错误：尝试在空对象引用上调用虚拟方法'android.content.Context.getResources()'

Question

大家好，谢谢你阅读这篇文章。我有一个问题，那就是当我看到一般的logcat时，logcat会在类活动/片段/或我创建类的任何内容中给出信息错误行。 但是我在logcat中感到奇怪，它没有显示行错误代码。

我的日志猫

06-19 22:50:31.441 3980-3980/com.tenagakerja.tenagakerja E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.tenagakerja.tenagakerja, PID: 3980
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tenagakerja.tenagakerja/com.tenagakerja.tenagakerja.ui.login.LoginActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.content.ContextWrapper.getResources(ContextWrapper.java:86)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:74)
at android.support.v7.app.AppCompatActivity.getResources(AppCompatActivity.java:542)
at android.view.Window.getDefaultFeatures(Window.java:1306)
at android.view.Window.<init>(Window.java:453)
at com.android.internal.policy.impl.PhoneWindow.<init>(PhoneWindow.java:290)
at com.android.internal.policy.impl.Policy.makeNewWindow(Policy.java:60)
at com.android.internal.policy.PolicyManager.makeNewWindow(PolicyManager.java:57)
at android.app.Activity.attach(Activity.java:5932)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2259)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

这是我的活动代码：

public class LoginActivity extends BaseActivity<ActivityLoginBinding, LoginViewModel> implements LoginNavigator {
@Inject
public LoginViewModel loginViewModel;
private ActivityLoginBinding activityLoginBinding;
@Override
public int getBindingVariable() {
return BR.loginViewModel;
}
@Override
public int getLayoutId() {
return R.layout.activity_login;
}
@Override
public LoginViewModel getViewModel() {
return loginViewModel;
}
@Override
public void handleError(Throwable throwable) {
Timber.d(throwable);
}
@Override
public void login() {
String email = activityLoginBinding.loginEditEmail.getText().toString();
String password = activityLoginBinding.loginEditPassword.getText().toString();
loginViewModel.login(email, password);
}
@Override
public void openMainActivity() {
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityLoginBinding = getViewDataBinding();
loginViewModel.setNavigator(this);
//        Toolbar toolbar = findViewById(R.id.toolbar);
//        setSupportActionBar(toolbar);
}
}

基本活动

public abstract class BaseActivity<T extends ViewDataBinding, V extends BaseViewModel> extends AppCompatActivity implements BaseFragment.Callback{
private ProgressDialog progressDialog;
private T viewDataBinding;
private V viewModel;
public abstract int getBindingVariable();
public abstract @LayoutRes int getLayoutId();
public abstract V getViewModel();
@Override
public void onFragmentAttached() {
}
@Override
public void onFragmentDetached(String tag) {
}
@Override
protected void attachBaseContext(Context newBase) {
}
@Override
protected void onCreate(@Nullable Bundle saveInstanceState) {
super.onCreate(saveInstanceState);
performDependencyInjection();
performDataBinding();
}
public T getViewDataBinding() {
return viewDataBinding;
}
@TargetApi(Build.VERSION_CODES.M)
public boolean hasPermission(String permission) {
return Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||checkSelfPermission(permission)
== PackageManager.PERMISSION_GRANTED;
}
public void hideKeyboard() {
View view = this.getCurrentFocus();
if (view != null) {
InputMethodManager imm = (InputMethodManager) this.getSystemService(Context.INPUT_METHOD_SERVICE);
if (imm != null) {
imm.hideSoftInputFromInputMethod(view.getWindowToken(), 0);
}
}
}
public void hideLoading() {
if (progressDialog != null && progressDialog.isShowing()) {
progressDialog.cancel();
}
}
public boolean isNetworkConnected() {
return NetworkUtils.isNetworkConnected(getApplicationContext());
}
public void performDependencyInjection() {
AndroidInjection.inject(this);
}
@TargetApi(Build.VERSION_CODES.M)
public void requestPermissionSafely(String[] permission, int requestCode) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(permission, requestCode);
}
}
public void showLoading() {
hideLoading();
progressDialog = CommonUtils.showLoadingDialog(getApplicationContext());
}
private void performDataBinding() {
viewDataBinding = DataBindingUtil.setContentView(this, getLayoutId());
this.viewModel = viewModel == null ? getViewModel() : viewModel;
viewDataBinding.setVariable(getBindingVariable(), viewModel);
viewDataBinding.executePendingBindings();
}
}

Answer 1

已解决

我取消注释附加基本上下文，是的，错误消失了:D