java - NumberFormatException Android Java

Question

我是编码新手，所以如果这确实很明显，我深表歉意，我已经搜索了异常，但要么完全迷失/理解问题，但不知道如何解决它。

以下是库存应用程序的代码，以下是用户输入项目信息以添加到数据库的 Activity 。我相信问题出现在“saveItemCheck”方法中。 saveItemCheck 方法应确保用户已在必填字段中输入信息，如果没有显示 toast 消息，则应用程序会停止并显示 logcat 详细信息；

java.lang.NumberFormatException: empty String
        at java.lang.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1071)
        at java.lang.Float.parseFloat(Float.java:459)
        at com.example.android.inventoryapp.EditorActivity.saveItemCheck(EditorActivity.java:97)

所以，从这里，我知道问题是它不喜欢 Float 并且可能不喜欢 int 如果代码达到了那么远，但我不知道如何修复它。再次，我为我缺乏知识而道歉，我想这将是非常明显的，但在过去两周从事这个项目后我的大脑已经失去了作用。

我已经包含了整个文件以供引用，以防万一我错了或者遗漏了其他内容。

    public class EditorActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    private static final int EXISTING_INVENTORY_LOADER = 0;

    /** Content URI for the existing item (null if it's a new item) */
    private Uri mCurrentInventoryUri;

    /** EditText field to enter the item's name */
    private EditText mNameEditText;

    /** EditText field to enter the item's price */
    private EditText mPriceEditText;

    /** EditText field to enter the quantity of the item */
    private EditText mQuantityEditText;

    /** EditText field to enter the item's supplier */
    private EditText mSupplierEditText;

    /** EditText field to enter the supplier's number */
    private EditText mSupplierNumberEditText;

    private boolean mItemHasChanged = false;

    private View.OnTouchListener mTouchListener =new View.OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent motionEvent){
            mItemHasChanged = true;
            return false;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_editor);

        Intent intent = getIntent();
        mCurrentInventoryUri = intent.getData();

        if (mCurrentInventoryUri == null) {
            setTitle(getString(R.string.editor_activity_title_new_item));
            invalidateOptionsMenu();
        }else{
            setTitle(getString(R.string.editor_activity_update_an_item));
            getLoaderManager().initLoader(EXISTING_INVENTORY_LOADER, null, this);
        }

        // Find all relevant views that we will need to read user input from
        mNameEditText = (EditText) findViewById(R.id.edit_item_name);
        mPriceEditText = (EditText) findViewById(R.id.edit_item_price);
        mQuantityEditText = (EditText) findViewById(R.id.edit_item_quantity);
        mSupplierEditText = (EditText) findViewById(R.id.edit_item_supplier_name);
        mSupplierNumberEditText = (EditText) findViewById(R.id.edit_item_supplier_number);

        mNameEditText.setOnTouchListener(mTouchListener);
        mPriceEditText.setOnTouchListener(mTouchListener);
        mQuantityEditText.setOnTouchListener(mTouchListener);
        mSupplierEditText.setOnTouchListener(mTouchListener);
        mSupplierNumberEditText.setOnTouchListener(mTouchListener);

    }

    private void saveItemCheck() {
        String nameString = mNameEditText.getText().toString().trim();
        String priceString = mPriceEditText.getText().toString().trim();
        Float price = Float.parseFloat(priceString);
        String quantityString = mQuantityEditText.getText().toString().trim();
        int quantity = Integer.parseInt(quantityString);
        String supplierString = mSupplierEditText.getText().toString().trim();
        String supplierNumberString = mSupplierNumberEditText.getText().toString().trim();

        if (mCurrentInventoryUri == null &&
                TextUtils.isEmpty(nameString) && TextUtils.isEmpty(priceString) &&
                TextUtils.isEmpty(quantityString) && TextUtils.isEmpty(supplierString) &&
                TextUtils.isEmpty(supplierNumberString)) {
            return;
        }
        if (TextUtils.isEmpty(nameString) || TextUtils.isEmpty(priceString)
                || TextUtils.isEmpty(quantityString) || TextUtils.isEmpty(supplierString)
                || TextUtils.isEmpty(supplierNumberString)) {
            Toast.makeText(this, "Please fill all the starred fields to save the product",
                    Toast.LENGTH_LONG).show();
        } else {
            saveItem(nameString, price, quantity, supplierString, supplierNumberString);
        }
    }
        private void saveItem(String nameString, Float price, int quantity, String supplierString, String supplierNumberString) {
            ContentValues values = new ContentValues();
            values.put(InventoryEntry.COLUMN_ITEM_NAME, nameString);
            values.put(InventoryEntry.COLUMN_ITEM_PRICE, price);
            values.put(InventoryEntry.COLUMN_ITEM_QUANTITY, quantity);
            values.put(InventoryEntry.COLUMN_ITEM_SUPPLIER, supplierString);
            values.put(InventoryEntry.COLUMN_ITEM_NUMBER, supplierNumberString);

            if (mCurrentInventoryUri == null) {
                // This is a NEW item, so insert a new item into the provider,
                // returning the content URI for the new item.
                Uri newUri = getContentResolver().insert(InventoryEntry.CONTENT_URI, values);

