我为我的 Activity 和 Fragment、Presenter、ViewHolder 和 ViewModel 定义了几个基类,并定义了一个接口和 Presenter,继承这些基类的所有其他活动,在我的 BaseActivity 类和 BaseFragmentClass 中,我正在创建lifecycleRegistry
对象并初始化它,但是当应用程序启动时,它会因错误而崩溃getLifecycle() returned null in ComponentActivity's constructor. Please make sure you are lazily constructing your Lifecycle in the first call to getLifecycle() rather than relying on field initialization.
文件:BaseFragment.java
package com.example.myapp.data.helper.base;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.CallSuper;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.databinding.DataBindingUtil;
import androidx.databinding.ViewDataBinding;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleRegistry;
import androidx.lifecycle.ViewModelProviders;
public abstract class BaseFragment<V extends MvpView, P extends BasePresenter<V>>
extends Fragment implements MvpView, View.OnClickListener {
private final LifecycleRegistry lifecycleRegistry = new LifecycleRegistry(this);
protected P presenter;
private int defaultValue = -1;
private ViewDataBinding viewDataBinding;
private View rootView;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
@SuppressWarnings("unchecked")
@CallSuper
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
BaseViewModel<V, P> viewModel = ViewModelProviders.of(this).get(BaseViewModel.class);
boolean isPresenterCreated = false;
if (viewModel.getPresenter() == null) {
viewModel.setPresenter(initPresenter());
isPresenterCreated = true;
}
presenter = viewModel.getPresenter();
presenter.attachLifecycle(getLifecycle());
presenter.attachView((V) this);
if (isPresenterCreated)
presenter.onPresenterCreated();
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
startUI();
}
@Override
public void onClick(View view) {
}
@NonNull
@Override
public LifecycleRegistry getLifecycle() {
return lifecycleRegistry;
}
protected abstract void startUI();
protected abstract void stopUI();
protected ViewDataBinding getViewDataBinding() {
return viewDataBinding;
}
@CallSuper
@Override
public void onDestroyView() {
super.onDestroyView();
if (presenter != null) {
presenter.detachLifecycle(getLifecycle());
presenter.detachView();
}
}
@Override
public void onDestroy() {
super.onDestroy();
if (presenter != null) {
presenter.detachLifecycle(getLifecycle());
presenter.detachView();
}
stopUI();
}
private BaseActivity<V,P> getBaseActivity() {
return ((BaseActivity<V,P>) getActivity());
}
private boolean isBaseActivityInstance() {
return getActivity() instanceof BaseActivity;
}
protected void setTitle(String title) {
if (isBaseActivityInstance()) {
getBaseActivity().setTitle(title);
}
}
protected void setClickListener(View... views) {
for (View view : views) {
view.setOnClickListener(this);
}
}
protected abstract P initPresenter();
}
文件:BaseActivity.java
package com.example.data.helper.base;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.content.ContextCompat;
import androidx.databinding.DataBindingUtil;
import androidx.databinding.ViewDataBinding;
import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.LifecycleRegistry;
import androidx.lifecycle.ViewModelProviders;
public abstract class BaseActivity<V extends MvpView, P extends BasePresenter<V>>
extends AppCompatActivity implements MvpView, View.OnClickListener, LifecycleOwner {
private final LifecycleRegistry lifecycleRegistry = new LifecycleRegistry(this) ;
protected P presenter;
private ViewDataBinding viewDataBinding;
private Menu menu;
private int defaultValue = -1;
@NonNull
@Override
public LifecycleRegistry getLifecycle() {
return lifecycleRegistry;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
super.onCreate(savedInstanceState, persistentState);
int layoutId = getLayoutId();
