android模拟器中的java.lang.NullPointerException

时间：2013-03-11 20:28:08

标签： android android-emulator runtimeexception

我正在创建一个应用程序，在其中我创建一个列表视图，其中包含两个文本字段和一个复选框....当我单击或选中复选框时，这两个文本都将添加到数据库中。但我的模拟器部队停止了我的申请。请提前帮助... thanx。

这是我的第一个名为Database2Activity的主要java类

package data.base;
import android.app.ListActivity;
import android.os.Bundle;
public class Database2Activity extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String[] str1 = new String[]{"Hari","Gopal","shayam","sita"};
    String[] str2 = new String[]{"123","2555","sksi","mahi"};
    setListAdapter(new Second(this, str1, str2));   
}
}

这是我的第二个名为Second.java的类

package data.base;

import com.example.phone_no.DBhelper;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.ImageView;
import android.widget.TextView;

public class Second extends ArrayAdapter<String> {
 String string1[];

 Context context;
    String string[];
     TextView textView;
    TextView textView1;

    CheckBox checkBox;
    EditText editText;
    public Second(Context context, String[] objects, String[] Object1)
    {

        super(context,R.layout.main, objects);

        this.context=context;
        this.string=objects;
        this.string1=Object1;
      //  this.imageView = Object3;
    }
    @Override
    public View getView(final int position, View convertView, ViewGroup parent)
    {

        LayoutInflater inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View view=inflater.inflate(R.layout.main,parent,false);
          textView=(TextView)view.findViewById(R.id.text1);


        textView1=(TextView)view.findViewById(R.id.text2);
       // imageView = (ImageView)view.findViewById(R.id.text3);
        textView.setText(string[position]);
        textView1.setText(string1[position]);

        checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
                // TODO Auto-generated method stub

                DBhelper DB = new DBhelper(context);
                DB.open();
                DB.adddata("A", string[position], string1[position]);
                DB.getAlldata();
                DB.close();


            }
        });

        return view;    //To change body of overridden methods use File | Settings | File Templates.

    }

}

这是我的第三类，名为DBhelper，它管理数据库操作

package com.example.phone_no;



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;
import android.util.Log;

public class DBhelper {
public static final String KEY_ID = "id";
public static final String KEY_NAME = "names";

public static final String KEY_PHONE = "phoneno";

private final Context ourContext;
private static final String DATABASE_TABLE = "Contactinfo";
private static final int DATABASE_VERSION = 27;
private static final String DATABASE_NAME = "contactdata.db";
private DbHelper ourHelper;
private SQLiteDatabase ourDatabase;
// end for location
private static class DbHelper extends SQLiteOpenHelper {
    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

        /*db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" + KEY_ID
                + " INTEGER PRIMARY KEY, " + KEY_NAME + " TEXT NULL , "
                + KEY_PHONE + " INTEGER NULL);");*/
        db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" + KEY_ID
                + " INTEGER , " + KEY_NAME + " TEXT NULL , "
                + KEY_PHONE + " INTEGER NULL);");

        // string value
        String y = "CREATE TABLE " + DATABASE_TABLE + " (" + KEY_ID
                + " INTEGER PRIMARY KEY  , " + KEY_NAME + " TEXT NULL , "
                + KEY_PHONE + " INTEGER NULL);";

        System.out.println("query" + y);
        Log.d("query", y);






    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
        // TODO Auto-generated method stub
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
        onCreate(db);

    }

}

public DBhelper(Context c) {
    ourContext = c;
}
public DBhelper open() throws SQLException 
{
    ourHelper = new DbHelper(ourContext);
    ourDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close() 
{
    ourHelper.close();
}
public long adddata(String id,String name,String number) 
{
    // TODO Auto-generated method stub
    // add the custom Image Gallery Image Path to Data Base
    ContentValues cv = new ContentValues();
    cv.put(KEY_ID, id);
    cv.put(KEY_NAME, name);
    cv.put(KEY_PHONE, number);
    return ourDatabase.insert(DATABASE_TABLE, null, cv);
}

public void getAlldata() 
{
    Cursor details = null;
    if (ourDatabase.isOpen() == false)

        ourDatabase = ourHelper.getWritableDatabase();
    if (ourDatabase.isOpen()) 
    {
        details = ourDatabase.query(DATABASE_TABLE, null, null, null, null, null, null);
         for(details.moveToFirst();!details.isAfterLast();details.moveToNext())
        {
             String a=details.getString(0);
            String b=details.getString(1);
            String c=details.getString(2);
            System.out.println("id--"+a+"name"+b+"phoneno"+c);
        }



    }


}
public long delete_image(String id) 
  {
    if (ourDatabase.isOpen() == false)
        ourDatabase = ourHelper.getWritableDatabase();
      if (ourDatabase.isOpen()) 
        {
            return ourDatabase.delete(DATABASE_TABLE, KEY_ID + "=" + id, null);
        }
        return 0;
    }



}

这是我的main.xml 

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

<EditText
android:layout_width="fill_parent" 
android:layout_height="wrap_content" 
android:id="@+id/edit"
/>
<Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button"
     />
  <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello"
        android:layout_weight="1"
        android:id="@+id/text1"
        />
<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello"
        android:layout_weight="1"
        android:id="@+id/text2"
        />
    <CheckBox
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:id="@+id/check"
            />



</LinearLayout>

这是Logcat Window按摩

03-12 02:04:21.028: D/AndroidRuntime(21905): Shutting down VM
03-12 02:04:21.028: W/dalvikvm(21905): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
03-12 02:04:21.308: E/AndroidRuntime(21905): FATAL EXCEPTION: main
03-12 02:04:21.308: E/AndroidRuntime(21905): java.lang.NullPointerException
03-12 02:04:21.308: E/AndroidRuntime(21905):    at data.base.Second.getView(Second.java:51)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.AbsListView.obtainView(AbsListView.java:1315)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.ListView.makeAndAddView(ListView.java:1727)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.ListView.fillDown(ListView.java:652)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.ListView.fillFromTop(ListView.java:709)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.ListView.layoutChildren(ListView.java:1580)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.AbsListView.onLayout(AbsListView.java:1147)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.view.View.layout(View.java:7035)
03-12 02:04:21.308: E/AndroidRuntime(21905):    at android.widget.FrameLayout.onLayout(FrameLayout.java:333)

最后这是我的清单

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

<uses-sdk android:minSdkVersion="8" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
        android:name=".Database2Activity"
        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="Second"/>
</application>

</manifest>

2 个答案:

答案 0 :(得分：2)

Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'

您需要在ListActivity的布局（main.xml）中使用ID为android:id="@android:id/list的ListView。

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);  // This layout must have a ListView

答案 1 :(得分：1)

从setContentView(R.layout.main);中删除onCreate - 您正在覆盖ListActivity（包含android.R.id.list元素）的默认视图，其中包含您的布局用于每个元素。

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