Question

我在sqlite中有一个数据库..它的DBAdapter类如下： package com.example.checkdb;

     import android.content.ContentValues;
     import android.content.Context;
     import android.database.Cursor;
     import android.database.SQLException;
     import android.database.sqlite.SQLiteDatabase;
     import android.database.sqlite.SQLiteOpenHelper;

    public class DBAdapter {

static final String KEY_ROWID="_id";
static final String KEY_NAME="name";
static final String KEY_EMAIL="email";
static final String TAG="DBAdapter";
static final String DATABASE_NAME="MyDB";
static final String DATABASE_TABLE="contacts";
static final int DATABASE_VERSION=1;
static final String DATABASE_CREATE="create table contacts"
        +"(_id integer primary key autoincrement,"
        +"name text not  null, email text not null);";

final Context context;
DatabaseHelper DBHelper;
SQLiteDatabase db;

public DBAdapter(Context context) {
    this.context=context;
    DBHelper=new DatabaseHelper(context);
    // TODO Auto-generated constructor stub
}

private static class DatabaseHelper extends SQLiteOpenHelper{

DatabaseHelper(Context context){
    super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL(DATABASE_CREATE);
}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    // TODO Auto-generated method stub

}

}

public DBAdapter open() throws SQLException{
    db=DBHelper.getWritableDatabase();
    return this;
}

public void close(){
    DBHelper.close();
}

public long insertContact(String name,String email){
    ContentValues initialValues= new ContentValues();
    initialValues.put(KEY_NAME, name);
    initialValues.put(KEY_EMAIL,email);
    return db.insert(DATABASE_TABLE, null, initialValues);
}

public boolean deleteContact(long rowId){
    return db.delete(DATABASE_TABLE, KEY_ROWID+"="+rowId, null)>0;
}

public Cursor getAllContacts(){
    return db.query(DATABASE_TABLE, new String[]{KEY_ROWID,KEY_NAME,KEY_EMAIL},
            null, null, null, null, null);
}

}

我的主要活动包含添加和显示联系人的按钮。它遵循这里： package com.example.checkdb;

     import android.app.Activity;
     import android.content.Intent;
     import android.os.Bundle;
     import android.view.Menu;
     import android.view.View;

    public class MainActivity extends Activity {

public static DBAdapter db;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    db=new DBAdapter(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

public void onAdd(View v){
    Intent i=new Intent(this,AddActivity.class);
    startActivity(i);
}

public void onShow(View v){
    Intent i=new Intent(this,ShowActivity.class);
    startActivity(i);
}

}

Show活动如下：

    package com.example.checkdb;

     import android.app.Activity;
     import android.database.Cursor;
     import android.os.Bundle;
     import android.widget.ListView;
     import android.widget.SimpleCursorAdapter;
     import android.widget.Toast;

     public class ShowActivity extends Activity{

public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_show);
    int i=0;
    try{
    ListView listView =(ListView)findViewById(R.id.list_contact);
    MainActivity.db.open();
    Cursor c=MainActivity.db.getAllContacts();
    MainActivity.db.close();

    String from[]=new String[]{DBAdapter.KEY_NAME};
    int to[]=new int[]{R.id.text_View_Name};

    SimpleCursorAdapter adapter;
    adapter=new SimpleCursorAdapter(this,R.layout.row_layout,
            c,from,to,i);
    listView.setAdapter(adapter);
    }
    catch(Exception e){
        Toast.makeText(this, "error",Toast.LENGTH_LONG).show();
    }

}
}

然后是我的activity_show.xml，我的布局文件是

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ListView
    android:id="@+id/list_contact"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >
</ListView>    

</LinearLayout>

每行的row_layout如下：

  <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/text_View_Name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout>

我的activity_main.xml文件如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<Button
    android:id="@+id/button_add"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="43dp"
    android:text="@string/add_butt" 
    android:onClick="onAdd" />

<Button
    android:id="@+id/button_show"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/button_add"
    android:layout_below="@+id/button_add"
    android:layout_marginTop="83dp"
    android:text="@string/show_butt"
    android:onClick="onShow"  />

  </RelativeLayout>

我的清单文件：

 <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.checkdb"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="19" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.checkdb.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

     <activity
        android:name="com.example.checkdb.AddActivity"
        android:label="@string/app_name"  />

     <activity
        android:name="com.example.checkdb.ShowActivity"
        android:label="@string/app_name"  />

     </application>

  </manifest>

现在，当我点击“显示”按钮时，我遇到了问题。模拟器关闭，不幸的是app已停止错误消息。请帮帮我......

不幸的是程序在android中使用简单的游标适配器时停止了错误

0 个答案: