这是在我通过设置活动从Firebase调用用户个人资料图像时发生的。
public class MainActivity extends AppCompatActivity {
private NavigationView navigationView;
private DrawerLayout drawerLayout;
private ActionBarDrawerToggle actionBarDrawerToggle;
private RecyclerView postList;
private Toolbar mToolbar;
private FirebaseAuth mAuth;
private CircleImageView NavProfileImage;
private TextView NavProfileUserName;
private DatabaseReference UsersRef;
String currentUsersID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
currentUsersID = mAuth.getCurrentUser().getUid();
UsersRef = FirebaseDatabase.getInstance().getReference().child("Users");
mToolbar = (Toolbar) findViewById(R.id.main_page_toolbar);
setSupportActionBar(mToolbar);
getSupportActionBar().setTitle("Home");
drawerLayout = (DrawerLayout) findViewById(R.id.drawable_layout);
actionBarDrawerToggle = new ActionBarDrawerToggle(MainActivity.this, drawerLayout, R.string.drawer_open, R.string.drawer_close);
drawerLayout.addDrawerListener(actionBarDrawerToggle);
actionBarDrawerToggle.syncState();
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
navigationView = (NavigationView) findViewById(R.id.navigation_view);
View navView = navigationView.inflateHeaderView(R.layout.navigation_header);
NavProfileImage = (CircleImageView) navView.findViewById(R.id.nav_profile_image);
NavProfileUserName = (TextView) navView.findViewById(R.id.nav_user_full_name);
UsersRef.child(currentUsersID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
if (dataSnapshot.hasChild("fullname")) {
String fullname = dataSnapshot.child("fullname").getValue().toString();
NavProfileUserName.setText(fullname);
}
if (dataSnapshot.hasChild("profileimage")) {
String image = dataSnapshot.child("profileimage").getValue().toString();
Picasso.get().load(image).placeholder(R.drawable.profile).into(NavProfileImage);
} else {
Toast.makeText(MainActivity.this, "Profile name do not exists...", Toast.LENGTH_SHORT).show();
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
UserMenuSelector(menuItem);
return false;
}
});
}
这是我的设置活动，用户在其中输入数据。效果很好，但是当我尝试在主要活动中将此数据加载到导航抽屉中时，该应用程序在安装后将无法启动。
private EditText UserName, FullName, CountryName;
private Button SaveInformationButton;
private CircleImageView ProfileImage;
private ProgressDialog loadingBar;
private FirebaseAuth mAuth;
private DatabaseReference UsersRef;
private StorageReference UserProfileImageRef;
String currentUserID;
final static int Gallery_Pick = 1;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_setu);
mAuth = FirebaseAuth.getInstance();
currentUserID = mAuth.getCurrentUser().getUid();
UsersRef = FirebaseDatabase.getInstance().getReference().child(currentUserID);
UserProfileImageRef = FirebaseStorage.getInstance().getReference().child("Profile Images");
UserName = (EditText) findViewById(R.id.setup_username);
FullName = (EditText) findViewById(R.id.setup_full_name);
CountryName = (EditText) findViewById(R.id.setup_country_name);
SaveInformationButton = (Button) findViewById(R.id.setup_information_button);
ProfileImage = (CircleImageView) findViewById(R.id.setup_profile_image);
loadingBar = new ProgressDialog(this);
SaveInformationButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
SaveAccountSetupInformation();
}
});
ProfileImage.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Intent galleryIntent = new Intent();
galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
galleryIntent.setType("image/*");
startActivityForResult(galleryIntent, Gallery_Pick);
}
});
UsersRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot)
{
if (dataSnapshot.exists())
{
String image = dataSnapshot.child("profileimage").getValue().toString();
Picasso.get().load(image).placeholder(R.drawable.profile).into(ProfileImage);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == Gallery_Pick && resultCode==RESULT_OK && data != null)
{
Uri ImageUri = data.getData();
CropImage.activity()
.setGuidelines(CropImageView.Guidelines.ON)
.setAspectRatio(1, 1)
.start(this);
}
if (requestCode==CropImage.CROP_IMAGE_ACTIVITY_REQUEST_CODE)
{
CropImage.ActivityResult result = CropImage.getActivityResult(data);
if (resultCode == RESULT_OK)
{
loadingBar.setTitle("Profile Image");
loadingBar.setMessage("Please Wait While We Are Updating Your Profile Image");
loadingBar.show();
loadingBar.setCanceledOnTouchOutside(true);
Uri resultUri = result.getUri();
StorageReference filePath = UserProfileImageRef.child(currentUserID + ".jpg");
filePath.putFile(resultUri).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>()
{
@Override
public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task)
{
if (task.isSuccessful())
{
Toast.makeText(SetuActivity.this, "Profile Image Is Added Successfully", Toast.LENGTH_SHORT).show();
final String downloadUrl = task.getResult().getDownloadUrl().toString();
UsersRef.child("profileimage").setValue(downloadUrl)
.addOnCompleteListener(new OnCompleteListener<Void>()
{
@Override
public void onComplete(@NonNull Task<Void> task)
{
if (task.isSuccessful())
{
Intent selfIntent = new Intent(SetuActivity.this, SetuActivity.class);
startActivity(selfIntent);
Toast.makeText(SetuActivity.this, "Profile Image Stored To Firebase Database Successfully", Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
}
else
{
String message = task.getException().getMessage();
Toast.makeText(SetuActivity.this, "Error Occured: " + message, Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
}
}
});
}
}
});
}
else
{
Toast.makeText(this, "Error Occured: Image can't be cropped, Try Again.", Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
}
}
}
这是我每次运行程序时收到的错误消息。
W/dalvikvm: threadid=1: calling UncaughtExceptionHandler
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sample, PID: 27888
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sample/com.sample.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2441)
at android.app.ActivityThread.access$900(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5345)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.sample..MainActivity.onCreate(MainActivity.java:55)
at android.app.Activity.performCreate(Activity.java:5343)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2441)
at android.app.ActivityThread.access$900(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5345)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
at dalvik.system.NativeStart.main(Native Method)
Application terminated.
字符串函数是问题所在。因为每当我从代码中删除它时，该应用程序都能完美运行而不会崩溃。我不知道如何在这里问问题，所以请原谅我的错误，对于造成的延迟，我们深表歉意。