列表视图中的联系人

Question

1. I am making an app in which i need to read contacts and send text message.I am able to read the contacts but i am unable to show the contacts name and no in list View.

2. when i try to set C_number my app crashes.

3. And i want to send the sms to selected contacts.

Any help to cater my problems thanks.

This is single_listview_item.xml

    <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"
   >
    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent">
    <CheckBox
        android:id="@+id/chk_box"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"/>

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/chk_box"
        android:textStyle="bold"/>
    <TextView
        android:id="@+id/number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/name"
        android:layout_toRightOf="@id/chk_box"
        android:textStyle="italic"
        android:textSize="12sp"/>
        </LinearLayout>
    </ScrollView>
</RelativeLayout>

This is the main activity where i read all the contacts and i am trying to set them to list view . I have searched a lot but i am unable to find the correct solution. Any to get me going .

This is Mainactivity.java

    package chypher.listviewexample;

import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.provider.ContactsContract;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Switch;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends ActionBarActivity implements CompoundButton.OnCheckedChangeListener {
    ListView lv;
    ArrayList<Planet> planetlist;
    contactadapter cadapter;
    Button okbtn;
    public String name;
    public String phoneNumber;
   public List<String> numb= new ArrayList<String>();;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        lv=(ListView)findViewById(R.id.listview);

        fetchContacts();

        //fetchContacts();


    }

    private void fetchContacts() {
       // int phoneNumber ;

 int i=0;
        Uri CONTENT_URI = ContactsContract.Contacts.CONTENT_URI;
        String _ID = ContactsContract.Contacts._ID;
        String DISPLAY_NAME = ContactsContract.Contacts.DISPLAY_NAME;
        String HAS_PHONE_NUMBER = ContactsContract.Contacts.HAS_PHONE_NUMBER;

        Uri PhoneCONTENT_URI = ContactsContract.CommonDataKinds.Phone.CONTENT_URI;
        String Phone_CONTACT_ID = ContactsContract.CommonDataKinds.Phone.CONTACT_ID;
        String NUMBER = ContactsContract.CommonDataKinds.Phone.NUMBER;



      List<String>output = new ArrayList<String>();
        List<String>outputnum=new ArrayList<String>();

        ContentResolver contentResolver = getContentResolver();

        Cursor cursor = contentResolver.query(CONTENT_URI, null,null, null, null);
        // Loop for every contact in the phone
        if (cursor.getCount() > 0) {

            while (cursor.moveToNext()) {

                String contact_id = cursor.getString(cursor.getColumnIndex( _ID ));
               name = cursor.getString(cursor.getColumnIndex( DISPLAY_NAME ));

               // System.out.println("checking from phonename variable"+fromphonename);
                int hasPhoneNumber = Integer.parseInt(cursor.getString(cursor.getColumnIndex( HAS_PHONE_NUMBER )));

                if (hasPhoneNumber > 0) {

                    output.add(name);

                    // Query and loop for every phone number of the contact
                    Cursor phoneCursor = contentResolver.query(PhoneCONTENT_URI, null, Phone_CONTACT_ID + " = ?", new String[] { contact_id }, null);

                    while (phoneCursor.moveToNext()) {
                        phoneNumber = phoneCursor.getString(phoneCursor.getColumnIndex(NUMBER));
                        outputnum.add( phoneNumber);

                       // System.out.println("cursor phoneno:"+phoneNumber);
                    System.out.println("i value:"+i);
                        i++;
                        displayPlanetList(name,phoneNumber);
                    }

                    phoneCursor.close();
                }




            }
            System.out.println("read from phone:"+output.size());
            System.out.println("read from num:"+outputnum.size());

        }

    }

    private void displayPlanetList(String nam,String nm) {


        planetlist =new ArrayList<Planet>();

        planetlist.add(new Planet(nam,nm));



        cadapter=new contactadapter(planetlist,this);

        lv.setAdapter(cadapter);
    }


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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        switch (item.getItemId()) {
            case R.id.action_next:
                System.out.println("selected are :" + numb);
                break;
        }

       return true;

    }

    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        int pos=lv.getPositionForView(buttonView);
        if(pos!=ListView.INVALID_POSITION){
            Planet p=planetlist.get(pos);
            p.setSelected(isChecked);

            Toast.makeText(this,"Clicked on planet:" +p.getName()+" : state :"+isChecked,Toast.LENGTH_SHORT).show();

            numb.add(p.getNumber());



