我正在開發 android 項目并獲取空對象引用數據庫助手類package com.example.smartpmr;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class DataBaseHelper extends SQLiteOpenHelper { // DATABASE NAME private static final String DATABASE_NAME = "PMR"; // DATABASE VERSION private static final int DATABASE_VERSION = 1; // PATIENT TABLE private static final String TABLE_PATIENT = "tblPatient"; // DOCTOR TABLE private static final String TABLE_DOCTOR = "tblDoctor"; // PRESCRIPTION TABLE private static final String TABLE_PRESCRIPTION = "tblPrescription"; // MEDICINE TABLE private static final String TABLE_MEDICINES = "tblMedicines"; // PATIENT TABLE COLUMNS public static final String PATIENT_ID = "PATIENT_ID"; public static final String PATIENT_NAME = "PATIENT_NAME"; public static final String PATIENT_EMAIL = "PATIENT_EMAIL"; public static final String PATIENT_PASSWORD = "PATIENT_PASSWORD"; public static final String PATIENT_AGE = "PATIENT_AGE"; public static final String PATIENT_CONTACT = "PATIENT_CONTACT"; public static final String PATIENT_ADDRESS = "PATIENT_ADDRESS"; // DOCTOR TABLE COLUMS public static final String DOCTOR_ID = "DOCTOR_ID"; public static final String DOCTOR_NAME = "DOCTOR_NAME"; public static final String DOCTOR_EMAIL = "DOCTOR_EMAIL"; public static final String DOCTOR_PASSWORD = "DOCTOR_PASSWORD"; public static final String DOCTOR_CONTACT = "DOCTOR_CONTACT";
1 回答
一只甜甜圈
TA貢獻1836條經驗 獲得超5個贊
您沒有db在方法中初始化insertPrescription()并且saveMedicine()（就像您在其他方法中正確執行的那樣）：
db = this.getWritableDatabase();
所以db當你使用它時它是空的。
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