代码如下
...
public class broad extends BroadcastReceiver{
...
// 数据库变量
DatabaseHelper mDBH;
public static final String DATABASE_NAME = "power.db";
public static final int DATABASE_VERSION = 1;
public static final String TABLE_NAME = "power";
public static final String DATE = "date";
public static final String TIME = "time";
public static final String POWER = "power";
public static final String STATUS = "status";
public static String strSql;
// 数据库类
private static class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
Log.i("Orange:DatabaseHelper=", "OK");
}
// 没有数据表时，建立数据表
@Override
public void onCreate(SQLiteDatabase db) {
Log.i("Orange:createDB1=", "OK");
strSql = "CREATE TABLE " + TABLE_NAME + " (" + DATE
+ " text not null, " + TIME + " text not null, " + POWER
+ " int not null, " + STATUS + " text not null" + ");";
Log.i("Orange:createDB2=", strSql);
db.execSQL(strSql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public void onReceive(Context context, Intent intent)
{
Log.i("Orange=", "119");
// 读取数据库
rdTbl();
}
private void rdTbl() {
// 获得可写数据库
Log.i("Orange=", "120");
SQLiteDatabase db = mDBH.getWritableDatabase();
Log.i("Orange=", "121");
// 查询数据库
String[] col = new String[]{DATE, POWER, STATUS};
Cursor cur = db.query(TABLE_NAME, col, null, null, null, null, null);
Log.i("Orange=", "122");
...
每次执行到Log.i("Orange=", "120");就出错不执行了，然后提示
09-27 12:19:01.994: E/AndroidRuntime(471): java.lang.RuntimeException: Unable to start receiver com.example.powm.broad: java.lang.NullPointerException
就是空指针错误吧？
而且Log.i("Orange:DatabaseHelper=", "OK");和Log.i("Orange:createDB2=", strSql);根本没有执行，就是说DatabaseHelper类的构造函数和onCreate没有执行。
------解决方案--------------------
DatabaseHelper mDBH;
mDBH只是做了声明，然后就拿来使用，肯定会报空指针了。
SQLiteDatabase db = mDBH.getWritableDatabase();
改成
SQLiteDatabase db = SQLiteOpenHelper.getWritableDatabase();
------解决方案--------------------
学习下！真心没有用过SQLies