我正在开发一个现有的应用程序，它收集一些数据然后写入数据库。
当我尝试将其写入数据库时，我的应用程序崩溃了。我确定我在帮手或设置中遗漏了一些东西，但我没有经验可以理解它是什么。
我的帮助程序类如下：
public class TableSubandObAssessment {
public static final String TAG = "TableSubandObAssessment";
public static final String KEY_TABLE = "assessments";
private static final String KEY_APPOINTMENT_ID = "appointmentID";
private static final String KEY_TYPE = "type";
private static final String KEY_ASSESSMENT = "assessment";
private static final String KEY_VARIABLE1 = "variable1";
private static final String KEY_VARIABLE2 = "vriable2";
private static final String KEY_VARIABLE3 = "vriable3";
private static final String KEY_VARIABLE4 = "vriable4";
private DatabaseHelper helper;
private final Context context;
public static SQLiteDatabase db;
private static final String CREATE_TABLE =
"CREATE TABLE " + KEY_TABLE
+ " (" + KEY_APPOINTMENT_ID + " INTEGER PRIMARY KEY NOT NULL, "
+ KEY_TYPE + " TEXT NOT NULL, "
+ KEY_ASSESSMENT + " TEXT NOT NULL, "
+ KEY_VARIABLE1 + " TEXT, "
+ KEY_VARIABLE2 + " TEXT NOT NULL, "
+ KEY_VARIABLE3 + " TEXT, "
+ KEY_VARIABLE4 + " INT " + ");";
public static void createTable(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
public static void dropTable(SQLiteDatabase db) {
db.execSQL("DROP TABLE IF EXISTS " + KEY_TABLE);
createTable(db);
}
public TableSubandObAssessment(Context context) {
this.context = context;
}
public TableSubandObAssessment open() throws SQLException {
helper = new DatabaseHelper(context);
db = helper.getWritableDatabase();
return this;
}
public void close() {
helper.close();
}
public static long insertTableSubandObAssessment(int appointmentID, String type, String assessment, String variable1, String variable2, String variable3, String variable4) {
ContentValues values = new ContentValues();
values.put(KEY_APPOINTMENT_ID, appointmentID);
values.put(KEY_TYPE, type);
values.put(KEY_ASSESSMENT, assessment);
values.put(KEY_VARIABLE1, variable1);
values.put(KEY_VARIABLE2, variable2);
values.put(KEY_VARIABLE3, variable3);
values.put(KEY_VARIABLE4, variable4);
return db.insert(KEY_TABLE, null, values);
}
}
现有的帮助程序如下（我在对表中的引用中添加了）：
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "PGAAPPOINTMENTS.db";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase db = null;
public DatabaseHelper(Context c) {
super(c, DATABASE_NAME, null, DATABASE_VERSION);
}
public void openToRead() {
close();
db = this.getReadableDatabase();
}
public void openToWrite() {
close();
db = this.getWritableDatabase();
}
public void close() {
if (db != null) {
super.close();
db = null;
}
}
@Override
public void onCreate(SQLiteDatabase db) {
AppointmentTable.createTable(db);
PlayerTable.createTable(db);
PractitionerTable.createTable(db);
TableRoutine.createTable(db);
TableDiagnostic.createTable(db);
TableAssessment.createTable(db);
TableFollowUp.createTable(db);
TableNote.createTable(db);
TableSubandObAssessment.createTable(db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
TableRoutine.dropTable(db);
AppointmentTable.dropTable(db);
TableDiagnostic.dropTable(db);
TableAssessment.dropTable(db);
TableFollowUp.dropTable(db);
TableNote.dropTable(db);
PlayerTable.dropTable(db);
PractitionerTable.dropTable(db);
TableSubandObAssessment.dropTable(db);
onCreate(db);
}
}
我用来设置数据库的方法是：
public void saveToDb(){
createTable(TableSubandObAssessment.db);
int a=(int)ActivityMain.apID;
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Observation", Active_Movements.obs, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Joint Integrity Test", Active_Movements.JIT, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Active Movements", Active_Movements.amv, Active_Movements.amv2,Active_Movements.amv3,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Passive Movements", Active_Movements.passive, Active_Movements.passive1,Active_Movements.passive2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Repeated Movements", Active_Movements.repm, Active_Movements.repm1,Active_Movements.repm2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Combined Movements", Active_Movements.comb, Active_Movements.comb1,Active_Movements.comb2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Capsular Pattern", Active_Movements.cappat, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Joint Effusion", Active_Movements.joint_eff, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "PPIVMs", Active_Movements.PPIVMS, Active_Movements.PPIVMS2,Active_Movements.PPIVMS3,Active_Movements.PPIVMS4);
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Other Joints Involved", Active_Movements.other_joints, Active_Movements.other_joints1,"","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Muscle Strength", Active_Movements.muscst, Active_Movements.muscst1,Active_Movements.muscst2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Muscle Control",Active_Movements.musccont, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Muscle Length", Active_Movements.musclength, Active_Movements.musclength1,Active_Movements.musclength2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Isometric Muscle Tests",Active_Movements.imt, "", "","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Integrity Of Nervous System", Active_Movements.INS, Active_Movements.INS1,Active_Movements.INS2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Mobility Of Nervous System", Active_Movements.MobNS, Active_Movements.MobNS1,Active_Movements.MobNS2,"");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Diagnostic Tests", Active_Movements.diagt, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Special Tests", Active_Movements.spect, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Accessory Movements", Active_Movements.accm, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Palpation", Active_Movements.palp, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Conclusion", Active_Movements.conc, "","","");
TableSubandObAssessment.insertTableSubandObAssessment(a, "Objective", "Diagnosis", Active_Movements.Diag, Active_Movements.Diag1,Active_Movements.Diag2,"");
}
这里是logcat（我没有想法如何解释）：
07-27 11:37:16.757: E/AndroidRuntime(12807): FATAL EXCEPTION: main
07-27 11:37:16.757: E/AndroidRuntime(12807): java.lang.NullPointerException
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.ucl.pga.db.TableSubandObAssessment.insertTableSubandObAssessment(TableSubandObAssessment.java:73)
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.ucl.pga.db.Objective.Summary.saveToDb(Summary.java:921)
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.ucl.pga.db.Objective.Summary$2$1.onClick(Summary.java:495)
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
07-27 11:37:16.757: E/AndroidRuntime(12807): at android.os.Handler.dispatchMessage(Handler.java:99)
07-27 11:37:16.757: E/AndroidRuntime(12807): at android.os.Looper.loop(Looper.java:137)
07-27 11:37:16.757: E/AndroidRuntime(12807): at android.app.ActivityThread.main(ActivityThread.java:4745)
07-27 11:37:16.757: E/AndroidRuntime(12807): at java.lang.reflect.Method.invokeNative(Native Method)
07-27 11:37:16.757: E/AndroidRuntime(12807): at java.lang.reflect.Method.invoke(Method.java:511)
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-27 11:37:16.757: E/AndroidRuntime(12807): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-27 11:37:16.757: E/AndroidRuntime(12807): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
我认为您要写入的属性db是null。您应该在TableSubandObAssessment.open()之前致电insertTableSubandObAssessment()，因为这会初始化您的属性。请注意，createTable的参数是shadowing您的属性，不为插入方法初始化它。