Android 不保存 TextInputEditText 的狀態

Question

所以我之前問了一個題為“ 使用導航抽屜從片段 A 切換到片段 B，使片段 A 停止工作”的問題，經過大量研究后，我意識到我什至沒有嘗試保存片段的狀態。 經過一整天的故障排除后，我仍然沒有它，所以回來尋求如何解決這個問題的智慧。 就像我在上一個問題中所說的那樣，我是新手，所以不太了解這一切，所以希望不要讓自己太尷尬。

對於上下文，該應用程序是一個語言翻譯應用程序，您輸入文本，點擊按鈕translate ，然后閱讀結果。 當切換片段時，即Home到Gallery然后回到Home ，翻譯和文本輸入消失了。

簡單地說，為什么我的文本在切換時沒有被保存？

我擁有的 onCreate 代碼是：

  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if(savedInstanceState != null)
        {
            sourceEdit.setText(savedInstanceState.getString("textKey"));

        }

onSaveInstanceState：

 @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putString("textKey", sourceEdit.getText().toString());
    }

完整的代碼只是為了：

public class MainDrawerActivity extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;
    private ActivityMainDrawerBinding binding;
    private Spinner fromSpinner, toSpinner;
    private TextInputEditText sourceEdit;
    private ImageView micIV;
    private MaterialButton translateBtn;
    private TextView translatedTV;
    String[] fromLanguages = {"From","English","Korean"};
    String[] toLanguages = {"From","English","Korean"};


    private static final int REQUEST_PERMISSION_CODE = 1;
    int languageCode, fromLanguageCode, toLanguageCode = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if(savedInstanceState != null)
        {
            sourceEdit.setText(savedInstanceState.getString("textKey"));

        }

        binding = ActivityMainDrawerBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        setSupportActionBar(binding.appBarMainDrawer.toolbar);

        DrawerLayout drawer = binding.drawerLayout;
        NavigationView navigationView = binding.navView;
        // Passing each menu ID as a set of Ids because each
        // menu should be considered as top level destinations.
        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
                .setOpenableLayout(drawer)
                .build();
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main_drawer);
        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);

        //start of language code

        fromSpinner = findViewById(R.id.idFromSpinner);
        toSpinner = findViewById(R.id.idToSpinner);
        sourceEdit = findViewById(R.id.idEditSource);
        micIV = findViewById(R.id.idIVMic);
        translateBtn = findViewById(R.id.idButtonTranslate);
        translatedTV = findViewById(R.id.idTVTranslatedTV);

        fromSpinner.setOnItemSelectedListener(new OnItemSelectedListener(){
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                fromLanguageCode = getLanguageCode(fromLanguages[position]);
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

        ArrayAdapter fromAdapter = new ArrayAdapter(this, R.layout.spinner_item, fromLanguages);
        fromAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        fromSpinner.setAdapter(fromAdapter);

        toSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                toLanguageCode = getLanguageCode(toLanguages[position]);
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

        ArrayAdapter toAdapter = new ArrayAdapter(this,R.layout.spinner_item, toLanguages);
        toAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        toSpinner.setAdapter(toAdapter);

        translateBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                translatedTV.setText("");
                if(sourceEdit.getText().toString().isEmpty()){
                    makeText(MainDrawerActivity.this, "Please enter text", Toast.LENGTH_SHORT).show();
                }
                else if(fromLanguageCode==0){
                    makeText(MainDrawerActivity.this, "Please select source language", Toast.LENGTH_SHORT).show();
                }
                else if(toLanguageCode==0){
                    makeText(MainDrawerActivity.this, "Please select language to translate too", Toast.LENGTH_SHORT).show();
                } else {
                    translateText(fromLanguageCode, toLanguageCode, sourceEdit.getText().toString());

                }
                InputMethodManager inputManager = (InputMethodManager)
                        getSystemService(Context.INPUT_METHOD_SERVICE);

                inputManager.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(),
                        InputMethodManager.HIDE_NOT_ALWAYS);
            }
        });

        micIV.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
                i.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
                i.putExtra(RecognizerIntent.EXTRA_LANGUAGE, Locale.getDefault());
                i.putExtra(RecognizerIntent.EXTRA_PROMPT,"Speak to translate text");
                try {
                    startActivityForResult(i, REQUEST_PERMISSION_CODE);
                } catch (Exception e){
                    e.printStackTrace();
                    Toast.makeText(MainDrawerActivity.this, " "+e.getMessage(), Toast.LENGTH_SHORT).show();
                }

            }
        });
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putString("textKey", sourceEdit.getText().toString());
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode==REQUEST_PERMISSION_CODE){
            if(resultCode==RESULT_OK && data!=null){
                ArrayList<String> result = data.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
                sourceEdit.setText(result.get(0));
            }
        }
    }
    private void translateText(int fromLanguageCode, int toLanguageCode, String source) {
        translatedTV.setText("Downloading Model...");
        FirebaseTranslatorOptions options = new FirebaseTranslatorOptions.Builder()
                .setSourceLanguage(fromLanguageCode)
                .setTargetLanguage(toLanguageCode)
                .build();
        FirebaseTranslator translator = FirebaseNaturalLanguage.getInstance().getTranslator(options);

        FirebaseModelDownloadConditions conditions = new FirebaseModelDownloadConditions.Builder().build();

        translator.downloadModelIfNeeded(conditions).addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void unused) {
                translatedTV.setText("Translating...");
                translator.translate(source).addOnSuccessListener(new OnSuccessListener<String>() {
                    @Override
                    public void onSuccess(String s) {
                        translatedTV.setText(s);
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(MainDrawerActivity.this, "Failed to translate: " + e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                });
            }
        }).addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Toast.makeText(MainDrawerActivity.this, "Failed to download model... " + e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    //Method that gets the languages from Firebase
    public int getLanguageCode(String language) {
        int languageCode = 0;
        switch (language) {
            case "English":
                languageCode = FirebaseTranslateLanguage.EN;
                break;
            case "Korean":
                languageCode = FirebaseTranslateLanguage.KO;
                break;
            default:
                languageCode = 0;
        }
        return languageCode;
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main_drawer, menu);
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main_drawer);
        return NavigationUI.navigateUp(navController, mAppBarConfiguration)
                || super.onSupportNavigateUp();
    }
}

Answer 1

  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if(savedInstanceState != null)
        {
            sourceEdit.setText(savedInstanceState.getString("textKey"));

        }

如果這發生在片段中。 尚未創建 UI。 所以你必須保存在一些變量中。

String myEditString;
  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if(savedInstanceState != null)
        {
            myEditString = savedInstanceState.getString("textKey");

        }

而不是在onViewCrated()進行插入，並且必須在片段中進行插入。 或者只使用 jetpack 中的 ViewModel 類
好的，我看到你從活動中編碼。 嘗試訪問它時，您沒有初始化您的 sourceEdit。 如果您使用綁定，則不必將所有 UI 保存在變量中。 它會將它們全部保留，只需使用binding.yourIdInXml