我试过在这里找到问题，但我不能，我对android编程很新。 我发布了我的整个项目。我认为问题出在ToDoListAdapter或onActivityResult（）方法的某个地方，除了当我点击提交新项目没有显示在主屏幕上时，一切正常。我搜索了所有的论坛，尝试了使用LayoutInflater进行充气的不同方式，但我不知道出了什么问题：
ToDoListAdapter.class：
package course.labs.todomanager;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.zip.Inflater;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.RelativeLayout;
import android.widget.TextView;
import course.labs.todomanager.ToDoItem.Priority;
import course.labs.todomanager.ToDoItem.Status;
public class ToDoListAdapter extends BaseAdapter {
// List of ToDoItems
private final List<ToDoItem> mItems = new ArrayList<ToDoItem>();
private final Context mContext;
private static final String TAG = "Lab-UserInterface";
public ToDoListAdapter(Context context) {
mContext = context;
}
// Add a ToDoItem to the adapter
// Notify observers that the data set has changed
public void add(ToDoItem item) {
mItems.add(item);
notifyDataSetChanged();
}
// Clears the list adapter of all items.
public void clear(){
mItems.clear();
notifyDataSetChanged();
}
// Returns the number of ToDoItems
@Override
public int getCount() {
return mItems.size();
}
// Retrieve the number of ToDoItems
@Override
public Object getItem(int pos) {
return mItems.get(pos);
}
// Get the ID for the ToDoItem
// In this case it's just the position
@Override
public long getItemId(int pos) {
return pos;
}
//Create a View to display the ToDoItem
// at specified position in mItems
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//TODO - Get the current ToDoItem
final ToDoItem toDoItem = (ToDoItem) getItem (position);
//TODO - Inflate the View for this ToDoItem
// from todo_item.xml.
if(convertView == null){
LayoutInflater inflater =(LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.add_todo, null);
}
// RelativeLayout itemLayout = (RelativeLayout)findViewById(R.id.RelativeLayout1);<<--No need to use it..
//TODO - Fill in specific ToDoItem data
// Remember that the data that goes in this View
// corresponds to the user interface elements defined
// in the layout file
//TODO - Display Title in TextView
final TextView titleView = (TextView)convertView.findViewById(R.id.titleView);
titleView.setText(toDoItem.getTitle());
// TODO - Set up Status CheckBox
final CheckBox statusView = (CheckBox)convertView.findViewById(R.id.statusCheckBox);
statusView.setChecked(toDoItem.getStatus()==Status.DONE);
statusView.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
log("Entered onCheckedChanged()");
// TODO - Set up and implement an OnCheckedChangeListener, which
// is called when the user toggles the status checkbox
if (toDoItem.getStatus().equals(Status.DONE))
{
toDoItem.setStatus(Status.NOTDONE); //Change it
}
else
{
toDoItem.setStatus(Status.DONE); //Change it
}
}
});
//TODO - Display Priority in a TextView
final TextView priorityView = (TextView)convertView.findViewById(R.id.priorityView);
priorityView.setText(toDoItem.getPriority().toString());
// TODO - Display Time and Date.
// Hint - use ToDoItem.FORMAT.format(toDoItem.getDate()) to get date and time String
final TextView dateView = (TextView)convertView.findViewById(R.id.dateView);
dateView.setText(ToDoItem.FORMAT.format(toDoItem.getDate()));
// Return the View you just created
return convertView;
}
private void log(String msg) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i(TAG, msg);
}
}
ToDoManagerActivity.class
package course.labs.todomanager;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.text.ParseException;
import java.util.Date;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import course.labs.todomanager.ToDoItem.Priority;
import course.labs.todomanager.ToDoItem.Status;
public class ToDoManagerActivity extends ListActivity {
// Add a ToDoItem Request Code
private static final int ADD_TODO_ITEM_REQUEST = 0;
private static final String FILE_NAME = "TodoManagerActivityData.txt";
private static final String TAG = "Lab-UserInterface";
// IDs for menu items
private static final int MENU_DELETE = Menu.FIRST;
private static final int MENU_DUMP = Menu.FIRST + 1;
ToDoListAdapter mAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a new TodoListAdapter for this ListActivity's ListView
mAdapter = new ToDoListAdapter(getApplicationContext());
// Put divider between ToDoItems and FooterView
getListView().setFooterDividersEnabled(true);
//TODO - Inflate footerView for footer_view.xml file
LayoutInflater inflator = LayoutInflater.from(ToDoManagerActivity.this);
TextView footerView = (TextView)inflator.inflate(R.layout.footer_view, null);
//TODO - Add footerView to ListView
getListView().addFooterView(footerView);
footerView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
log("Entered footerView.OnClickListener.onClick()");
//TODO - Attach Listener to FooterView. Implement onClick().
