尝试设置Image时，Android ImageView空对象

如何解决尝试设置Image时，Android ImageView空对象

我很难用来自Firebase存储数据库的用户对象中的字符串下载URL设置ImageView。 setimage（）方法说Imageview是一个空对象，当我尝试调试它时，它是正确的，它显示为空。我该如何解决。我认为这与匿名内部类有关。

public class DashBoard extends AppCompatActivity {
    private FirebaseAuth mAuth;
    private ArrayList<String> motivatingMessages;
    private Button gymLocations,profile,health;
    public ImageView profileImageView;
    private TextView welcome;

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        showProfilePicture();
        profileImageView = findViewById(R.id.personalProfile);
        mAuth = FirebaseAuth.getInstance();
        FirebaseUser user = mAuth.getCurrentUser();
        setContentView(R.layout.activity_dash_board);
        //getSupportActionBar().setTitle("Welcome To Bodify");
        profile = findViewById(R.id.buttonProfile);
        gymLocations = findViewById(R.id.gymFinderButton);
        health = findViewById(R.id.healthButton);
        welcome = findViewById(R.id.welcomeUser);

        final String userID = mAuth.getUid();
        DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("User").child(userID);
        databaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                User user = snapshot.getValue(User.class);
                if (user != null) {
                    welcome.setText("User Logged in: ");
                    welcome.append(user.getUserName());
                }
            }
            @Override
            public void onCancelled(@NonNull DatabaseError error) {
                Toast.makeText(DashBoard.this,"Error Occurred: " + error.getMessage(),Toast.LENGTH_SHORT).show();
            }
        });


        gymLocations.setonClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(getApplicationContext(),GymsNearMe.class));
            }
        });
        profile.setonClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(getApplicationContext(),PersonalProfile.class));
            }
        });
        health.setonClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(DashBoard.this,Health.class));
            }
        });

    }


    public void showProfilePicture() {

        mAuth = FirebaseAuth.getInstance();
        final String userID = mAuth.getUid();
        DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("User").child(userID);
        databaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                User user = snapshot.getValue(User.class);
                String image = user.getmImageUrl();
                setimage(image);
            }
            @Override
            public void onCancelled(@NonNull DatabaseError error) {
                Toast.makeText(DashBoard.this,Toast.LENGTH_SHORT).show();
            }
        });
    }

    public void setimage(String image) {
        Picasso.get().load(image).into(profileImageView);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu,menu);
        return true;
    }

    @Override
    public boolean onoptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.logout) {
            mAuth.signOut();
            startActivity(new Intent(getApplicationContext(),LogIn.class));
        }
        return true;
    }
}

enter code here

解决方法

您似乎在扩大版面之前试图找到视图：

profileImageView = findViewById(R.id.personalProfile);

在通货膨胀之后移动那条线，所以在那条线之后：

setContentView(R.layout.activity_dash_board);

换句话说，行的顺序应为：

setContentView(R.layout.activity_dash_board);

mAuth = FirebaseAuth.getInstance();
FirebaseUser user = mAuth.getCurrentUser();

profileImageView = findViewById(R.id.personalProfile);
showProfilePicture();

，您无需在mAuth

中再次设置showProfilePicture ,

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dash_board);
profileImageView = findViewById(R.id.personalProfile);
profile = findViewById(R.id.buttonProfile);
gymLocations = findViewById(R.id.gymFinderButton);
health = findViewById(R.id.healthButton);
welcome = findViewById(R.id.welcomeUser);
showProfilePicture();
mAuth = FirebaseAuth.getInstance();
FirebaseUser user = mAuth.getCurrentUser();

尝试此顺序