我正在尝试使用 getApplicationContext() 将用户从一个 java 类传递到另一个类。不幸的是它不起作用并且返回 null。我希望将用户信息从 LoginActivity 传递到 CustomMapActivity。用户信息存储在 firebase 中,这可能是一个问题吗?
我相信 list 是正确的。请参阅下文。
<activity android:name=".ui.MapCustomActivity"></activity>
<activity android:name=".ui.LoginActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".ui.RegisterActivity" />
<activity android:name=".ui.ProfileActivity" />
<activity android:name=".ui.MapCustomActivity"></activity>
下面是登录 Activity ,
public class LoginActivity extends AppCompatActivity implements
View.OnClickListener
{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mEmail = findViewById(R.id.email);
mPassword = findViewById(R.id.password);
mProgressBar = findViewById(R.id.progressBar);
setupFirebaseAuth();
findViewById(R.id.email_sign_in_button).setOnClickListener(this);
findViewById(R.id.link_register).setOnClickListener(this);
hideSoftKeyboard();
}
private void showDialog(){
mProgressBar.setVisibility(View.VISIBLE);
}
private void hideDialog(){
if(mProgressBar.getVisibility() == View.VISIBLE){
mProgressBar.setVisibility(View.INVISIBLE);
}
}
private void setupFirebaseAuth(){
Log.d(TAG, "setupFirebaseAuth: started.");
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
//user = null;
if (user != null) {
Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getEmail());
Toast.makeText(LoginActivity.this, "Authenticated with: " + user.getEmail(), Toast.LENGTH_SHORT).show();
FirebaseFirestore db = FirebaseFirestore.getInstance();
FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder()
.setTimestampsInSnapshotsEnabled(true)
.build();
db.setFirestoreSettings(settings);
DocumentReference userRef = db.collection(getString(R.string.collection_users))
.document(user.getUid());
userRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
@Override
public void onComplete(@NonNull Task<DocumentSnapshot> task) {
if(task.isSuccessful()){
Log.d(TAG, "onComplete: successfully set the user client." + task.getResult());
User user = task.getResult().toObject(User.class);
((UserClient)(getApplicationContext())).setUser(user);
}
}
});
Intent intent = new Intent(LoginActivity.this, MapCustomActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
finish();
} else {
// User is signed out
Log.d(TAG, "onAuthStateChanged:signed_out");
}
// ...
}
};
}
下面是 MapCustomActivity:
public class MapCustomActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_map_custom);
photoview2 = (ImageView) findViewById(R.id.limerickMapImageView);
mAvatarImage = (ImageView) findViewById(R.id.imageChooseAvatar);
photoview2.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
view.bringToFront();
viewTransformation(view, event);
return true;
}
});
retrieveProfileImage();
}
private void retrieveProfileImage(){
RequestOptions requestOptions = new RequestOptions()
.error(R.drawable.cwm_logo)
.placeholder(R.drawable.cwm_logo);
int avatar = 0;
try{
avatar = Integer.parseInt(((UserClient)getApplicationContext()).getUser().getAvatar());
}catch (NumberFormatException e){
Log.e(TAG, "retrieveProfileImage: no avatar image. Setting default. " + e.getMessage() );
}
Glide.with(MapCustomActivity.this)
.setDefaultRequestOptions(requestOptions)
.load(avatar)
.into(mAvatarImage);
}
下面是 UserClient 类
public class UserClient extends Application {
private User user = null;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
最佳答案
要使用 Intent 将数据从一个 Activity 传递到其他 Activity ,请确保您执行了以下步骤。
- 第 1 步在源中创建新的显式或隐式 Intent 对象 Activity 。
- 第2步调用intent.putExtra(String key, Object data)方法将数据保存到其中。
- 第 3 步在源 Activity 中调用 startActivity(intent) 方法,将 Intent 传递给 Android 操作系统。
- 步骤 4 在目标 Activity 中调用 getIntent() 方法。
在你的情况下,我认为你错过了第2步
关于Java Android getApplicationContext() 从上一个类返回一个 null 对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54818075/