Intent intent = new Intent(getBaseContext(), AddToDoActivity.class);
startActivityForResult(intent, ADD_TODO_ITEM_REQUEST);
}
});
//TODO - Attach the adapter to this ListActivity's ListView
getListView().setAdapter(mAdapter);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
log("Entered onActivityResult()");
// TODO - Check result code and request code.
// If user submitted a new ToDoItem
// Create a new ToDoItem from the data Intent
// and then add it to the adapter
if (requestCode == 1) {
if (resultCode == RESULT_OK)
{
ToDoItem toDo = new ToDoItem(data);
mAdapter.add(toDo);
}
else
{
}
}
}
// Do not modify below here
@Override
public void onResume() {
super.onResume();
// Load saved ToDoItems, if necessary
if (mAdapter.getCount() == 0)
loadItems();
}
@Override
protected void onPause() {
super.onPause();
// Save ToDoItems
saveItems();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(Menu.NONE, MENU_DELETE, Menu.NONE, "Delete all");
menu.add(Menu.NONE, MENU_DUMP, Menu.NONE, "Dump to log");
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case MENU_DELETE:
mAdapter.clear();
return true;
case MENU_DUMP:
dump();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void dump() {
for (int i = 0; i < mAdapter.getCount(); i++) {
String data = ((ToDoItem) mAdapter.getItem(i)).toLog();
log("Item " + i + ": " + data.replace(ToDoItem.ITEM_SEP, ","));
}
}
// Load stored ToDoItems
private void loadItems() {
BufferedReader reader = null;
try {
FileInputStream fis = openFileInput(FILE_NAME);
reader = new BufferedReader(new InputStreamReader(fis));
String title = null;
String priority = null;
String status = null;
Date date = null;
while (null != (title = reader.readLine())) {
priority = reader.readLine();
status = reader.readLine();
date = ToDoItem.FORMAT.parse(reader.readLine());
mAdapter.add(new ToDoItem(title, Priority.valueOf(priority),
Status.valueOf(status), date));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
} finally {
if (null != reader) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
// Save ToDoItems to file
private void saveItems() {
PrintWriter writer = null;
try {
FileOutputStream fos = openFileOutput(FILE_NAME, MODE_PRIVATE);
writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
fos)));
for (int idx = 0; idx < mAdapter.getCount(); idx++) {
writer.println(mAdapter.getItem(idx));
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != writer) {
writer.close();
}
}
}
private void log(String msg) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i(TAG, msg);
}
}
AddToDoActivity.class：
package course.labs.todomanager;
import java.util.Calendar;
import java.util.Date;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.TimePickerDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.widget.TimePicker;
import course.labs.todomanager.ToDoItem.Priority;
import course.labs.todomanager.ToDoItem.Status;
public class AddToDoActivity extends Activity {
// 7 days in milliseconds - 7 * 24 * 60 * 60 * 1000
private static final int SEVEN_DAYS = 604800000;
private static final String TAG = "Lab-UserInterface";
private static String timeString;
private static String dateString;
private static TextView dateView;
private static TextView timeView;
private Date mDate;
private RadioGroup mPriorityRadioGroup;
private RadioGroup mStatusRadioGroup;
private EditText mTitleText;
private RadioButton mDefaultStatusButton;
private RadioButton mDefaultPriorityButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_todo);
mTitleText = (EditText) findViewById(R.id.title);
mDefaultStatusButton = (RadioButton) findViewById(R.id.statusNotDone);
mDefaultPriorityButton = (RadioButton) findViewById(R.id.medPriority);
mPriorityRadioGroup = (RadioGroup) findViewById(R.id.priorityGroup);
mStatusRadioGroup = (RadioGroup) findViewById(R.id.statusGroup);
dateView = (TextView) findViewById(R.id.date);
timeView = (TextView) findViewById(R.id.time);
// Set the default date and time
setDefaultDateTime();
// OnClickListener for the Date button, calls showDatePickerDialog() to show
// the Date dialog
final Button datePickerButton = (Button) findViewById(R.id.date_picker_button);
datePickerButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
showDatePickerDialog();
}
});
// OnClickListener for the Time button, calls showTimePickerDialog() to show
// the Time Dialog
final Button timePickerButton = (Button) findViewById(R.id.time_picker_button);
timePickerButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
showTimePickerDialog();
}
});
// OnClickListener for the Cancel Button,
final Button cancelButton = (Button) findViewById(R.id.cancelButton);
cancelButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
log("Entered cancelButton.OnClickListener.onClick()");
//TODO - Implement onClick().
