这是完整的代码：
public class AddNewItem extends AppCompatActivity {
private static final int CHOOSE_IMAGE = 177;
private ImageView imageViewAdd;
private EditText titleEditText, descriptionEditText, priceEditText, cityEditText;
private String titleString, descriptionString, priceString, uploadID;
private Button buttonAdd, buttonRotateImage;
private ProgressBar progressBarImage;
private Uri uriSelectedImage;
private String downloadUriImage;
private FirebaseAuth mAuth;
private int imageRotation=0;
private AlertDialog.Builder mbuilder;
private StorageReference mStorageRef;
private DatabaseReference mDatabaseRef, mDatabaseRefUser;
private StorageTask mUploadTask;
private byte[] imageFileByte;
private Bitmap compressedImageBitmap;
int x = -10;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_new_item);
imageViewAdd = findViewById(R.id.select_image_id);
titleEditText = findViewById(R.id.title_edittext_id);
descriptionEditText = findViewById(R.id.description_edittext_id);
priceEditText = findViewById(R.id.price_edittext_id);
cityEditText = findViewById(R.id.city_textview_id);
buttonAdd = findViewById(R.id.add_item_button_id);
buttonRotateImage = findViewById(R.id.rotate_image_id);
progressBarImage = findViewById(R.id.progressbar_id);
mAuth = FirebaseAuth.getInstance();
mbuilder = new AlertDialog.Builder(this);
mStorageRef = FirebaseStorage.getInstance().getReference("uploads");
mDatabaseRef = FirebaseDatabase.getInstance().getReference("uploads");
mDatabaseRefUser = FirebaseDatabase.getInstance().getReference("Users");
}
public void selectImage(View view) {
Intent selectImageIntent = new Intent();
selectImageIntent.setType("image/*");
selectImageIntent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(selectImageIntent, "select image to show n upload"), CHOOSE_IMAGE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CHOOSE_IMAGE && resultCode == RESULT_OK && data != null && data.getData() != null) {
uriSelectedImage = data.getData();
File imageFile = new File(uriSelectedImage.getPath());
Log.e("Filepath", imageFile+"");
try {
compressedImageBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uriSelectedImage);
Log.e("Bitmap one: ", compressedImageBitmap+"");
} catch (IOException e) {
e.printStackTrace();
}
compressedImageBitmap = new Compressor(this).compressToBitmap(imageFile);
Log.e("Bitmap: ", compressedImageBitmap+"");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
compressedImageBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] imageByte = baos.toByteArray();
imageFileByte = imageByte;
Picasso.with(this).load(uriSelectedImage).into(imageViewAdd);
}
}
private String getFileExtension(Uri uri) {
ContentResolver cR = getContentResolver();
MimeTypeMap mime = MimeTypeMap.getSingleton();
return mime.getExtensionFromMimeType(cR.getType(uri));
}
//new code
public void uploadFile(View view) {
if (mUploadTask != null && mUploadTask.isInProgress()) {
Toast.makeText(this, "is in progress", Toast.LENGTH_SHORT).show();
return;
}
if (titleEditText.getText().toString().isEmpty() || titleEditText.getTextSize() < 5) {
titleEditText.setError("Title is short, minimum 5 characters");
titleEditText.requestFocus();
return;
}
if (descriptionEditText.getText().toString().isEmpty() || descriptionEditText.getTextSize() < 20) {
descriptionEditText.setError("Description is short, minimum 20 characters");
descriptionEditText.requestFocus();
return;
}
if (cityEditText.getText().toString().isEmpty() || cityEditText.length() < 3) {
cityEditText.setError("City/Location is short, minimum 3 characters");
cityEditText.requestFocus();
return;
}
if (priceEditText.getText().toString().isEmpty()) {
priceEditText.setError("Price is needed");
priceEditText.requestFocus();
return;
}
else {
if (uriSelectedImage != null) {
StorageReference fileReference = mStorageRef.child(System.currentTimeMillis() +
"." + getFileExtension(uriSelectedImage));
mUploadTask = fileReference.putBytes(imageFileByte)
.addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
//Delays the progressbar with 0.5 secs before it shows 0
//user has 0.5 secs to see the 100% bar, code is not necenssary
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
progressBarImage.setProgress(0);
}
}, 500);
Toast.makeText(AddNewItem.this, "Upload succesful", Toast.LENGTH_SHORT).show();
//Upload image is a java class.
uploadID = mDatabaseRef.push().getKey();
UploadImage uploadImage = new UploadImage(titleEditText.getText().toString(),
taskSnapshot.getDownloadUrl().toString(), descriptionEditText.getText().toString(),
cityEditText.getText().toString(), priceEditText.getText().toString(),
imageRotation, lanButton.getText().toString(), mAuth.getCurrentUser().getUid(),
uploadID, mAuth.getCurrentUser().getEmail());
mDatabaseRef.child(uploadID).setValue(uploadImage);
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(AddNewItem.this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
})
.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
@Override
public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
progressBarImage.setProgress((int) progress);
}
});
} else {
Toast.makeText(this, "no file selected", Toast.LENGTH_SHORT).show();
}
}
}
public void rotateImage(View view) {
imageViewAdd.setRotation(imageViewAdd.getRotation() + 90);
imageRotation = (int) imageViewAdd.getRotation();
}
@Override
protected void onStart() {
super.onStart();
if(mAuth.getCurrentUser() == null){
Intent mainActivityIntent = new Intent(this, MainActivity.class);
startActivity(mainActivityIntent);
finish();
}
else {
mDatabaseRefUser.child(mAuth.getCurrentUser().getUid()).child("Online").setValue(true);
}
}
}
这是我得到的错误原因：java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
我在compressedImageBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);行的onActivityResult中得到它
我不知道问题是什么，为什么我会得到Nullpointerexception。无论如何，我能解决这个问题吗？我正在尝试从图库中选择一个图像，然后对其进行压缩。之后，我想将其上传到Firebase存储。我已经寻找了好几个小时的解决方案，但似乎没有任何效果。
如何解决此问题？我如何将compressedImageBitmap设置为某种值，使其不显示null并可以进行压缩。因为目前我是从图库中选取图片，但仍然显示为Null。我确实拥有<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
在Logcat中，它还会显示E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /document/image:1204 (No such file or directory) when I chose an image from gallery.
这是来自Logcat的
E/Filepath: /document/image:1204
E/Bitmap one:: android.graphics.Bitmap@8d6ccc1
E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /document/image:1204 (No such file or directory)
E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /document/image:1204 (No such file or directory)
E/Bitmap: null