我正在尝试在SQLite Eclipse上执行此数据库教程：https://www.youtube.com/watch?v=j-IV87qQ00M
但最后我收到了一些错误..
在db.ppen（）;我得到错误：方法open（）未定义类型MainActivity.DBAdapter 插入记录和关闭类似。
MainActivity：
package com.example.studentdatabase;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
//DBAdapter db = new DBAdapter(this);
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button addBtn = (Button)findViewById(R.id.add);
addBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivity.this, addassignment.class);
startActivity(i);
}
});
try {
String destPath = "/data/data/" + getPackageName() + "/databases/AssignmentDB";
File f = new File(destPath);
if (!f.exists()) {
CopyDB( getBaseContext().getAssets().open("mydb"),
new FileOutputStream(destPath));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
DBAdapter db = new DBAdapter();
//---add an assignment---
db.open();
long id = db.insertRecord("Hello World", "2/18/2012", "DPR 224", "First Android Project");
id = db.insertRecord("Workbook Exercises", "3/1/2012", "MAT 100", "Do odd numbers");
db.close();
//---get all Records---
/*
db.open();
Cursor c = db.getAllRecords();
if (c.moveToFirst())
{
do {
DisplayRecord(c);
} while (c.moveToNext());
}
db.close();
*/
/*
//---get a Record---
db.open();
Cursor c = db.getRecord(2);
if (c.moveToFirst())
DisplayRecord(c);
else
Toast.makeText(this, "No Assignments found", Toast.LENGTH_LONG).show();
db.close();
*/
//---update Record---
/*
db.open();
if (db.updateRecord(1, "Hello Android", "2/19/2012", "DPR 224", "First Android Project"))
Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG).show();
else
Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show();
db.close();
*/
/*
//---delete a Record---
db.open();
if (db.deleteRecord(1))
Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG).show();
else
Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show();
db.close();
*/
}
private class DBAdapter extends BaseAdapter {
private LayoutInflater mInflater;
//private ArrayList<>
@Override
public int getCount() {
return 0;
}
@Override
public Object getItem(int arg0) {
return null;
}
@Override
public long getItemId(int arg0) {
return 0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
return null;
}
}
public void CopyDB(InputStream inputStream, OutputStream outputStream)
throws IOException {
//---copy 1K bytes at a time---
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, length);
}
inputStream.close();
outputStream.close();
}
public void DisplayRecord(Cursor c)
{
Toast.makeText(this,
"id: " + c.getString(0) + "\n" +
"Title: " + c.getString(1) + "\n" +
"Due Date: " + c.getString(2),
Toast.LENGTH_SHORT).show();
}
public void addAssignment(View view)
{
Intent i = new Intent("com.pinchtapzoom.addassignment");
startActivity(i);
Log.d("TAG", "Clicked");
}
}
DBAdapter代码：
package com.example.studentdatabase;
public class DBAdapter {
public static final String KEY_ROWID = "id";
public static final String KEY_TITLE = "title";
public static final String KEY_DUEDATE = "duedate";
public static final String KEY_COURSE = "course";
public static final String KEY_NOTES = "notes";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "AssignmentsDB";
private static final String DATABASE_TABLE = "assignments";
private static final int DATABASE_VERSION = 2;
private static final String DATABASE_CREATE =
"create table if not exists assignments (id integer primary key autoincrement, "
+ "title VARCHAR not null, duedate date, course VARCHAR, notes VARCHAR );";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
try {
db.execSQL(DATABASE_CREATE);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS contacts");
onCreate(db);
}
}
//---opens the database---
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---insert a record into the database---
public long insertRecord(String title, String duedate, String course, String notes)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_DUEDATE, duedate);
initialValues.put(KEY_COURSE, course);
initialValues.put(KEY_NOTES, notes);
return db.insert(DATABASE_TABLE, null, initialValues);
}
//---deletes a particular record---
public boolean deleteContact(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
//---retrieves all the records---
public Cursor getAllRecords()
{
return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE,
KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, null, null, null, null, null);
}
//---retrieves a particular record---
public Cursor getRecord(long rowId) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES},
KEY_ROWID + "=" + rowId, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
//---updates a record---
public boolean updateRecord(long rowId, String title, String duedate, String course, String notes)
{
ContentValues args = new ContentValues();
args.put(KEY_TITLE, title);
args.put(KEY_DUEDATE, duedate);
args.put(KEY_COURSE, course);
args.put(KEY_NOTES, notes);
return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
addassignment code：
package com.example.studentdatabase;
public class addassignment extends Activity {
DBAdapter db = new DBAdapter(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add);
}
public void addAssignment(View v)
{
Log.d("test", "adding");
//get data from form
EditText nameTxt = (EditText)findViewById(R.id.editTitle);
EditText dateTxt = (EditText)findViewById(R.id.editDuedate);
EditText courseTxt = (EditText)findViewById(R.id.editCourse);
EditText notesTxt = (EditText)findViewById(R.id.editNotes);
db.open();
long id = db.insertRecord(nameTxt.getText().toString(), dateTxt.getText().toString(), courseTxt.getText().toString(), notesTxt.getText().toString());
db.close();
nameTxt.setText("");
dateTxt.setText("");
courseTxt.setText("");
notesTxt.setText("");
Toast.makeText(addassignment.this,"Assignment Added", Toast.LENGTH_LONG).show();
}
public void viewAssignments(View v)
{
Intent i = new Intent(this, MainActivity.class);
startActivity(i);
}
}
这里有什么问题？提前谢谢。
答案 0 :(得分：0)
您有两个名为DBAdapter的班级。另一个是MainActivity中的内部类，另一个是单独的类。 open()在单独的类中定义，而MainActivity隐式使用内部类版本。
要修复它，要么使用完全限定的包名称来引用该类，要么只重命名另一个类以将它们分开。