Intent intent = null;
setResult(Activity.RESULT_CANCELED, intent);
finish();
}
});
//OnClickListener for the Reset Button
final Button resetButton = (Button) findViewById(R.id.resetButton);
resetButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
log("Entered resetButton.OnClickListener.onClick()");
//TODO - Reset data fields to default values
mTitleText.setText("");
mDefaultStatusButton.setChecked(true);
mDefaultPriorityButton.setChecked(true);
setDefaultDateTime();
}
});
// OnClickListener for the Submit Button
// Implement onClick().
final Button submitButton = (Button) findViewById(R.id.submitButton);
submitButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
log("Entered submitButton.OnClickListener.onClick()");
// Gather ToDoItem data
//TODO - Get Priority
Priority priority = getPriority();
//TODO - Get Status
Status status = getStatus();
//TODO - Title
String titleString = mTitleText.getText().toString();
// Date
String fullDate = dateString + " " + timeString;
// Package ToDoItem data into an Intent
Intent dataIntent = new Intent();
ToDoItem.packageIntent(dataIntent, titleString, priority, status, fullDate);
//TODO - return data Intent and finish
setResult(Activity.RESULT_OK, dataIntent);
finish();
}
});
}
// Do not modify below here
// Use this method to set the default date and time
private void setDefaultDateTime() {
// Default is current time + 7 days
mDate = new Date();
mDate = new Date(mDate.getTime() + SEVEN_DAYS);
Calendar c = Calendar.getInstance();
c.setTime(mDate);
setDateString(c.get(Calendar.YEAR), c.get(Calendar.MONTH),
c.get(Calendar.DAY_OF_MONTH));
dateView.setText(dateString);
setTimeString(c.get(Calendar.HOUR_OF_DAY), c.get(Calendar.MINUTE),
c.get(Calendar.MILLISECOND));
timeView.setText(timeString);
}
private static void setDateString(int year, int monthOfYear, int dayOfMonth) {
// Increment monthOfYear for Calendar/Date -> Time Format setting
monthOfYear++;
String mon = "" + monthOfYear;
String day = "" + dayOfMonth;
if (monthOfYear < 10)
mon = "0" + monthOfYear;
if (dayOfMonth < 10)
day = "0" + dayOfMonth;
dateString = year + "-" + mon + "-" + day;
}
private static void setTimeString(int hourOfDay, int minute, int mili) {
String hour = "" + hourOfDay;
String min = "" + minute;
if (hourOfDay < 10)
hour = "0" + hourOfDay;
if (minute < 10)
min = "0" + minute;
timeString = hour + ":" + min + ":00";
}
private Priority getPriority() {
switch (mPriorityRadioGroup.getCheckedRadioButtonId()) {
case R.id.lowPriority: {
return Priority.LOW;
}
case R.id.highPriority: {
return Priority.HIGH;
}
default: {
return Priority.MED;
}
}
}
private Status getStatus() {
switch (mStatusRadioGroup.getCheckedRadioButtonId()) {
case R.id.statusDone: {
return Status.DONE;
}
default: {
return Status.NOTDONE;
}
}
}
// DialogFragment used to pick a ToDoItem deadline date
public static class DatePickerFragment extends DialogFragment implements
DatePickerDialog.OnDateSetListener {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Use the current date as the default date in the picker
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = c.get(Calendar.DAY_OF_MONTH);
// Create a new instance of DatePickerDialog and return it
return new DatePickerDialog(getActivity(), this, year, month, day);
}
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
setDateString(year, monthOfYear, dayOfMonth);
dateView.setText(dateString);
}
}
// DialogFragment used to pick a ToDoItem deadline time
public static class TimePickerFragment extends DialogFragment implements
TimePickerDialog.OnTimeSetListener {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Use the current time as the default values for the picker
final Calendar c = Calendar.getInstance();
int hour = c.get(Calendar.HOUR_OF_DAY);
int minute = c.get(Calendar.MINUTE);
// Create a new instance of TimePickerDialog and return
return new TimePickerDialog(getActivity(), this, hour, minute,
true);
}
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
setTimeString(hourOfDay, minute, 0);
timeView.setText(timeString);
}
}
private void showDatePickerDialog() {
