将记录添加到数据库中，程序中出现错误
日志
04-02 09:22:08.601: W/dalvikvm(4332): threadid=1: thread exiting with uncaught exception (group=0x40018578)
04-02 09:22:10.023: E/AndroidRuntime(4332): FATAL EXCEPTION: main
04-02 09:22:10.023: E/AndroidRuntime(4332): java.lang.NullPointerException
04-02 09:22:10.023: E/AndroidRuntime(4332): at com.example.ok1.MySqlCursorAdapter.onClick(MySqlCursorAdapter.java:87)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.view.View.performClick(View.java:2485)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.widget.CompoundButton.performClick(CompoundButton.java:99)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.view.View$PerformClick.run(View.java:9080)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.os.Handler.handleCallback(Handler.java:587)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.os.Handler.dispatchMessage(Handler.java:92)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.os.Looper.loop(Looper.java:130)
04-02 09:22:10.023: E/AndroidRuntime(4332): at android.app.ActivityThread.main(ActivityThread.java:3687)
04-02 09:22:10.023: E/AndroidRuntime(4332): at java.lang.reflect.Method.invokeNative(Native Method)
04-02 09:22:10.023: E/AndroidRuntime(4332): at java.lang.reflect.Method.invoke(Method.java:507)
04-02 09:22:10.023: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
04-02 09:22:10.023: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
04-02 09:22:10.023: E/AndroidRuntime(4332): at dalvik.system.NativeStart.main(Native Method)
MySqlCursorAdapter
package com.example.ok1;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
public class MySqlCursorAdapter extends SimpleCursorAdapter implements
OnClickListener {
final String Tag = "States";
private Context context;
private DBHelper dbHelper;
private Cursor currentCursor;
public MySqlCursorAdapter(Context context, int layout, Cursor c,
String[] from, int[] to, DBHelper dbHelper) {
super(context, layout, c, from, to);
Log.d(Tag, "трассировка1");
this.currentCursor = c;
this.context = context;
this.dbHelper = dbHelper;
Log.d(Tag, "MySqlCursorAdapter()");
Integer b = c.getCount();
Log.d(Tag, "b=" + b);
}
public View getView(int pos, View inView, ViewGroup parent) {
Log.d(Tag, "getView() + posss=" + pos);
View v = inView;
if (v == null) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.my_list_item, null);
}
this.currentCursor.moveToPosition(pos);
CheckBox cBox = (CheckBox) v.findViewById(R.id.bcheck);
cBox.setTag(Integer.parseInt(this.currentCursor
.getString(this.currentCursor
.getColumnIndex(DBHelper.COLUMN_ID))));
Log.d(Tag, "tag=" + cBox.getTag().toString());
if (this.currentCursor.getString(this.currentCursor
.getColumnIndex(DBHelper.COLUMN_STATUS)) != null
&& Integer.parseInt(this.currentCursor
.getString(this.currentCursor
.getColumnIndex(DBHelper.COLUMN_STATUS))) != 0) {
cBox.setChecked(true);
} else {
cBox.setChecked(false);
}
cBox.setOnClickListener(this);
TextView txtTitle = (TextView) v.findViewById(R.id.txtTitle);
txtTitle.setText(this.currentCursor.getString(this.currentCursor
.getColumnIndex(DBHelper.COLUMN_NAME)));
return (v);
}
public void ClearSelections() {
Log.d(Tag, "ClearSelections()");
this.dbHelper.clearSelections();
this.currentCursor.requery();
}
@Override
public void onClick(View v) {
Log.d(Tag, "onClick");
CheckBox cBox = (CheckBox) v;
Integer _id = (Integer) cBox.getTag();
Log.d(Tag, "Integer _id=" + _id.toString());
ContentValues values = new ContentValues();
values.put(" status", cBox.isChecked() ? 1 : 0);
try {
this.dbHelper.dbSqlite.update("mytable", values, "_id = ?",
new String[] { Integer.toString(_id) });
} catch (SQLException sqle) {
Log.d(Tag, "неудача");
throw sqle;
}
}
}
错误出现在
行中"this.dbHelper.dbSqlite.update("mytable", values, "_id = ?", new String[] { Integer.toString(_id) });"`
答案 0 :(得分：1)
请检查您是否在DBHelper类中对象，因为dbsqlite已初始化
dbHelper.dbSqlite
正如您在问题中通过引用此行已经提到的那样。可能是你的dbSqlite没有初始化
if(dbHelper.dbSqlite==null)
// init first then used
答案 1 :(得分：1)
dbSqlite课程中的 DBhelper从未initialized。请这样做以避免NPE
将此方法添加到您的DBhelper类
private void open() throws SQLException {
dbSqlite = this.getWritableDatabase();
}
并在构造函数中调用它
public DBHelper(Context context) {
super(context, "myDB", null, 1);
open();
}
但它上面说的不是处理数据库的最佳方式，但它可以帮助你继续前进
最好的方法是在您的DBHelper类中添加一个open（）和close（）方法，以便您可以在正确的条件下管理连接
关闭方法
public void close() {
this.close();
}
open（）方法
public void open() throws SQLException {
dbSqlite = this.getWritableDatabase();
}
onclick（）
中的MySqlCursorAdapter类 try {
DBhelper helper = new DBhelper(this);
helper.open();
helper.update("mytable", values, "_id = ?",
new String[] { Integer.toString(_id) });
helper.close();
} catch (SQLException sqle) {
Log.d(Tag, "неудача");
throw sqle;
}
}
答案 2 :(得分：0)
DBHelper
包com.example.ok1;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.util.Log;
public class DBHelper extends SQLiteOpenHelper {
final String Tag="States";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_DATA = "data_id";
public static final String COLUMN_NAME = "name";
public static final String COLUMN_STATUS = "status";
public static final String TABLE_NAME = "mytable";
public SQLiteDatabase dbSqlite;
public DBHelper(Context context) {
// конструктор суперкласса
super(context, "myDB", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(Tag, "--- onCreate database ---");
// создаем таблицу с полями
db.execSQL("create table mytable ("
+ "_id integer primary key autoincrement,"
+ "data_id text,"
+ "name text,"
+ "task text,"
+ "status integer"
+ ");");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void clearSelections() {
Log.d(Tag, "clearSelections()");
ContentValues values = new ContentValues();
values.put(" selected", 0);
this.dbSqlite.update(DBHelper.TABLE_NAME, values, null, null);
}
public Cursor getCursor() {
Log.d(Tag, "getCursor() получили курсор с базы");
String[] columns = null;
String selection = null;
String[] selectionArgs = null;
String groupBy = null;
String having = null;
String orderBy = null;
// SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
// queryBuilder.setTables(TABLE_NAME);
// String[] asColumnsToReturn = new String[] { COLUMN_ID, COLUMN_NAME,
// COLUMN_DATA, COLUMN_STATUS };
// Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn, null,
// null, null, null, "title ASC");
// Log.d(Tag, "getCursor() получили курсор с базы конец");
final SQLiteDatabase db = this.getWritableDatabase();
columns = new String[] { COLUMN_ID, COLUMN_NAME, COLUMN_STATUS };
// selection = "data_id = ?";
// selectionArgs = new String[] {id_for_listtsk_today};
Cursor c = db.query("mytable", columns, null, null, null, null, null);
return c;
}
}
答案 3 :(得分：0)
您是否检查过表格是否已创建
db.execSQL（“create table mytable（” +“_id整数主键自动增量” +“data_id text” +“名称文字” +“任务文字” +“状态整数” +“）;”）;
你没有在表创建中添加空格..使用此