这些是我得到的错误。
09-23 04:24:04.712: E/AndroidRuntime(332): FATAL EXCEPTION: main
09-23 04:24:04.712: E/AndroidRuntime(332): java.lang.RuntimeException: Unable to resume activity {ph.cksc.edu.softeng.financialsecretary/ph.cksc.edu.softeng.financialsecretary.BudgetsEditor}: java.lang.NullPointerException
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2120)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2135)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1668)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.os.Handler.dispatchMessage(Handler.java:99)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.os.Looper.loop(Looper.java:123)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.main(ActivityThread.java:3683)
09-23 04:24:04.712: E/AndroidRuntime(332): at java.lang.reflect.Method.invokeNative(Native Method)
09-23 04:24:04.712: E/AndroidRuntime(332): at java.lang.reflect.Method.invoke(Method.java:507)
09-23 04:24:04.712: E/AndroidRuntime(332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
09-23 04:24:04.712: E/AndroidRuntime(332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
09-23 04:24:04.712: E/AndroidRuntime(332): at dalvik.system.NativeStart.main(Native Method)
09-23 04:24:04.712: E/AndroidRuntime(332): Caused by: java.lang.NullPointerException
09-23 04:24:04.712: E/AndroidRuntime(332): at ph.cksc.edu.softeng.financialsecretary.BudgetsEditor.onResume(BudgetsEditor.java:141)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1150)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.Activity.performResume(Activity.java:3832)
09-23 04:24:04.712: E/AndroidRuntime(332): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2110)
09-23 04:24:04.712: E/AndroidRuntime(332): ... 12 more
这是 BudgetsEditor 的代码：
public class BudgetsEditor extends Activity {
private static final String TAG = "BudgetsEditor";
private static final String[] PROJECTION = new String[] { Budgets._ID, // 0
Budgets.TITLE, // 1
Budgets.AMOUNT, // 2
Budgets.ROLLOVER_FLAG, // 3
Budgets.START_DATE // 4
};
/** The index of the budget column */
private static final int PROJECTION_INDEX_TITLE = 1;
private static final int PROJECTION_INDEX_AMOUNT = 2;
private static final int PROJECTION_INDEX_ROLLOVER_FLAG = 3;
private static final int PROJECTION_INDEX_START_DATE = 4;
// Identifiers for our menu items.
private static final int REVERT_ID = Menu.FIRST;
private static final int DISCARD_ID = Menu.FIRST + 1;
private static final int DELETE_ID = Menu.FIRST + 2;
private static final int SAVE_ID = Menu.FIRST + 3;
// The different distinct states the activity can be run in.
private static final int STATE_EDIT = 0;
private static final int STATE_INSERT = 1;
private int mState;
private Uri mUri;
private Cursor mCursor;
private EditText mTitle;
private EditText mAmount;
private ToggleButton mRollover;
private DateControlSet mStartDate;
private String mOriginalTitle;
private float mOriginalAmount;
private int mOriginalRollover;
private long mOriginalStartDate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Intent intent = getIntent();
final String action = intent.getAction();
if (Intent.ACTION_EDIT.equals(action)) {
// Requested to edit: set that state, and the data being edited.
mState = STATE_EDIT;
mUri = intent.getData();
} else if (Intent.ACTION_INSERT.equals(action)) {
// Requested to insert: set that state, and create a new entry
// in the container.
mState = STATE_INSERT;
mUri = getContentResolver().insert(intent.getData(), null);
// If we were unable to create a new budget, then just finish
// this activity. A RESULT_CANCELED will be sent back to the
// original activity if they requested a result.
if (mUri == null) {
Log.e(TAG, "Failed to insert new budget into " + getIntent().getData());
finish();
return;
}
// The new entry was created, so assume all will end well and
// set the result to be returned.
setResult(RESULT_OK, (new Intent()).setAction(mUri.toString()));
} else {
// Whoops, unknown action! Bail.
