android.database.CursorIndexOutOfBoundsException:请求索引10,大小为10
我正在学习使用SQLite操作的android。以下代码导致出现android.database.CursorIndexOutOfBoundsException:请求索引10,大小为10,android,sqlite,offset,indexoutofboundsexception,Android,Sqlite,Offset,Indexoutofboundsexception,我正在学习使用SQLite操作的android。以下代码导致出现游标IndexOutofBoundsException,但我不知道原因: for (int i = 0; i < cursor.getCount(); i++) { cursor.move(i); String username = cursor.getString(1); Log.i("username", username); } 您可以看到行计数为10,但在获取第5行时会抛出异常 完整代码为:
游标IndexOutofBoundsException
,但我不知道原因:
for (int i = 0; i < cursor.getCount(); i++) {
cursor.move(i);
String username = cursor.getString(1);
Log.i("username", username);
}
您可以看到行计数为10,但在获取第5行时会抛出异常
完整代码为:
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
public class MyActivity extends Activity {
private SQLiteDatabase db;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
createTables();
insertData();
queryData();
}
private void queryData() {
Cursor cursor = db.query("users", new String[]{"_id", "username", "password"}, null, null, null, null, null, null);
if (cursor.moveToFirst()) {
Log.i("row count: ", "" + cursor.getCount());
for (int i = 0; i < cursor.getCount(); i++) {
cursor.move(i);
String username = cursor.getString(1);
Log.i("username", username);
}
}
}
private void insertData() {
for (int i = 0; i < 10; i++) {
String sql = "insert into users(username, password) values('aaa_" + i + "','123_" + i + "')";
db.execSQL(sql);
}
}
private void createTables() {
this.deleteDatabase("temp.db");
db = this.openOrCreateDatabase("temp.db", MODE_PRIVATE, null);
String sql = "create table users(_id integer primary key autoincrement, username text, password text)";
db.execSQL(sql);
}
}
导入android.app.Activity;
导入android.database.Cursor;
导入android.database.sqlite.SQLiteDatabase;
导入android.os.Bundle;
导入android.util.Log;
公共类MyActivity扩展了活动{
专用数据库数据库;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
createTables();
insertData();
queryData();
}
私有void queryData(){
Cursor Cursor=db.query(“用户”,新字符串[]{“\u id”,“用户名”,“密码”},null,null,null,null,null);
if(cursor.moveToFirst()){
Log.i(“行计数:”,“+cursor.getCount());
对于(int i=0;i
这是因为移动(整数偏移)
执行以下操作:
将光标从当前位置向前或向后移动相对量
您不应该使用api。这是将位置移动一个偏移量。改用
Cursor.moveToPosition
试试这个
cursor.moveToFirst();
for (int i = 0; i < cursor.getCount(); i++)
{
String username = cursor.getString(1);
Log.i("username", username);
cursor.moveToNext()
}
cursor.moveToFirst();
对于(int i=0;i
或者根据你的代码
private void queryData() {
Cursor cursor = db.query("users", new String[]{"_id", "username", "password"}, null, null, null, null, null, null);
if (cursor.moveToFirst()) {
Log.i("row count: ", "" + cursor.getCount());
for (int i = 0; i < cursor.getCount(); i++) {
String username = cursor.getString(1);
Log.i("username", username);
cursor.moveToNext()
}
}
}
private void queryData(){
Cursor Cursor=db.query(“用户”,新字符串[]{“\u id”,“用户名”,“密码”},null,null,null,null,null);
if(cursor.moveToFirst()){
Log.i(“行计数:”,“+cursor.getCount());
对于(inti=0;i
使用do while循环而不是for循环
if (cursor.getCount() != 0)
{
if (cursor.moveToFirst())
{
do
{
// cursor.getString(cursor.getColumnIndex("username")));
} while (cursor.moveToNext());
}
}
无需执行cursor.moveToFirst();只需用cursor.moveToNext()将整个内容包装起来;
if (cursor.getCount() != 0)
{
if (cursor.moveToFirst())
{
do
{
// cursor.getString(cursor.getColumnIndex("username")));
} while (cursor.moveToNext());
}
}