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在Android应用程序中，我想通过三个EditText视图从用户那里获取输入，然后按ta按钮我想将它们保存到我的数据库中，但是当我按下按钮时，一个意外错误使我的应用程序关闭。应该如何我管这个？

这是我的按钮：

//---btnInsert
        Button btnInsert=(Button)findViewById(R.id.btnInsert);

        btnInsert.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                DBAdapter    db = new DBAdapter(DatabaseAndroid10.this); 
                 long id;
                 String ISBN;
                 String Title;
                 String Publisher;

                 EditText txtISBN=(EditText)findViewById(R.id.txtISBN);
                 EditText txtTitle=(EditText)findViewById(R.id.txtTitle);
                 EditText txtPublisher=(EditText)findViewById(R.id.txtPublisher);

                  ISBN = txtISBN.getText().toString();
                  Title=txtTitle.getText().toString();
                  Publisher=txtPublisher.getText().toString();

                  id = db.insertTitle(
                            ISBN,Title,Publisher);    

                    db.close();
            }   
        });

这是我的 DBAdapter：

package com.example.databaseandroid10;

import android.content.ContentValues;

public class DBAdapter 
{
    public static final String KEY_ROWID = "_id";
    public static final String KEY_ISBN = "isbn";
    public static final String KEY_TITLE = "title";
    public static final String KEY_PUBLISHER = "publisher";    
    private static final String TAG = "DBAdapter";

    private static final String DATABASE_NAME = "books";
    private static final String DATABASE_TABLE = "titles";
    private static final int DATABASE_VERSION = 1;

    private static final String DATABASE_CREATE =
        "create table titles (_id integer primary key autoincrement, "
        + "isbn text not null, title text not null, " 
        + "publisher text not null);";

    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) 
        {
            db.execSQL(DATABASE_CREATE);
        }

        @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 titles");
            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 title into the database---
    public long insertTitle(String isbn, String title, String publisher) 
    {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_ISBN, isbn);
        initialValues.put(KEY_TITLE, title);
        initialValues.put(KEY_PUBLISHER, publisher);
        return db.insert(DATABASE_TABLE, null, initialValues);
    }

    //---deletes a particular title---
    public boolean deleteTitle(long rowId) 
    {
        return db.delete(DATABASE_TABLE, KEY_ROWID + 
                "=" + rowId, null) > 0;
    }

    //---retrieves all the titles---
    public Cursor getAllTitles() 
    {
        return db.query(DATABASE_TABLE, new String[] {
                KEY_ROWID, 
                KEY_ISBN,
                KEY_TITLE,
                KEY_PUBLISHER}, 
                null, 
                null, 
                null, 
                null, 
                null);
    }

    //---retrieves a particular title---
    public Cursor getTitle(long rowId) throws SQLException 
    {
        Cursor mCursor =
                db.query(true, DATABASE_TABLE, new String[] {
                        KEY_ROWID,
                        KEY_ISBN, 
                        KEY_TITLE,
                        KEY_PUBLISHER
                        }, 
                        KEY_ROWID + "=" + rowId, 
                        null,
                        null, 
                        null, 
                        null, 
                        null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }

    //---updates a title---
    public boolean updateTitle(long rowId, String isbn, 
    String title, String publisher) 
    {
        ContentValues args = new ContentValues();
        args.put(KEY_ISBN, isbn);
        args.put(KEY_TITLE, title);
        args.put(KEY_PUBLISHER, publisher);
        return db.update(DATABASE_TABLE, args, 
                         KEY_ROWID + "=" + rowId, null) > 0;
    }
}

提前致谢

4

2 回答 2

1

在将值插入数据库之前您没有打开数据库，所以会出现这个错误，所以

写在下面的代码行

db.open();  // For Open Database

前

id = db.insertTitle(ISBN,Title,Publisher);  // For Insert value into Database

它会解决你的问题。

于 2012-12-15T08:51:20.483 回答
1

问题 ：：

在向数据库添加新值之前，您没有打开数据库

解决方案 ：：

首先更改打开数据库的代码：

db.open(); // open database here  before inserting 

id = db.insertTitle(ISBN,Title,Publisher);    

db.close(); //close database here  after inserting
于 2012-12-15T08:54:13.230 回答