（推薦）使用ViewModelStore

代碼示例：

class MyApplication : Application(), ViewModelStoreOwner {private val mViewModelStore = ViewModelStore()override fun onCreate() {super.onCreate()}override val viewModelStore: ViewModelStoreget() = mViewModelStore/*** 手動清理 ViewModelStore*/fun clearViewModelStore() {mViewModelStore.clear()}
}

ShareViewModel:

class SharedViewModel: ViewModel() {val mShareData = MutableLiveData<String>()
}

ActivityA & ActivityB

class MainActivity : AppCompatActivity() {private val TAG = "MainActivity"private lateinit var mShareViewMode: SharedViewModeloverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)enableEdgeToEdge()setContentView(R.layout.activity_main)mShareViewMode =ViewModelProvider(application as MyApplication)[SharedViewModel::class.java]val tvTest = findViewById<TextView>(R.id.tvTest)tvTest.setOnClickListener {mShareViewMode.mShareData.value = "我是MainActivity更新的數據"startActivity(Intent(this,BActivity::class.java))}mShareViewMode.mShareData.observe(this){Log.i(TAG, "MainActivity shareData:$it")}}
}

class BActivity : AppCompatActivity() {private val TAG = "BActivity"private lateinit var mShareViewMode: SharedViewModeloverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)enableEdgeToEdge()setContentView(R.layout.activity_bactivity)// 這里傳入MyApplication的mShareViewMode =ViewModelProvider(application as MyApplication)[SharedViewModel::class.java]mShareViewMode.mShareData.observe(this) {Log.e(TAG, "BActivity onCreate shareData:$it")}}
}