无效的参数类型。必须是LifecycleOwner的一个实例

Question

我正在尝试使用lifeCycleOwner和lifecycleObserve。当我调用 lifecycleOwner.getLifecycle（）。addObserver（this）;

时，出现以下异常

invalid parameter type. Must be one and instanceof LifecycleOwner

如下所示的代码

public class TestActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test_activity);

        new  TestObserver(this,this);
    }   
    }

public class TestObserver implements LifecycleObserver{

  public TestObserver(LifecycleOwner lifecycleOwner, Context context){
        lifecycleOwner.getLifecycle().addObserver(this);
    }
}

已编辑： 根据要求Build.gradle文件

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.example.test"
        minSdkVersion 14
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        multiDexEnabled true
    }


    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:design:27.1.1'
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support:cardview-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.2'

    // ViewModel and LiveData ,lifecycleObserver
    implementation 'android.arch.lifecycle:extensions:1.1.1'
    implementation "android.arch.lifecycle:runtime:1.1.1"

}

apply plugin: 'com.google.gms.google-services'
apply plugin: 'io.fabric'

Answer 1

在LifecycleObserver中重写onCreate或其他事件时，请勿将任何参数传递给该方法。

这会导致您的错误：

let errors = {
  location: {
    coordinates: []
  }
}

这是正确的声明：

@OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
protected void onCreate(Bundle savedInstanceState)

Answer 2

这是您的观察员类别：

public class TestObserver implements LifecycleObserver {

private Activity activity;


public void ActivityRecognitionHelper(LifecycleOwner lifecycleOwner, Activity activity){
    this.activity = activity;
    lifecycleOwner.getLifecycle().addObserver(this);
}

}

您可以通过以下方式从任何活动中调用上述“观察者类”：

new TestObserver().ActivityRecognitionHelper(this, this);

Answer 3

标记的答案不正确。

允许将类型为LifecycleOwner的参数作为第一个参数。可选，可以添加Lifecycle.Event作为第二自变量。在第二种情况下，注释必须为Lifecycle.Event.ON_ANY。这两个有效选项：

@OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
private fun onCreate(owner: LifecycleOwner) {}

@OnLifecycleEvent(Lifecycle.Event.ON_ANY) // << Must be ON_ANY
private fun onAnyEvent(owner: LifecycleOwner, event: Lifecycle.Event) {}

---

说明，请参见androidx.lifecycle.ClassesInfoCache的源代码：