无法在android中从SQL数据库中的列检索数据
我一直在开发一个有SQL数据库的应用程序。当按下按钮时,我试图检索SQL数据库“YEAR_DETAILS”的特定列“COL3”中的数据,但我遇到了很多错误。有人能告诉我我做错了什么吗无法在android中从SQL数据库中的列检索数据,android,sql,Android,Sql,我一直在开发一个有SQL数据库的应用程序。当按下按钮时,我试图检索SQL数据库“YEAR_DETAILS”的特定列“COL3”中的数据,但我遇到了很多错误。有人能告诉我我做错了什么吗 public class AddTransaction extends AppCompatActivity { int type1 ; int type2; double amount; ArrayList<add_transaction_data> data;
public class AddTransaction extends AppCompatActivity {
int type1 ;
int type2;
double amount;
ArrayList<add_transaction_data> data;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_transaction);
ActionBar actionBar = getSupportActionBar();
assert actionBar != null;
actionBar.hide();
populateList();
final ImageButton cancel = findViewById(R.id.at_btn_cancel);
final EditText EditAmount = findViewById(R.id.at_enter_amount);
ImageButton save = findViewById(R.id.at_btn_save);
ImageButton income = findViewById(R.id.at_btn_income);
ImageButton loan = findViewById(R.id.at_btn_loan);
RecyclerView recyclerView = findViewById(R.id.at_btn_recyclerview);
recyclerView.setLayoutManager(new GridLayoutManager(this , 5));
recyclerView.setAdapter(new at_btn_adapter(data, new onClickRecyclerButtion() {
@Override
public void onPositionClicked(int position) {
type1 = 2;
type2 = position;
}
}));
income.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
type1 = 1;
type2 = -1;
}
});
loan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
type1 = 1;
type2 = -2;
}
});
context = this;
save.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
System.out.println("it is all cool here");
DatabaseHelper1 databaseHelper1 = new DatabaseHelper1(getBaseContext());
DatabaseHelper2 databaseHelper2 = new DatabaseHelper2(getBaseContext());
double amount = Double.parseDouble(EditAmount.getText().toString());
System.out.println(amount);
Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
String m = changeString(month);
System.out.println(type1);
double mRamount = -1;
if(type1 == 1){
Cursor cursor = databaseHelper1.getRemainingAmount(m , String.valueOf(year));
mRamount= cursor.getDouble(3);
System.out.println(mRamount);//printing amount.
}
startActivity(new Intent(AddTransaction.this , MainActivity.class));
}
});
cancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(AddTransaction.this , MainActivity.class));
}
});
}
void populateList(){
data = new ArrayList<>();
data.add(new add_transaction_data("Add" , R.drawable.ic_add_black_24dp));
data.add(new add_transaction_data("Shopping" , R.drawable.at_ic_shopping));
data.add(new add_transaction_data("Food" , R.drawable.at_ic_food));
data.add(new add_transaction_data("Traveling" , R.drawable.at_ic_travel));
data.add(new add_transaction_data("Education" , R.drawable.at_ic_education));
data.add(new add_transaction_data("Energy" , R.drawable.at_ic_energy));
data.add(new add_transaction_data("House" , R.drawable.at_ic_home));
data.add(new add_transaction_data("Fitness" , R.drawable.at_ic_sports));
data.add(new add_transaction_data("Personal" , R.drawable.at_ic_personal));
data.add(new add_transaction_data("Other" , R.drawable.at_ic_other));
}
String changeString(int month){
String m;
switch (month){
case 0:
m = "January";
break;
case 1:
m = "Feburary";
break;
case 2:
m = "March";
break;
case 3:
m = "April";
break;
case 4:
m = "May";
break;
case 5:
m = "June";
break;
case 6:
m = "July";
break;
case 7:
m = "August";
break;
case 8:
m = "September";
break;
case 9:
m = "October";
break;
case 10:
m = "November";
break;
case 11:
m = "December";
break;
default:
m = " ";
}
return m;
}
}
公共类AddTransaction扩展了AppCompative活动{
int类型1;
int类型2;
双倍金额;
阵列列表数据;
语境;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u add\u事务);
ActionBar ActionBar=getSupportActionBar();
断言actionBar!=null;
actionBar.hide();
大众主义者();
最终图像按钮取消=findViewById(R.id.at_btn_cancel);
最终编辑文本编辑金额=findViewById(R.id.at\u输入金额);
ImageButton save=findViewById(R.id.at_btn_save);
ImageButton收入=findViewById(R.id.at_btn_收入);
ImageButton loan=findViewById(R.id.at_btn_loan);
RecyclerView RecyclerView=findViewById(R.id.at_btn_RecyclerView);
setLayoutManager(新的GridLayoutManager(this,5));
setAdapter(新的at_btn_适配器(数据,新的onClickRecyclerButton()){
@凌驾
单击位置时的公共无效(内部位置){
类型1=2;
类型2=位置;
}
}));
income.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
类型1=1;
类型2=-1;
}
});
loan.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
类型1=1;
类型2=-2;
}
});
上下文=这个;
save.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
System.out.println(“这里很酷”);
DatabaseHelper1 DatabaseHelper1=新的DatabaseHelper1(getBaseContext());
DatabaseHelper2 DatabaseHelper2=新的DatabaseHelper2(getBaseContext());
double amount=double.parseDouble(EditAmount.getText().toString());
系统输出打印项次(金额);
Calendar c=Calendar.getInstance();
int year=c.get(日历年);
int month=c.get(日历月);
字符串m=变更字符串(月);
系统输出打印项次(类型1);
双mRamount=-1;
如果(类型1==1){