                // Show a toast message depending on whether or not the insertion was successful.
                if (newUri == null) {
                    // If the new content URI is null, then there was an error with insertion.
                    Toast.makeText(this, getString(R.string.item_failed),
                            Toast.LENGTH_SHORT).show();
                } else {
                    // Otherwise, the insertion was successful and we can display a toast.
                    Toast.makeText(this, getString(R.string.item_added),
                            Toast.LENGTH_SHORT).show();
                }
            } else {
                // Otherwise this is an EXISTING item, so update the item with content URI: mCurrentInventoryUri
                // and pass in the new ContentValues. Pass in null for the selection and selection args
                // because mCurrentInventoryUri will already identify the correct row in the database that
                // we want to modify.
                int rowsAffected = getContentResolver().update(mCurrentInventoryUri, values, null, null);

                // Show a toast message depending on whether or not the update was successful.
                if (rowsAffected == 0) {
                    // If no rows were affected, then there was an error with the update.
                    Toast.makeText(this, getString(R.string.item_failed),
                            Toast.LENGTH_SHORT).show();
                } else {
                    // Otherwise, the update was successful and we can display a toast.
                    Toast.makeText(this, getString(R.string.item_added),
                            Toast.LENGTH_SHORT).show();
                }
            }
        }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu options from the res/menu/menu_editor.xml file.
        // This adds menu items to the app bar.
        getMenuInflater().inflate(R.menu.menu_editor, menu);
        return true;
    }

    /**
     * This method is called after invalidateOptionsMenu(), so that the
     * menu can be updated (some menu items can be hidden or made visible).
     */
    @Override
      public boolean onPrepareOptionsMenu(Menu menu) {
        super.onPrepareOptionsMenu(menu);
        // If this is a new item, hide the "Delete" menu item.
        if (mCurrentInventoryUri == null) {
            MenuItem menuItem = menu.findItem(R.id.action_delete);
            menuItem.setVisible(false);
            }
        return true;
        }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // User clicked on a menu option in the app bar overflow menu
        switch (item.getItemId()) {
            // Respond to a click on the "Save" menu option
            case R.id.action_save:
                // Save item to database
                saveItemCheck();
                // Exit activity
                finish();
                return true;
            // Respond to a click on the "Delete" menu option
            case R.id.action_delete:
                deleteItem();
                return true;
            // Respond to a click on the "Up" arrow button in the app bar
            case android.R.id.home:
                // If the item hasn't changed, continue with navigating up to parent activity
                // which is the {@link CatalogActivity}.
                if (!mItemHasChanged) {
                    NavUtils.navigateUpFromSameTask(EditorActivity.this);
                    return true;
                }

                // Otherwise if there are unsaved changes, setup a dialog to warn the user.
                // Create a click listener to handle the user confirming that
                // changes should be discarded.
                DialogInterface.OnClickListener discardButtonClickListener =
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                // User clicked "Discard" button, navigate to parent activity.
                                NavUtils.navigateUpFromSameTask(EditorActivity.this);
                            }
                        };

                // Show a dialog that notifies the user they have unsaved changes
                showUnsavedChangesDialog(discardButtonClickListener);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

        /**
         * This method is called when the back button is pressed.
         */
        @Override
        public void onBackPressed() {
            // If the item hasn't changed, continue with handling back button press
            if (!mItemHasChanged) {
                super.onBackPressed();
                return;
            }

            // Otherwise if there are unsaved changes, setup a dialog to warn the user.
            // Create a click listener to handle the user confirming that changes should be discarded.
            DialogInterface.OnClickListener discardButtonClickListener =
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            // User clicked "Discard" button, close the current activity.
                            finish();
                        }
                    };

            // Show dialog that there are unsaved changes
            showUnsavedChangesDialog(discardButtonClickListener);
        }

    @Override
    public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
        // Since the editor shows all pet attributes, define a projection that contains
        // all columns from the Stock table
        String[] projection = {
                InventoryEntry._ID,
                InventoryEntry.COLUMN_ITEM_NAME,
                InventoryEntry.COLUMN_ITEM_PRICE,
                InventoryEntry.COLUMN_ITEM_QUANTITY,
                InventoryEntry.COLUMN_ITEM_SUPPLIER,
                InventoryEntry.COLUMN_ITEM_NUMBER};

        // This loader will execute the ContentProvider's query method on a background thread
        return new CursorLoader(this,   // Parent activity context
                mCurrentInventoryUri,         // Query the content URI for the current item
                projection,             // Columns to include in the resulting Cursor
                null,                   // No selection clause
                null,                   // No selection arguments
                null);                  // Default sort order
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
        // Bail early if the cursor is null or there is less than 1 row in the cursor
        if (cursor == null || cursor.getCount() < 1) {
            return;
        }

