我的程序有一个活动和一个数据库类。有一个用于从数据库中检索数据的按钮。当我按下按钮时应用程序结束。我认为数据库中的一些错误是querry.pls帮我解决的。给出了logcat。 FirstActivity.java
package example.showevent1;
import java.util.Calendar;
import android.os.Bundle;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v4.app.*;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.AdapterView.OnItemSelectedListener;
public class FirstActivity extends FragmentActivity implements OnItemSelectedListener {
/** Called when the activity is first created. */
classdbOpenHelper eventsData;
classdbOpenHelper eventsData1;
TextView userSelection;
Button okButton;
Button addButton;
Button change_date_but;
TextView date;
TextView show;
EditText edittext;
public static final int Date_dialog_id = 1;
private int mYear;
private int mMonth;
private int mDay;
private static final String[] items={"Yalahanka","Rajai nagar","Sivaji Nagar","Koramangala","RT Nagar", "Banashankari","Yashwanthpura","Hebbal"};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
okButton = (Button)findViewById(R.id.button2);
addButton = (Button)findViewById(R.id.button3);
change_date_but = (Button)findViewById(R.id.button1);
date = (TextView)findViewById(R.id.textView2);//KEY_DATE
userSelection=(TextView)findViewById(R.id.textView1);//KEY_DESC
edittext=(EditText)findViewById(R.id.editText1);//KEY_EVENT
show=(TextView)findViewById(R.id.textView5);
Spinner my_spin=(Spinner)findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
ArrayAdapter aa=new ArrayAdapter(this, android.R.layout.simple_spinner_item,items);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
my_spin.setAdapter(aa);
okButton.setOnClickListener(new clicker());
addButton.setOnClickListener(new getclicker());
eventsData = new classdbOpenHelper(this);
change_date_but.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DatePickerDialog DPD = new DatePickerDialog(
FirstActivity.this, mDateSetListener, mYear, mMonth,mDay);
DPD.show();
}
});
final Calendar c = Calendar.getInstance();
mYear = c.get(Calendar.YEAR);
mMonth = c.get(Calendar.MONTH);
mDay = c.get(Calendar.DAY_OF_MONTH);
updateDisplay();
}
@Override
@Deprecated
protected void onPrepareDialog(int id, Dialog dialog) {
// TODO Auto-generated method stub
super.onPrepareDialog(id, dialog);
((DatePickerDialog) dialog).updateDate(mYear, mMonth, mDay);
}
private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
};
private void updateDisplay() {
// TODO Auto-generated method stub
date.setText(new StringBuilder()
// Month is 0 based so add 1
.append(mMonth + 1).append("-").append(mDay).append("-")
.append(mYear));
}
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int pos, long arg3) {
userSelection.setText(items[pos]);
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
userSelection.setText("");
}
class clicker implements Button.OnClickListener {
public void onClick(View v) {
String datevalue = date.getText().toString();
String Userselectvalue = userSelection.getText().toString();
String Userevent = edittext.getText().toString();
SQLiteDatabase db = eventsData.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(classdbOpenHelper.KEY_DESC, Userselectvalue);
cv.put(classdbOpenHelper.KEY_EVENT, Userevent);
cv.put(classdbOpenHelper.KEY_DATE,datevalue);
db.insert(classdbOpenHelper.DATABASE_TABLE, null, cv);
db.close();
}
public void onDestroy() {
eventsData.close();
}
}
class getclicker implements Button.OnClickListener {
public void onClick(View v) {
String datevalue = date.getText().toString();
String Userselectvalue = userSelection.getText().toString();
String showevent = eventsData.getContact(datevalue,Userselectvalue);
show.setText(showevent);
}
}
}
classdbOpenHelper.java
package example.showevent1;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.TextView;
public class classdbOpenHelper extends SQLiteOpenHelper {
public static final String KEY_ROWID = "id";
public static final String KEY_DESC = "countdesc";
public static final String KEY_EVENT = "countevent";
public static final String KEY_DATE = "countdate";
public static final String DATABASE_NAME= "countdb";
public static final String DATABASE_TABLE = "countable";
public static final int DATABASE_VERSION = 1;
public classdbOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + DATABASE_TABLE + "("
+ KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_DESC + " TEXT, " + KEY_EVENT + " TEXT, " + KEY_DATE + " TEXT " + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXITS " + DATABASE_TABLE);
onCreate(db);
}
public String getContact(String datevalue,String Userselectvalue) {
String selection = classdbOpenHelper.KEY_DESC + " = Userselectvalue"
+" AND " + classdbOpenHelper.KEY_DATE + " datevalue";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(classdbOpenHelper.DATABASE_TABLE,
new String[] {classdbOpenHelper.KEY_EVENT }, selection,
null, null, null, null);
String place = cursor.getString(0 );
return place;
}
}
logcat的
08-05 11:21:13.327: E/AndroidRuntime(827): FATAL EXCEPTION: main
08-05 11:21:13.327: E/AndroidRuntime(827): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 0
08-05 11:21:13.327: E/AndroidRuntime(827): at android.database.AbstractCursor.checkPosition(AbstractCursor.java:424)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50)
08-05 11:21:13.327: E/AndroidRuntime(827): at example.showevent1.classdbOpenHelper.getContact(classdbOpenHelper.java:59)
08-05 11:21:13.327: E/AndroidRuntime(827): at example.showevent1.FirstActivity$getclicker.onClick(FirstActivity.java:163)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.view.View.performClick(View.java:4204)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.view.View$PerformClick.run(View.java:17355)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.os.Handler.handleCallback(Handler.java:725)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.os.Handler.dispatchMessage(Handler.java:92)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.os.Looper.loop(Looper.java:137)
08-05 11:21:13.327: E/AndroidRuntime(827): at android.app.ActivityThread.main(ActivityThread.java:5041)
08-05 11:21:13.327: E/AndroidRuntime(827): at java.lang.reflect.Method.invokeNative(Native Method)
08-05 11:21:13.327: E/AndroidRuntime(827): at java.lang.reflect.Method.invoke(Method.java:511)
08-05 11:21:13.327: E/AndroidRuntime(827): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-05 11:21:13.327: E/AndroidRuntime(827): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-05 11:21:13.327: E/AndroidRuntime(827): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
String place = cursor.getString(0 );
您没有正确访问光标。首先使用if(cursor.moveToFirst())检查游标是否为空，然后使用cursor.moveToFirst()将光标移动到第一行。然后，您可以使用cursor.getString(cursor.getColumnIndex(COLUMN_NAME))检索值并将其分配给您需要的字符串。
Logcat显示，`
08-05 11:21:13.327: E/AndroidRuntime(827): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 0`, meaning that you have a problem with cursor operation.
替换
String place = cursor.getString(0 );`
使用
if(cursor.moveToFirst())
cursor.moveToFirst();
String place = cursor.getString(cursor.getColumIndex(COLUMN_NAME))
将COLUMN_NAME替换为数据库中的column_name