if (layoutId > defaultValue) {
try {
viewDataBinding = DataBindingUtil.setContentView(this, layoutId);
} catch (Exception e) {
if (viewDataBinding == null) {
setContentView(layoutId);
}
}
BaseViewModel<V,P> viewModel = ViewModelProviders.of(this).get(BaseViewModel.class);
boolean isPresenterCreated = false;
if (viewModel.getPresenter() == null) {
viewModel.setPresenter(initPresenter());
isPresenterCreated = true;
}
presenter = viewModel.getPresenter();
presenter.attachLifecycle(getLifecycle());
presenter.attachView((V) this);
if (isPresenterCreated) {
presenter.onPresenterCreated();
}
}
startUI();
}
@Override
protected void onResume() {
super.onResume();
onResumeUI();
}
protected abstract void onResumeUI();
*/
protected abstract void startUI();
protected abstract void stopUI();
protected ViewDataBinding getViewDataBinding() {
return viewDataBinding;
}
protected static void runCurrentActivity(Context context, Intent intent) {
context.startActivity(intent);
}
@Override
public void onClick(View view) {
}
@Override
protected void onDestroy() {
super.onDestroy();
this.stopUI();
presenter.detachLifecycle(getLifecycle());
presenter.detachView();
}
protected abstract P initPresenter();
protected void setTitle(String title) {
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setTitle(title);
}
}
protected void setClickListener(View... views) {
for (View view : views) {
view.setOnClickListener(this);
}
}
protected BaseFragment<?, ?> mBaseCurrentFragment;
protected void commitFragment(int parentId, BaseFragment<?, ?> baseFragment) {
getSupportFragmentManager()
.beginTransaction()
.replace(parentId, baseFragment, baseFragment.getClass().getName())
.commit();
setCurrentFragment(baseFragment);
}
protected void setCurrentFragment(BaseFragment<?, ?> baseFragment) {
this.mBaseCurrentFragment = baseFragment;
}
protected BaseFragment<?, ?> getBaseCurrentFragment() {
return mBaseCurrentFragment;
}
}
**文件:MvpView
public interface MvpView{
}
文件:BasePresenter.java
public abstract class BasePresenter<V extends MvpView> implements LifecycleObserver, Presenter<V> {
private V myMvpView;
private Bundle stateBundle;
@Override
public void attachView(V mvpView) {
myMvpView = mvpView;
}
@Override
public void detachView() {
mMvpView = null;
}
@Override
public void attachLifecycle(Lifecycle lifecycle) {
if (lifecycle != null) {
lifecycle.addObserver(this);
}
}
@Override
public void detachLifecycle(Lifecycle lifecycle) {
if (lifecycle != null) {
lifecycle.removeObserver(this);
}
}
public boolean isViewAttached() {
return myMvpView != null;
}
public V getMvpView() {
return myMvpView;
}
public Bundle getStateBundle() {
return stateBundle == null ?
stateBundle = new Bundle() : stateBundle;
}
public void checkViewAttached() {
if (!isViewAttached()) throw new MvpViewNotAttachedException();
}
public static class MvpViewNotAttachedException extends RuntimeException {
public MvpViewNotAttachedException() {
super("Please call Presenter.attachView(MvpView) before" +
" requesting data to the Presenter");
}
}
@Override
public void onPresenterDestroy() {
if (stateBundle != null && !stateBundle.isEmpty()) {
stateBundle.clear();
}
}
}
Updates:我尝试通过将 lifeCycleRegistry 设置为非 Final 来更新 BaseActivity.java 和 BaseFragment.java 的代码。并在 getLifecycle 中初始化它(如果它为 null ),但随后我只能看到一个空白屏幕,不知道为什么?
public abstract class BaseActivity<V extends MvpView, P extends BasePresenter<V>>
extends AppCompatActivity implements MvpView, View.OnClickListener {
private LifecycleRegistry = new LifeCycleRegistry(this);
@NonNull
@Override
public LifecycleRegistry getLifecycle() {
if (lifecycleRegistry==null){
lifecycleRegistry= new LifecycleRegistry(this);
}
return lifecycleRegistry;
}
}
所有其他代码都相同。