Android Roomを使用して家計簿アプリを作成しています。
今、取り組んでいる仕様は、
ShopFragment画面の検索ボタンでListViewに表示されるアイテムをタップしたら、
そのアイテムのidをIntentで別画面(NewBudgetTracker)に渡し、
NewBudgetTrackerに渡されたidを元にAndroid Room DBからselect文を発行し、
当該selectの結果を入力画面に表示し、最終的にはそこにEditボタンを追加し、
update文で編集する機能を付けたいと思っています。
現在、出ているエラーは、下記となります。
エラー内容を見ると、NewBudgetTrackerの58行目のshopFragmentIntentIdがNullPointerになっていると読み取れる為、
57行目にLog.dを配置し、確認した所、タップされたアイテムの番号がコンソール上に表示されていました。
また、デバッグモードで、58行目にブレークポイントを貼った際も、shopFragmentIntentIdにはタップされたアイテムの番号が入っていたため、
何故、NullPointerになっているのか原因が掴めておりません。
解決の為、ヒントを頂ける方がおられましたら、ご助力の程よろしくお願いいたします。
エラー文
2022-04-20 20:15:14.354 10732-10732/com.myproject.offlinebudgettrackerappproject E/AndroidRuntime: FATAL EXCEPTION: main Process: com.myproject.offlinebudgettrackerappproject, PID: 10732 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myproject.offlinebudgettrackerappproject/com.myproject.offlinebudgettrackerappproject.NewBudgetTracker}: java.lang.NullPointerException: Attempt to invoke virtual method 'androidx.lifecycle.LiveData com.myproject.offlinebudgettrackerappproject.model.BudgetTrackerViewModel.getBudgetTrackerId(int)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'androidx.lifecycle.LiveData com.myproject.offlinebudgettrackerappproject.model.BudgetTrackerViewModel.getBudgetTrackerId(int)' on a null object reference at com.myproject.offlinebudgettrackerappproject.NewBudgetTracker.onCreate(NewBudgetTracker.java:58) at android.app.Activity.performCreate(Activity.java:7825) at android.app.Activity.performCreate(Activity.java:7814) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1306) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
下記はアイテムを表示する画面のコードです。
ShopFragment.java (コードが長い為、一部のみ掲載)
// Todo 2022/04/10 Tapped modified storeListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { String date = adapterView.getItemAtPosition(position).toString(); List<BudgetTracker> budgetListItems = viewModelStoreNameLists; int intId = (int) id; BudgetTracker storeItemId = budgetListItems.get(intId); Toast.makeText(getActivity(), Long.toString(storeItemId.getId()), Toast.LENGTH_SHORT).show(); Toast.makeText(getActivity(), storeItemId.getStoreName(), Toast.LENGTH_SHORT).show(); Intent shopFragmentIntent = new Intent(getActivity(), NewBudgetTracker.class); shopFragmentIntent.putExtra(SHOP_FRAGMENT_ID, storeItemId.getId()); startActivity(shopFragmentIntent); Log.d(TAG, "onItemClick: " + date); } });
下記は、上記画面からタップされたID元にViewModelクラス→Repositoryクラス→Daoクラスを通してselect文を発行する画面です。
package com.myproject.offlinebudgettrackerappproject; import android.app.DatePickerDialog; import android.content.Intent; import android.os.Bundle; import android.text.TextUtils; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.DatePicker; import android.widget.EditText; import androidx.appcompat.app.AppCompatActivity; import androidx.lifecycle.Observer; import androidx.lifecycle.ViewModelProvider; import com.myproject.offlinebudgettrackerappproject.model.BudgetTracker; import com.myproject.offlinebudgettrackerappproject.model.BudgetTrackerViewModel; import java.util.Calendar; public class NewBudgetTracker extends AppCompatActivity { private EditText enterDate; private EditText enterStoreName; private EditText enterProductName; private EditText enterProductType; private EditText enterPrice; private Button saveInfoButton; private int shopFragmentIntentId = 0; boolean isEdit = false; private BudgetTrackerViewModel budgetTrackerViewModel; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_new_budget_tracker); enterDate = findViewById(R.id.enter_date); enterStoreName = findViewById(R.id.enter_store_name); enterProductName = findViewById(R.id.enter_product_name); enterProductType = findViewById(R.id.enter_product_type); enterPrice = findViewById(R.id.enter_price); saveInfoButton = findViewById(R.id.saveIndoButton); Calendar calendar = Calendar.getInstance(); final int year = calendar.get(Calendar.YEAR); final int month = calendar.get(Calendar.MONTH); final int day = calendar.get(Calendar.DAY_OF_MONTH); enterDate.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { DatePickerDialog datePickerDialog = new DatePickerDialog( NewBudgetTracker.this, new DatePickerDialog.OnDateSetListener() { @Override public void onDateSet(DatePicker datePicker, int year, int month, int dayOfMonth) { month = month + 1; String date = year + "-" + month + "-" + dayOfMonth; enterDate.setText(date); } }, year, month, day); datePickerDialog.show(); } }); budgetTrackerViewModel = new ViewModelProvider.AndroidViewModelFactory(NewBudgetTracker.this .getApplication()) .create(BudgetTrackerViewModel.class); Intent shopFragmentGetIntent = getIntent(); Bundle shopFragmentGetIntentBundle = shopFragmentGetIntent.getExtras(); if (shopFragmentGetIntentBundle != null) { shopFragmentIntentId = getIntent().getIntExtra(ShopFragment.SHOP_FRAGMENT_ID, 0); // shopFragmentIntentId = shopFragmentGetIntentBundle.getInt(ShopFragment.SHOP_FRAGMENT_ID); Log.d("TAG", "shopFragment: " + shopFragmentIntentId); budgetTrackerViewModel.getBudgetTrackerId(shopFragmentIntentId).observe(this, new Observer<BudgetTracker>() { @Override public void onChanged(BudgetTracker budgetTracker) { enterDate.setText(budgetTracker.getDate()); enterStoreName.setText(budgetTracker.getStoreName()); enterProductName.setText(budgetTracker.getProductName()); enterProductType.setText(budgetTracker.getProductType()); enterPrice.setText(String.valueOf(budgetTracker.getPrice())); } }); isEdit = true; } saveInfoButton.setOnClickListener(view -> { Intent replyIntent = new Intent(); if (!TextUtils.isEmpty(enterDate.getText()) && !TextUtils.isEmpty(enterStoreName.getText()) && !TextUtils.isEmpty(enterProductName.getText()) && !TextUtils.isEmpty(enterProductType.getText()) && !TextUtils.isEmpty(enterPrice.getText())) { String date = enterDate.getText().toString(); String storeName = enterStoreName.getText().toString(); String productName = enterProductName.getText().toString(); String productType = enterProductType.getText().toString(); int price = Integer.parseInt(enterPrice.getText().toString()); BudgetTracker budgetTracker = new BudgetTracker(date, storeName, productName, productType, price); budgetTrackerViewModel.insert(budgetTracker); } finish(); }); } }
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2022/04/20 13:43