我的应用程序第一次运行，然后一直崩溃

Question

我启动了我的应用程序，在newJoke textview中撰写了一篇文章，在newMeme imageview中添加了图片，然后单击了newJokeButton按钮。将该帖子添加到firebase实时数据库中，并将图像存储在firebase存储器中的次数与我单击按钮的次数相同。但是，然后，我在模拟器上按了返回键，然后再次进入发布页面，但是随后在单击发布按钮之后，应用程序继续停止。请帮助

我面临的第二个问题是，如果newJoke为空，我不希望将图像添加到存储中。我该如何实现？

我尝试卸载并重新启动应用程序。我在logcat中搜索错误，但没有找到解决方法。

PostActivity.java

public class PostActivity extends AppCompatActivity {

    public static int RESULT_LOAD_IMAGE = 1;
    private EditText newJoke;
    private Button newJokeBtn;
    private ImageButton newMemeBtn;
    private Uri uri = null;
    private ImageView newMeme;
    private static final String TAG = "PostActivity";

    DatabaseReference databasePosts;
    private StorageReference storage;
    private FirebaseUser user;
    private StorageReference memesRef;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        setTheme(R.style.HomeTheme);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_post);

        databasePosts = FirebaseDatabase.getInstance().getReference("posts");

        storage = FirebaseStorage.getInstance().getReference("memes");

        memesRef = FirebaseStorage.getInstance().getReference();

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

        newJoke = findViewById(R.id.editjoke);
        newJokeBtn = findViewById(R.id.postBtn);
        newMeme = findViewById(R.id.imagememe);
        newMemeBtn = findViewById(R.id.memebutton);

        newMemeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getImageFromAlbum();

            }
        });


        newJokeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                addPost();
                final Animation myAnim = AnimationUtils.loadAnimation(PostActivity.this, R.anim.milkshake);
                newJokeBtn.setAnimation(myAnim);
                view.startAnimation(myAnim);
                newJoke.setText("");
                newMeme.setImageDrawable(null);
            }
        });
    }

    private void getImageFromAlbum() {




        try {
            Intent i = new Intent(Intent.ACTION_PICK,
                    android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            startActivityForResult(i, RESULT_LOAD_IMAGE);
        } catch (Exception exp) {
            Log.i("Error", exp.toString());
        }


    }


    public void addPost() {

        String joke = newJoke.getText().toString().trim();
        String memeuri = uri.toString();


        if (!TextUtils.isEmpty(joke)) {


            String id = databasePosts.push().getKey();
            Post post = new Post(id, joke, memeuri);
            databasePosts.child(id).setValue(post);
            Toast.makeText(getApplicationContext(), "Haha", Toast.LENGTH_LONG).show();
        }
    }


        @Override
        protected void onActivityResult ( int requestCode, int resultCode, @Nullable final Intent data){
            super.onActivityResult(requestCode, resultCode, data);
            if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK) {
                try {

                    Uri selectedImageUri = data.getData();
                    InputStream imageStream = getContentResolver().openInputStream(selectedImageUri);
                    Bitmap selectedImage = BitmapFactory.decodeStream(imageStream);
                    newMeme.setImageBitmap(selectedImage);

                    // Get a reference to store file at chat_photos/<FILENAME>
                    final StorageReference photoRef = storage.child("memes").child(selectedImageUri
                            .getLastPathSegment());

                    // Upload file to Firebase Storage
                    photoRef.putFile(selectedImageUri)
                            .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                                @Override
                                public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                                    // Download file From Firebase Storage
                                    photoRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                                        @Override
                                        public void onSuccess(Uri downloadPhotoUrl) {

                                            uri = downloadPhotoUrl;


                                        }
                                    });
                                }
                            });
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                    Toast.makeText(PostActivity.this, "Something went wrong", Toast.LENGTH_LONG).show();
                }
            }
        }



}

AndroidManifest.xml

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme.Launcher">
        <activity android:name=".PostActivity"></activity>
        <activity android:name=".FeedActivity">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
            </intent-filter>
        </activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

Post.java（Java模型类）

public class Post {
    String postId;

    String postJoke;

    String postMeme;

    public Post(){}

    public Post(String postId, String postJoke, String postMeme) {
        this.postId = postId;

        this.postJoke = postJoke;

        this.postMeme = postMeme;
    }

    public String getPostId() {
        return postId;


    }



    public String getPostJoke() {
        return postJoke;
    }

    public String getPostMeme() {
        return postMeme;
    }


}

请帮助我。