使用这个简单的函数我想将记录保存到数据库中，但是我收到了这个错误：
java.lang.NullPointerException
这一行：
SQLiteDatabase db = this.getWritableDatabase();
我的完整DatabaseHandler类：
public class DatabaseHandler extends SQLiteOpenHelper{
private static String DB_PATH = "";
private static final String DATABASE_NAME = "tsms";
private static String RECEIVE_FIELDS_TABLE = "ReceiveFields";
private static final String COLUMN_ID = "id";
private static final String COLUMN_LASTID = "lastId";
private static final String COLUMN_SMSNUMBER = "smsNumber";
private static final String COLUMN_MOBILENUMBER = "mobileNumber";
private static final String COLUMN_SENDERNAME = "senderName";
private static final String COLUMN_SMSBODY = "smsBody";
private static final String COLUMN_RECEIVEDATE = "receiveDate";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase mDataBase;
private static final String DATABASE_CREATE = "CREATE TABLE " + RECEIVE_FIELDS_TABLE + "("
+ COLUMN_ID + " INTEGER NOT NULL UNIQUE , "
+ COLUMN_LASTID + " INTEGER NOT NULL UNIQUE , "
+ COLUMN_SMSNUMBER + " INTEGER NOT NULL UNIQUE , "
+ COLUMN_MOBILENUMBER + " INTEGER NOT NULL , "
+ COLUMN_SENDERNAME + " VARCHAR NOT NULL , "
+ COLUMN_SMSBODY + " TEXT NOT NULL check(typeof(" + COLUMN_SMSBODY + ") = 'text') , "
+ COLUMN_RECEIVEDATE + " DATETIME NOT NULL , PRIMARY KEY (" + COLUMN_ID + ", " + COLUMN_LASTID + ", " + COLUMN_SMSNUMBER + "))";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + RECEIVE_FIELDS_TABLE);
// Create tables again
onCreate(sqLiteDatabase);
}
// Adding new fields
public void addToReceived(ReceiveFields fields) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COLUMN_LASTID, fields.getLastId()); // ReceiveFields last ID
values.put(COLUMN_MOBILENUMBER, fields.getMobileNumber()); // ReceiveFields Mobile Number
values.put(COLUMN_SENDERNAME, fields.getSenderName()); // ReceiveFields Mobile Number
values.put(COLUMN_SMSBODY, fields.getSmsBody()); // ReceiveFields Mobile Number
values.put(COLUMN_SMSNUMBER, fields.getSmsNumber()); // ReceiveFields Mobile Number
values.put(COLUMN_MOBILENUMBER, fields.getMobileNumber()); // ReceiveFields Mobile Number
values.put(COLUMN_RECEIVEDATE, String.valueOf(fields.getReceiveDate())); // ReceiveFields Mobile Number
// Inserting Row
db.insert(RECEIVE_FIELDS_TABLE, null, values);
db.close(); // Closing database connection
}
}
致电和使用：
DatabaseHandler db = new DatabaseHandler(context);
db.addToReceived(new ReceiveFields(
Long.valueOf(str1[0]),
str1[1],
str1[2],
URLDecoder.decode(str1[3], "UTF-8"),
URLDecoder.decode(str1[4], "UTF-8"),
WSDLHelper.convertDate(str1[5])));
更新帖子
TSMS类，在数据库中使用save方法：
public class TSMS {
private User user;
public SoapObject SoapObjectRequest;
private Context context;
public TSMS(User user) {
this.user = user;
}
public Boolean checkUserAuth() throws TException{
SoapObject request = new SoapObject(Strings.URL_TSMS , Strings.NAME_METHOD_IS_FROM_USERS);
this.SoapObjectRequest = request;
request.addProperty("userName", this.user.userName);
request.addProperty("passWord", this.user.passWord);
LoginFields loginSoapParser = SoapParser(WSDLHelper.convert1(WSDLHelper.call(request)));
if ( loginSoapParser.ckeckAuth){
return true;
