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();
}
}
最佳答案
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);
}
}
关于java - NumberFormatException Android Java，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51245207/