本文介绍了java.lang.NullPointerException 显示在 mBoundService.setAlarm(c);的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想在用户选择某个日期时提醒他.我在 here 找到了一个例子，但我得到一个 NullPointerException.
I want to remind the user when he selected some date. I found an example for a remainder here but I got a NullPointerException.
package com.example.eventremainder;
import java.util.Calendar;
import com.example.eventremainder.R;
import com.example.eventremainder.Service.ScheduleClient;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.provider.Contacts;
import android.provider.ContactsContract;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class AddEventActivity extends Activity{
private EditText nameEditText,phoneet;
TextView dobm;
private DatePicker datePicker;
private Button ok,browse;
private String checkedevent;
private Spinner spinner;
private ScheduleClient scheduleClient;
private static final String[] arrayString={"BirthDay","MarriageDay"};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.selectevent);
nameEditText=(EditText)findViewById(R.id.editText1);
phoneet=(EditText)findViewById(R.id.phneno);
dobm=(TextView)findViewById(R.id.dobm);
datePicker=(DatePicker)findViewById(R.id.scheduleTimePicker);
spinner=(Spinner)findViewById(R.id.spinner1);
ok=(Button)findViewById(R.id.ok);
browse=(Button)findViewById(R.id.browse);
ok.setEnabled(false);
scheduleClient=new ScheduleClient(AddEventActivity.this);
scheduleClient.doBindService();
}
public void onResume()
{
super.onResume();
nameEditText.addTextChangedListener(tw);
dialogBox();
}
TextWatcher tw=new TextWatcher() {
public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
if(String.valueOf(arg0).equals(""))
{
ok.setEnabled(false);
}
else{
ok.setEnabled(true);
}
}
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
}
public void afterTextChanged(Editable arg0) {
if(!nameEditText.getText().toString().equals("")){
ok.setEnabled(true);
}
}
};
public void dialogBox()
{
ArrayAdapter<String > arrayAdapter=new ArrayAdapter<String>(AddEventActivity.this, android.R.layout.simple_dropdown_item_1line, arrayString);
spinner.setAdapter(arrayAdapter);
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
checkedevent=arrayString[arg2];
}
public void onNothingSelected(AdapterView<?> arg0) {
}
});
browse.setClickable(true);
ok.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
SQLiteDatabase sqLiteDatabase=null;
sqLiteDatabase=openOrCreateDatabase("eventremainder", 0 ,null);
String checkedname="---";
String phone="--";
int day=0,month=0,year;
checkedname=nameEditText.getText().toString().trim();
day=datePicker.getDayOfMonth();
year=datePicker.getYear();
month=datePicker.getMonth();
String month2=month(month);
String date=""+day+"-"+(month2);
Calendar c=Calendar.getInstance();
c.set(year, month, day);
c.set(Calendar.HOUR_OF_DAY, 0);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
// Ask our service to set an alarm for that date, this activity talks to the client that talks to the service
scheduleClient.setAlarmForNotification(c);
try{
String selection="name=? and event=? and day=? and month=?";
String[] whereArgs1={checkedname,checkedevent,""+day,month2};
Cursor cursor=sqLiteDatabase.query("eventstable", null, selection, whereArgs1, null, null, null);
if(cursor.moveToNext())
{
throw new IndexOutOfBoundsException();
}
else
{
ContentValues cv=new ContentValues();
cv.put("name", checkedname);
cv.put("event", checkedevent);
cv.put("day",day);
cv.put("month", month2);
cv.put("monthint", month);
cv.put("year", year);
cv.put("phone_no",phone);
nameEditText.setText("");
phoneet.setText("");
long l=sqLiteDatabase.insert("eventstable", null, cv);
if(l!=-1l)
{
Toast.makeText(getApplicationContext(), checkedname + checkedevent + " Added " , Toast.LENGTH_LONG).show();
switchToTab(checkedevent);
}
}
}
catch (IndexOutOfBoundsException e) {
nameEditText.setError("These Details are already exists");
}
finally{
sqLiteDatabase.close();
}
}
});
}
public String month(int month)
{
String month1=null;
switch (month) {
case 0:month1="Jan";
