5. Update MainActivity

In your MainActivity class, load the native library and declare the native method:

         static {
            System.loadLibrary("channel_details");
        }

        public native String getChannelDetails();
    

Call this method to retrieve and display the channel name:

         TextView channelNameTextView = findViewById(R.id.channel_name);
        channelNameTextView.setText(getChannelDetails());
    

6. Run Your Application

Run your application to see the returned string from the C++ code displayed in your activity.