DialogFragment newFragment = new DatePickerFragment();
newFragment.show(getFragmentManager(), "datePicker");
}
private void showTimePickerDialog() {
DialogFragment newFragment = new TimePickerFragment();
newFragment.show(getFragmentManager(), "timePicker");
}
private void log(String msg) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i(TAG, msg);
}
}
logcat的：
03-01 11:18:16.638: I/Lab-UserInterface(2179): Entered footerView.OnClickListener.onClick()
03-01 11:18:16.828: D/dalvikvm(2179): GC_FOR_ALLOC freed 305K, 12% free 4018K/4544K, paused 6ms, total 7ms
03-01 11:18:27.458: I/Lab-UserInterface(2179): Entered submitButton.OnClickListener.onClick()
03-01 11:18:28.038: I/Lab-UserInterface(2179): Entered onActivityResult()
03-01 11:18:28.048: I/Choreographer(2179): Skipped 57 frames! The application may be doing too much work on its main thread.
03-01 11:18:28.408: D/AndroidRuntime(2179): Shutting down VM
03-01 11:18:28.418: W/dalvikvm(2179): threadid=1: thread exiting with uncaught exception (group=0xb0f29648)
03-01 11:18:28.548: D/dalvikvm(2179): GC_FOR_ALLOC freed 71K, 7% free 4470K/4760K, paused 85ms, total 86ms
03-01 11:18:28.548: E/AndroidRuntime(2179): FATAL EXCEPTION: main
03-01 11:18:28.548: E/AndroidRuntime(2179): java.lang.NullPointerException
03-01 11:18:28.548: E/AndroidRuntime(2179): at course.labs.todomanager.ToDoListAdapter.getView(ToDoListAdapter.java:114)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.AbsListView.obtainView(AbsListView.java:2177)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.ListView.makeAndAddView(ListView.java:1840)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.ListView.fillSpecific(ListView.java:1321)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.ListView.layoutChildren(ListView.java:1633)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.AbsListView.onLayout(AbsListView.java:2012)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.View.layout(View.java:14289)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewGroup.layout(ViewGroup.java:4562)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.View.layout(View.java:14289)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewGroup.layout(ViewGroup.java:4562)
03-01 11:18:28.548: E/AndroidRuntime(2179): at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:349)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.View.layout(View.java:14289)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewGroup.layout(ViewGroup.java:4562)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.View.layout(View.java:14289)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewGroup.layout(ViewGroup.java:4562)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1976)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1730)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.Choreographer.doFrame(Choreographer.java:532)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.os.Handler.handleCallback(Handler.java:730)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.os.Handler.dispatchMessage(Handler.java:92)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.os.Looper.loop(Looper.java:137)
03-01 11:18:28.548: E/AndroidRuntime(2179): at android.app.ActivityThread.main(ActivityThread.java:5103)
03-01 11:18:28.548: E/AndroidRuntime(2179): at java.lang.reflect.Method.invokeNative(Native Method)
03-01 11:18:28.548: E/AndroidRuntime(2179): at java.lang.reflect.Method.invoke(Method.java:525)
03-01 11:18:28.548: E/AndroidRuntime(2179): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-01 11:18:28.548: E/AndroidRuntime(2179): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-01 11:18:28.548: E/AndroidRuntime(2179): at dalvik.system.NativeStart.main(Native Method)
03-01 11:18:33.448: I/Process(2179): Sending signal. PID: 2179 SIG: 9
答案 0 :(得分：1)
更改此
if (requestCode == 1) {
到
if (requestCode == ADD_TODO_ITEM_REQUEST) {
根据他们所说的实施
，您需要更改适配器getview（）todo_item.xml
//TODO - Inflate the View for this ToDoItem
// from todo_item.xml.
if(convertView == null){
// rest of the code
convertView = inflater.inflate(R.layout.todo_item, null);
}