Log.e(TAG, "Unknown action, exiting");
finish();
return;
}
setContentView(R.layout.budgetslist_editor);
mTitle = (EditText) findViewById(R.id.budget_title);
mAmount = (EditText) findViewById(R.id.budget_amount);
mStartDate = new DateControlSet(this, R.id.budget_start_date, R.id.budget_start_time);
mCursor = managedQuery(mUri, PROJECTION, null, null, null);
// If an instance of this activity had previously stopped, we can
// get the original text it started with.
if (savedInstanceState != null) {
mOriginalTitle = savedInstanceState.getString(BudgetsPage.Budgets.TITLE);
mOriginalAmount = savedInstanceState.getFloat(BudgetsPage.Budgets.AMOUNT);
mOriginalRollover = savedInstanceState.getInt(BudgetsPage.Budgets.ROLLOVER_FLAG);
mOriginalStartDate = savedInstanceState.getLong(BudgetsPage.Budgets.START_DATE);
}
}
@Override
protected void onResume() {
super.onResume();
// If we didn't have any trouble retrieving the data, it is now
// time to get at the stuff.
if (mCursor != null) {
// Make sure we are at the one and only row in the cursor.
mCursor.moveToFirst();
// Modify our overall title depending on the mode we are running in.
if (mState == STATE_EDIT) {
setTitle(getText(R.string.title_edit));
} else if (mState == STATE_INSERT) {
setTitle(getText(R.string.title_create));
}
// This is a little tricky: we may be resumed after previously being
// paused/stopped. We want to put the new text in the text view,
// but leave the user where they were (retain the cursor position
// etc). This version of setText does that for us.
String title = mCursor.getString(PROJECTION_INDEX_TITLE);
float amount = mCursor.getFloat(PROJECTION_INDEX_AMOUNT);
int rollover = mCursor.getInt(PROJECTION_INDEX_ROLLOVER_FLAG);
long startDate = mCursor.getLong(PROJECTION_INDEX_START_DATE);
mTitle.setTextKeepState(title);
mAmount.setText(String.valueOf(amount));
mRollover.setChecked(rollover == 1);
mStartDate.setDate(startDate);
// If we hadn't previously retrieved the original text, do so
// now. This allows the user to revert their changes.
if (mOriginalTitle == null) {
mOriginalTitle = title;
}
if (mOriginalAmount == 0) {
mOriginalAmount = amount;
}
if (mOriginalRollover == 0) {
mOriginalRollover = rollover;
}
if (mOriginalStartDate == 0) {
mOriginalStartDate = startDate;
}
} else {
setTitle(getText(R.string.error_title));
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
// Save away the original text, so we still have it if the activity
// needs to be killed while paused.
outState.putString(BudgetsPage.Budgets.TITLE, mOriginalTitle);
outState.putFloat(BudgetsPage.Budgets.AMOUNT, mOriginalAmount);
outState.putInt(BudgetsPage.Budgets.ROLLOVER_FLAG, mOriginalRollover);
outState.putLong(BudgetsPage.Budgets.START_DATE, mOriginalStartDate);
}
@Override
protected void onPause() {
super.onPause();
// The user is going somewhere else, so make sure their current
// changes are safely saved away in the provider. We don't need
// to do this if only editing.
if (mCursor != null) {
final String title = mTitle.getText().toString();
// If this activity is finished, and there is no text, then we
// do something a little special: simply delete the budget entry.
// Account that we do this both for editing and inserting... it
// would be reasonable to only do it when inserting.
if (isFinishing() && TextUtils.isEmpty(title)) {
setResult(RESULT_CANCELED);
deleteAccount();
} else {
saveAccount();
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
// Build the menus that are shown when editing.
menu.add(0, SAVE_ID, 0, R.string.menu_save).setShortcut('0', 's').setIcon(android.R.drawable.ic_menu_save);
if (mState == STATE_EDIT) {
menu.add(0, REVERT_ID, 0, R.string.menu_revert).setShortcut('1', 'r')
.setIcon(android.R.drawable.ic_menu_revert);
menu.add(0, DELETE_ID, 0, R.string.menu_delete).setShortcut('2', 'd')
.setIcon(android.R.drawable.ic_menu_delete);
// Build the menus that are shown when inserting.