break;
case 1:month1="Feb";
break;
case 2:month1="Mar";
break;
case 3:month1="Apr";
break;
case 4:month1="May";
break;
case 5:month1="Jun";
break;
case 6:month1="Jul";
break;
case 7:month1="Aug";
break;
case 8:month1="Sep";
break;
case 9:month1="Oct";
break;
case 10:month1="Nov";
break;
case 11:month1="Dec";
break;
}
return month1;
}
public void browsemethod(View arg0) {
Intent intent =new Intent(getApplicationContext(), ContactsListActivity.class);
startActivityForResult(intent, 1);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(resultCode==RESULT_OK && requestCode==1){
String name = data.getStringExtra("name");
String phone=data.getStringExtra("phonenumber");
tw.onTextChanged(name, 5, 5, 5);
nameEditText.setText(name);
phoneet.setText(phone);
}
}
public boolean onKeyDown(int keyCode,KeyEvent event)
{
super.onKeyDown(keyCode, event);
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
AlertDialog.Builder alertdialogbuilder=new AlertDialog.Builder(AddEventActivity.this);
alertdialogbuilder.setTitle("Do you want to exist from application");
alertdialogbuilder.setPositiveButton("yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
alertdialogbuilder.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
alertdialogbuilder.create();
alertdialogbuilder.show();
return true;
default:
break;
}
return false;
}
public void switchToTab(String tab)
{
TabMainActivity tabMainActivity=(TabMainActivity) this.getParent();
if(tab.equalsIgnoreCase("BirthDay"))
{
tabMainActivity.switchTab(0);
}
else {
if(tab.equalsIgnoreCase("MarriageDay"))
{
tabMainActivity.switchTab(1);
}
}
}
}
</b>
another class i ussed is scheduleclient
<b>
package com.example.eventremainder.Service;
import java.util.Calendar;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
/**
* This is our service client, it is the 'middle-man' between the
* service and any activity that wants to connect to the service
*
* @author paul.blundell
*/
public class ScheduleClient {
// The hook into our service
private ScheduleService mBoundService;
// The context to start the service in
private Context mContext;
// A flag if we are connected to the service or not
private boolean mIsBound;
public ScheduleClient(Context context) {
mContext = context;
}
/**
* Call this to connect your activity to your service
*/
public void doBindService() {
// Establish a connection with our service
mContext.bindService(new Intent(mContext, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
/**
* When you attempt to connect to the service, this connection will be called with the result.
* If we have successfully connected we instantiate our service object so that we can call methods on it.
*/
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
// This is called when the connection with our service has been established,
// giving us the service object we can use to interact with our service.
mBoundService = ((ScheduleService.ServiceBinder) service).getService();
}
public void onServiceDisconnected(ComponentName className) {
mBoundService = null;
}
};
/**
* Tell our service to set an alarm for the given date
* @param c a date to set the notification for
*/
public void setAlarmForNotification(Calendar c){
mBoundService.setAlarm(c);
}
/**
* When you have finished with the service call this method to stop it
* releasing your connection and resources
*/
public void doUnbindService() {
if (mIsBound) {
// Detach our existing connection.
mContext.unbindService(mConnection);
mIsBound = false;
}
}
}
它在 mBoundService.setAlarm(c) 处显示空指针异常.
It was showing null pointer exception at mBoundService.setAlarm(c).
推荐答案
我也面临同样的问题.. 我出于某种原因在 onCreate 方法中调用了它..但是当我从其他事件调用它时，它工作正常..我知道，我迟到了，但这可能是一个可以帮助他人的解决方案
I was also facing same problem.. I had called it in onCreate method for some reason..but when I called it from other events then its works fine..I know, I am late but this can be a solution that can help others
这篇关于java.lang.NullPointerException 显示在 mBoundService.setAlarm(c);的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！