}
else{
return false;
}
}
public LoginFields SoapParser(String result){
String receiveResult = result;
String split[] = result.split(",");
LoginFields loginFields = new LoginFields();
String numbers = split[2].trim();
String removeBracket = numbers.substring(1, numbers.length() - 1);
String items[] = removeBracket.split(";");
StringBuilder panelNumbers = new StringBuilder();
for( int i=0; i < items.length; i++){
String r = items[i].replaceAll("[item=]","").trim();
panelNumbers.append( r );
}
loginFields.ckeckAuth = (Integer.valueOf(split[0]) == 1 ) ? true : false;
loginFields.balance = Integer.valueOf( split[1].trim() );
loginFields.panelNumbers = panelNumbers;
return loginFields;
}
public List<ReceiveFields> getReceivedSMS(long idToDown, long count) throws TException {
SoapObject request = new SoapObject(Strings.URL_TSMS , Strings.NAME_METHOD_GET_RECEIVE_MESSAGE);
request.addProperty("userName", this.user.userName);
request.addProperty("passWord", this.user.passWord);
request.addProperty("idToDown", idToDown);
request.addProperty("count_request", count);
String str = WSDLHelper.call(request);
String[] strings = WSDLHelper.convert2(WSDLHelper.convert1(str));
List<ReceiveFields> receiveArray = new ArrayList<ReceiveFields>();
DatabaseHandler db = new DatabaseHandler(context);
if (strings != null) {
for (int i = 0; i <= strings.length - 1; i++) {
String[] str1 = WSDLHelper.convert3(strings[i]);
try {
receiveArray.add(new ReceiveFields(
Long.valueOf(str1[0]),
str1[1],
str1[2],
URLDecoder.decode(str1[3], "UTF-8"),
URLDecoder.decode(str1[4], "UTF-8"),
WSDLHelper.convertDate(str1[5])));
db.addToReceived(new ReceiveFields(
Long.valueOf(str1[0]),
str1[1],
str1[2],
URLDecoder.decode(str1[3], "UTF-8"),
URLDecoder.decode(str1[4], "UTF-8"),
WSDLHelper.convertDate(str1[5])));
}
catch (UnsupportedEncodingException ex) {
throw new TException(PublicErrorList.NOT_EXIST_ERROR_DETAIL);
}
}
}
return receiveArray;
}
public String sendSms( SendSms sms ) throws TException {
SoapObject request = new SoapObject(Strings.URL_TSMS , Strings.NAME_METHOD_SEND_MESSAGE);
request.addProperty("user", this.user.userName);
request.addProperty("pass", this.user.passWord);
request.addProperty("sms_number", sms.senderNumber);
request.addProperty("mobile", sms.receiverNumber);
request.addProperty("msg", sms.text);
request.addProperty("send_date", WSDLHelper.convertDate( sms.dateTime) );
return WSDLHelper.call(request);
}
}
User上课：
public class User {
public String userName;
public String passWord;
public User(String userName, String passWord) {
this.userName = userName;
this.passWord = passWord;
}
}
答案 0 :(得分：2)
更改TSMS类构造函数
public TSMS(Context context , User user) {
this.user = user;
this.context = context;
}
答案 1 :(得分：1)
据我所知，我认为你仍然不确定Context in android。 解决根问题的一些建议： 1）在 在这里，你可以使用PG_Android的解决方案来解决错误，但如果你不能从你的活动中传递主要背景，你仍然无法解决根本问题。 只需检查您调用/初始化主类的主要活动（我认为是TSMS）
并通过适当的上下文修复主要问题，如： 这里你的ReceiveFields()构造函数中，您只需使用上下文变量来解决错误，如下所示。Context ctx = null;
public ReceiveFields(Context ctx){
this.ctx=ctx; //create a field Context ctx;
}
TSMS obj = new TSMS(your_current_activity.this);
your_current_activity.this将作为所有类和数据库中的主要上下文..我想你理解..