} else {
menu.add(0, DISCARD_ID, 0, R.string.menu_discard).setShortcut('1', 'd')
.setIcon(android.R.drawable.ic_menu_delete);
}
// If we are working on a full budget, then append to the
// menu items for any other activities that can do stuff with it
// as well. This does a query on the system for any activities that
// implement the ALTERNATIVE_ACTION for our data, adding a menu item
// for each one that is found.
Intent intent = new Intent(null, getIntent().getData());
intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
menu.addIntentOptions(Menu.CATEGORY_ALTERNATIVE, 0, 0, new ComponentName(this, BudgetsEditor.class), null,
intent, 0, null);
return true;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
final String title = mTitle.getText().toString();
menu.findItem(SAVE_ID).setEnabled(isAccountChanged() && !TextUtils.isEmpty(title));
if (mState == STATE_EDIT) {
menu.findItem(REVERT_ID).setEnabled(isAccountChanged());
}
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle all of the possible menu actions.
switch (item.getItemId()) {
case DELETE_ID:
deleteAccount();
finish();
break;
case DISCARD_ID:
cancelAccount();
setResult(RESULT_CANCELED);
finish();
break;
case REVERT_ID:
cancelAccount();
setResult(RESULT_CANCELED);
finish();
break;
case SAVE_ID:
saveAccount();
finish();
break;
}
return super.onOptionsItemSelected(item);
}
private boolean isAccountChanged() {
final float amount = getNewAccountAmount();
final String title = mTitle.getText().toString();
final int rollover = mRollover.isChecked() ? 1 : 0;
final long startDate = mStartDate.getDate().getTime();
return !title.equals(mOriginalTitle) || amount != mOriginalAmount || rollover != mOriginalRollover
|| startDate != mOriginalStartDate;
}
private float getNewAccountAmount() {
float amount;
try {
amount = Float.parseFloat(mAmount.getText().toString());
} catch (Exception e) {
amount = 0;
}
return amount;
}
/**
* Take care of canceling work on a budget. Deletes the budget if we had created it, otherwise reverts to the
* original text.
*/
private final void cancelAccount() {
if (mCursor != null) {
if (mState == STATE_EDIT) {
// Put the original budget text back into the database
mCursor.close();
mCursor = null;
if (isAccountChanged()) {
ContentValues values = new ContentValues();
values.put(Budgets.TITLE, mOriginalTitle);
values.put(Budgets.AMOUNT, mOriginalAmount);
values.put(Budgets.ROLLOVER_FLAG, mOriginalRollover);
values.put(Budgets.START_DATE, mOriginalStartDate);
getContentResolver().update(mUri, values, null, null);
}
} else if (mState == STATE_INSERT) {
// We inserted an empty budget, make sure to delete it
deleteAccount();
}
}
}
private void saveAccount() {
final float amount = getNewAccountAmount();
ContentValues values = new ContentValues();
values.put(Budgets.TITLE, mTitle.getText().toString());
values.put(Budgets.AMOUNT, amount);
values.put(Budgets.ROLLOVER_FLAG, mRollover.isChecked() ? 1 : 0);
values.put(Budgets.START_DATE, mStartDate.getDate().getTime());
getContentResolver().update(mUri, values, null, null);
}
/**
* Take care of deleting a budget. Simply deletes the entry.
*/
private final void deleteAccount() {
if (mCursor != null) {
mCursor.close();
mCursor = null;
getContentResolver().delete(mUri, null, null);
mTitle.setText("");
}
}
}