        }
    }
}

This is my contact adapter class .

  package chypher.listviewexample;

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.TextView;

import java.util.List;

/**
 * Created by Saqlain Haider on 6/13/2015.
 */
class Planet{
    String name;
    String number;
    boolean selected=false;
    public Planet(String name,String number){
        super();
        this.name=name;
        this.number=number;
    }

    public boolean isSelected() {
        return selected;
    }

    public void setSelected(boolean selected) {
        this.selected = selected;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
public class contactadapter extends ArrayAdapter<Planet> {
    private List<Planet>planetList;
    private Context context;
    public contactadapter(List<Planet> planetList, Context context) {
        super(context, R.layout.single_listview_item,planetList);
        this.planetList=planetList;
        this.context=context;
    }
    private static class planetholder{
        public TextView cName,Cnumber;
        public CheckBox checkBox;
    }
    @Override
    public View getView(int position,View convertView,ViewGroup parent){

        View v=convertView;
        planetholder holder=new planetholder();
        if(convertView==null){
            LayoutInflater inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v=inflater.inflate(R.layout.single_listview_item,null);
            holder.cName=(TextView)v.findViewById(R.id.name);
            holder.Cnumber=(TextView)v.findViewById(R.id.number);
            holder.checkBox=(CheckBox)v.findViewById(R.id.chk_box);
            holder.checkBox.setOnCheckedChangeListener((MainActivity)context);


        }
        else
        {
            holder=(planetholder)v.getTag();
        }
        Planet p=planetList.get(position);
        holder.cName.setText(p.getName());
        holder.Cnumber.setText(p.getNumber());
        holder.checkBox.setChecked(p.isSelected());
        holder.checkBox.setTag(p);
        return v;
    }
}

This is simple main.xml containing listview

 <?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">
    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>

</LinearLayout>

error log:

06-14 00:01:59.972  10362-10362/chypher.listviewexample E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
        at chypher.listviewexample.contactadapter.getView(contactadapter.java:82)
        at android.widget.AbsListView.obtainView(AbsListView.java:2063)
        at android.widget.ListView.makeAndAddView(ListView.java:1792)
        at android.widget.ListView.fillDown(ListView.java:676)
        at android.widget.ListView.fillGap(ListView.java:640)
        at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4901)
        at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:2923)
        at android.widget.AbsListView.startScrollIfNeeded(AbsListView.java:2868)
        at android.widget.AbsListView.onInterceptTouchEvent(AbsListView.java:3738)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1639)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2019)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1754)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1928)
        at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1387)
        at android.app.Activity.dispatchTouchEvent(Activity.java:2388)
        at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:59)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1876)
        at android.view.View.dispatchPointerEvent(View.java:5733)
        at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3104)
        at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2666)
        at android.view.ViewRootImpl.processInputEvents(ViewRootImpl.java:900)
        at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2675)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4666)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
        at dalvik.system.NativeStart.main(Native Method)

updated error log:

    06-14 01:24:17.271  14698-14698/chypher.listviewexample W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40e4c258)
06-14 01:24:17.305  14698-14698/chypher.listviewexample E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at android.widget.AdapterView.getPositionForView(AdapterView.java:594)
            at chypher.listviewexample.MainActivity.onCheckedChanged(MainActivity.java:153)
            at android.widget.CompoundButton.setChecked(CompoundButton.java:125)
            at chypher.listviewexample.contactadapter.getView(contactadapter.java:84)
            at android.widget.AbsListView.obtainView(AbsListView.java:2063)
            at android.widget.ListView.makeAndAddView(ListView.java:1792)
            at android.widget.ListView.fillUp(ListView.java:709)
            at android.widget.ListView.fillGap(ListView.java:649)
            at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4901)
            at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:4074)
            at android.os.Handler.handleCallback(Handler.java:605)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4666)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

The problem is, that you're never setting your planetholder (which should really be written in camel-case) as the tag of the item-view.

This is okay for the first items, since they'll need to be inflated anyways. As soon as you start scrolling and the inflated views are re-used, you run into this block:

} else {
  holder=(planetholder)v.getTag();
}

Since the tag is never set on v , v.getTag() will return null . In Java, you can cast null to anything (see this discussion ), which causes holder to be null .

Now, when you call holder.cName , you're trying to access a property on a null -reference, which causes the NullPointerException .

The fix is to change this:

holder.checkBox.setTag(p);

to this:

v.setTag(holder);