Cursor Cursor=databaseHelper1.getRemainingAmount(m,String.valueOf(year));
mRamount=cursor.getDouble(3);
System.out.println(mRamount);//打印量。
}
startActivity(新意图(AddTransaction.this,MainActivity.class));
}
});
cancel.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
startActivity(新意图(AddTransaction.this,MainActivity.class));
}
});
}
void populateList(){
数据=新的ArrayList();
data.add(新的add_事务_数据(“add”,R.drawable.ic_add_black_24dp));
data.add(新的add_事务_数据(“Shopping”,R.drawable.at_ic_Shopping));
data.add(新的add_事务_数据(“Food”,R.drawable.at_ic_Food));
data.add(新的add_事务_数据(“旅行”,R.drawable.at_ic_旅行));
data.add(新的add_事务_数据(“教育”,R.drawable.at_ic_教育));
data.add(新的add_事务_数据(“Energy”,R.drawable.at_ic_Energy));
data.add(新的add_事务_数据(“House”,R.drawable.at_ic_home));
data.add(新的add_事务_数据(“Fitness”,R.drawable.at_ic_sports));
数据添加(新添加交易数据(“个人”,R.drawable.at_ic_Personal));
data.add(新的add_事务_数据(“其他”,R.drawable.at_ic_其他));
}
字符串更改字符串(整数月){
字符串m;
开关(月){
案例0:
m=“一月”;
打破
案例1:
m=“二月”;
打破
案例2:
m=“三月”;
打破
案例3:
m=“四月”;
打破
案例4:
m=“可能”;
打破
案例5:
m=“六月”;
打破
案例6:
m=“7月”;
打破
案例7:
m=“八月”;
打破
案例8:
m=“9月”;
打破
案例9:
m=“10月”;
打破
案例10:
m=“11月”;
打破
案例11:
m=“12月”;
打破
违约:
m=“”;
}
返回m;
}
}
数据库帮助程序:
public class DatabaseHelper1 extends SQLiteOpenHelper {
private static final int version = 3;
private static final String name = "YEAR_DETAILS";
private static final String COL0 = "YEAR";
private static final String COL1 = "MONTH";
private static final String COL2 = "SPENT";
private static final String COL3 = "REMAINING";
private static final String TAG = "Database Helper 1";
public DatabaseHelper1(@Nullable Context context) {
super(context, name, null, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG , "Database 1 is being created");
String create_table = "CREATE TABLE "+name+"("+
COL0+" INTEGER, "+
COL1+" TEXT, "+
COL2+" DOUBLE, "+
COL3+" DOUBLE);";
db.execSQL(create_table);
}
@Override
public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+name);
onCreate(db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
private boolean createMonth(String month , String year){
Log.d(TAG , "month row is being created");
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL0 , year);
contentValues.put(COL1 , month);
contentValues.put(COL2 , 0.0);
contentValues.put(COL3 , 0.0);
long result = db.insert(name,null , contentValues);
return result != -1;
}
public boolean spentChange(String month , String year , Double newAmount){
Log.d(TAG , "spent amount is being changed");
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COL2 , newAmount);
long result = db.update(name, values , "MONTH = ? AND YEAR = ?", new String[]{month , year});
return result != -1;
}
public boolean remainingChange(String month ,String year, Double newAmount){
Log.d(TAG , "Remaining amount is being changed");
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues =new ContentValues();
contentValues.put(COL3 , newAmount);
long result = db.update(name , contentValues , "MONTH = ? AND YEAR = ?" , new String[]{month , year});
return result != -1;
}
public void checkExistance(String month, String year){
Log.d(TAG , "Checking if month already exits");
SQLiteDatabase database = this.getWritableDatabase();
Cursor cur = database.query(name , null , "MONTH = ? AND YEAR = ?" , new String[]{month , year} , null , null , null);
System.out.println(cur);
if(cur.getCount() <= 0) {
boolean b = createMonth(month , year);
if(b)
Log.d(TAG , "checkExistance: failed to create month");
else
Log.d(TAG, "checkExistance: month created successfully");
}
}
public Cursor getdata(){
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT * FROM YEAR_DETAILS;";
return db.rawQuery(query , null);
}
public Cursor getSpentAmount(String month , String year){
SQLiteDatabase db = this.getReadableDatabase();
String query = "SELECT * FROM YEAR_DETAILS WHERE MONTH = " + month+ " AND YEAR = "+year;
return db.rawQuery(query , null);
}
public Cursor getRemainingAmount(String month , String year){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cur = db.query(name , new String[]{COL3} , "MONTH = ? AND YEAR = ?" , new String[]{month , year} , null , null , null);
return cur;
}
}
公共类DatabaseHelper1扩展了SQLiteOpenHelper{
私有静态最终int版本=3;
私有静态最终字符串name=“年份详情”;
私有静态最终字符串COL0=“年”;
私有静态最终字符串COL1=“月”;
私有静态最终字符串COL2=“已用”;
私有静态最终字符串COL3=“剩余”;
私有静态最终字符串TAG=“Database Helper 1”;
公共数据库Helper1(@Nullable Context){
super(上下文、名称、null、版本);
}
@凌驾
public void onCreate(SQLiteDatabase db){
Log.d(标记“正在创建数据库1”);
字符串create_table=“create table”+name+”(“+
private SQLiteDatabase db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_transaction);
db = new MyHelper(this).getWritableDatabase();
ActionBar actionBar = getSupportActionBar();
assert actionBar != null;
actionBar.hide();
populateList();
String query = "SELECT * FROM YEAR_DETAILS;";
String query = "SELECT * FROM YEAR_DETAILS";