所以我正在尝试创建一个应用程序，允许用户将字符串放入 SQLite 数据库并查看另一个活动中的日志。但是当我打开下一个活动时，应用程序会强制关闭并崩溃。这是用户将信息放入数据库的活动中的代码
Button ViewLogs = (Button)findViewById(R.id.button1);
ViewLogs.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
Intent view = new Intent(StartBitching.this, ViewLogs.class);
startActivity(view);
// TODO Auto-generated method stub
}
}
);
Button MostWanted = (Button)findViewById(R.id.button2);
MostWanted.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent most = new Intent(StartBitching.this, MostWanted.class);
startActivity(most);
}
});
Button Add = (Button)findViewById(R.id.button3);
Add.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
EditText txtName = (EditText)findViewById(R.id.editText1);
EditText txtDate = (EditText)findViewById(R.id.editText2);
EditText txtSummary = (EditText)findViewById(R.id.editText3);
DatabaseConnector dc = new DatabaseConnector(null);
try
{
String Name = txtName.getText().toString();
String Date = txtDate.getText().toString();
String Summary = txtSummary.getText().toString();
dc.insertLog(Name, Date, Summary);
txtName.setText("");
txtDate.setText("");
txtSummary.setText("");
}
catch(Exception ex)
{
txtName.setText(ex.getMessage().toString());
}
这是我的数据库连接器活动
public class DatabaseConnector{
private static final String DATABASE_NAME = "Blacklist";
private SQLiteDatabase database; // database object
private DatabaseOpenHelper databaseOpenHelper; // database helper
// public constructor for DatabaseConnector
{
Context context = null;
// create a new DatabaseOpenHelper
databaseOpenHelper =
new DatabaseOpenHelper(context, DATABASE_NAME, null, 1);
} // end DatabaseConnector constructor
public DatabaseConnector(ViewLogs viewLogs) {
// TODO Auto-generated constructor stub
}
// open the database connection
public void open() throws SQLException
{
// create or open a database for reading/writing
database = databaseOpenHelper.getWritableDatabase();
} // end method open
// close the database connection
public void close()
{
if (database != null)
database.close(); // close the database connection
} // end method close
// inserts a new dog in the database
public void insertLog(String Name,
String Date, String Summary)
{
try
{
ContentValues newLog = new ContentValues();
newLog.put("Name", Name);
newLog.put("Date", Date);
newLog.put("Summary", Summary);
open(); // open the database
database.insert("logs", null, newLog);
close(); // close the database
}
catch (Exception e){}
} // end method insertDog
public void updateDog(long id, String Name, String Date, String Summary)
{
ContentValues editContact = new ContentValues();
editContact.put("Name", Name);
editContact.put("Date", Date);
editContact.put("Summary", Summary);
open(); // open the database
database.update("logs", editContact, "_id=" + id, null);
close(); // close the database
} // end method updateContact
// return a Cursor with all contact information in the database
public Cursor getAllLogs()
{
return database.query("logs", new String[] {"_id", "Name", "Date", "Summary"},
null, null, null, null, "Name");
} // end method getAllContacts
// get a Cursor containing all information about the contact specified
// by the given id
public Cursor getOneContact(long id)
{
return database.query(
"contacts", null, "_id=" + id, null, null, null, null);
} // end method getOnContact
// delete the contact specified by the given String name
public void deleteLog(long id)
{
open(); // open the database
database.delete("logs", "_id=" + id, null);
close(); // close the database
} // end method deleteContact
private class DatabaseOpenHelper extends SQLiteOpenHelper
{
// public constructor
public DatabaseOpenHelper(Context context, String name,
CursorFactory factory, int version)
{
super(context, name, factory, version);
} // end DatabaseOpenHelper constructor
// creates the contacts table when the database is created
@Override
public void onCreate(SQLiteDatabase db)
{
// query to create a new table named dog
String createQuery = "CREATE TABLE logs" +
"(_id integer primary key autoincrement," +
"Name TEXT," +
"Date TEXT," +
"Summary TEXT);";
db.execSQL(createQuery); // execute the query
} // end method onCreate
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
} // end method onUpgrade
} // end class DatabaseOpenHelper
}
这是应用程序中的代码，应该允许用户查看数据库中的所有日志
public class ViewLogs extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_logs);
DatabaseConnector dc = new DatabaseConnector(this);
dc.open();
Cursor c = dc.getAllLogs();
String[] logs = new String[0];
if (c !=null)
{
do{
String Name = c.getString(c.getColumnIndex("Name"));
String Date = c.getString(c.getColumnIndex("Date"));
String Summary = c.getString(c.getColumnIndex("Summary"));
TableLayout rl1 =(TableLayout)findViewById(R.id.rel);
for( String log: logs)
{
TextView lbl = (TextView)findViewById(R.id.texter);
lbl.setText(log);
rl1.addView(lbl);
}
}while (c.moveToNext());
}
super.onResume();
}
}
我知道这是很多代码，可能很难阅读，但我是编程新手，如果我能得到任何帮助，我将不胜感激