        // Proceed with moving to the first row of the cursor and reading data from it
        // (This should be the only row in the cursor)
        if (cursor.moveToFirst()) {
            // Find the columns of pet attributes that we're interested in
            int nameColumnIndex = cursor.getColumnIndex(InventoryEntry.COLUMN_ITEM_NAME);
            int priceColumnIndex = cursor.getColumnIndex(InventoryEntry.COLUMN_ITEM_PRICE);
            int quantityColumnIndex = cursor.getColumnIndex(InventoryEntry.COLUMN_ITEM_QUANTITY);
            int supplierColumnIndex = cursor.getColumnIndex(InventoryEntry.COLUMN_ITEM_SUPPLIER);
            int supplierNumberColumnIndex = cursor.getColumnIndex(InventoryEntry.COLUMN_ITEM_NUMBER);

            // Extract out the value from the Cursor for the given column index
            String name = cursor.getString(nameColumnIndex);
            Float price = cursor.getFloat(priceColumnIndex);
            int quantity = cursor.getInt(quantityColumnIndex);
            String supplier = cursor.getString(supplierColumnIndex);
            String supplierNumber = cursor.getString(supplierNumberColumnIndex);

            // Update the views on the screen with the values from the database
            mNameEditText.setText(name);
            mPriceEditText.setText(Float.toString(price));
            mQuantityEditText.setText(Integer.toString(quantity));
            mSupplierEditText.setText(supplier);
            mSupplierNumberEditText.setText(supplierNumber);

        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // If the loader is invalidated, clear out all the data from the input fields.
        mNameEditText.setText("");
        mPriceEditText.setText("");
        mQuantityEditText.setText("");
        mSupplierEditText.setText("");
        mSupplierNumberEditText.setText("");
    }

    /**
     * Show a dialog that warns the user there are unsaved changes that will be lost
     * if they continue leaving the editor.
     *
     * @param discardButtonClickListener is the click listener for what to do when
     *                                   the user confirms they want to discard their changes
     */
    private void showUnsavedChangesDialog(
            DialogInterface.OnClickListener discardButtonClickListener) {
        // Create an AlertDialog.Builder and set the message, and click listeners
        // for the positive and negative buttons on the dialog.
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage(R.string.unsaved_changes_dialog_msg);
        builder.setPositiveButton(R.string.discard, discardButtonClickListener);
        builder.setNegativeButton(R.string.keep_editing, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                // User clicked the "Keep editing" button, so dismiss the dialog
                // and continue editing the item.
                if (dialog != null) {
                    dialog.dismiss();
                }
            }
        });

        // Create and show the AlertDialog
        AlertDialog alertDialog = builder.create();
        alertDialog.show();
    }

    /**
     * Perform the deletion of the pet in the database.
     */
    private void deleteItem() {
        // Only perform the delete if this is an existing item.
        if (mCurrentInventoryUri != null) {
            // Call the ContentResolver to delete the item at the given content URI.
            // Pass in null for the selection and selection args because the mCurrentPetUri
            // content URI already identifies the item that we want.
            int rowsDeleted = getContentResolver().delete(mCurrentInventoryUri, null, null);

            // Show a toast message depending on whether or not the delete was successful.
            if (rowsDeleted == 0) {
                // If no rows were deleted, then there was an error with the delete.
                Toast.makeText(this, getString(R.string.editor_delete_item_failed),
                        Toast.LENGTH_SHORT).show();
            } else {
                // Otherwise, the delete was successful and we can display a toast.
                Toast.makeText(this, getString(R.string.editor_delete_item_successful),
                        Toast.LENGTH_SHORT).show();
            }
        }
        // Close the activity
        finish();
    }
}

Answer 1

这意味着您尝试将空字符串转换为 float 。
也许在这里: float 价格 = Float.parseFloat(priceString);

因此重写为:

private void saveItemCheck() {
    String nameString = mNameEditText.getText().toString().trim();
    String priceString = mPriceEditText.getText().toString().trim();
    String quantityString = mQuantityEditText.getText().toString().trim();
    String supplierString = mSupplierEditText.getText().toString().trim();
    String supplierNumberString = mSupplierNumberEditText.getText().toString().trim();

    if (mCurrentInventoryUri == null &&
            TextUtils.isEmpty(nameString) && TextUtils.isEmpty(priceString) &&
            TextUtils.isEmpty(quantityString) && TextUtils.isEmpty(supplierString) &&
            TextUtils.isEmpty(supplierNumberString)) {
        return;
    }
    if (TextUtils.isEmpty(nameString) || TextUtils.isEmpty(priceString)
            || TextUtils.isEmpty(quantityString) || TextUtils.isEmpty(supplierString)
            || TextUtils.isEmpty(supplierNumberString)) {
        Toast.makeText(this, "Please fill all the starred fields to save the product",
                Toast.LENGTH_LONG).show();
    } else {
        Float price = Float.parseFloat(priceString);
        int quantity = Integer.parseInt(quantityString);
        saveItem(nameString, price, quantity, supplierString, supplierNumberString);
    }
}