Question

I am trying to do an intent from ShoutActivity that extends activity to MyListActivity that extends ListActivity on a Click

the App reaches when its reaches the intent

code:

first activity:

public class ShoutActivity extends Activity implements View.OnClickListener{
    /** Called when the activity is first created. */


private Button b1;
private Button b2;
private EditText text_box;



@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    b1 = (Button) this.findViewById(R.id.button1);
    b1.setOnClickListener(this);

    b2 = (Button) this.findViewById(R.id.button04);
    b2.setOnClickListener(this);
            //.....other stuff

}

public void onClick(View v) {
    if (v==b1)
    {   
        //not important
    }
        if(v==b2){

                Intent intent = new Intent();               

intent.setClass(ShoutActivity.this,MyListActivity.class);
);
                        Bundle myBundle = new Bundle();
                        myBundle.putStringArray("List", s1);
                        intent.putExtras(myBundle);
                        startActivity(intent);

        }
    }

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:weightSum="1">

    <EditText android:layout_width="match_parent" android:id="@+id/editText1" android:layout_height="wrap_content">
        <requestFocus></requestFocus>
    </EditText>
    <Button android:text="Shout !" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
    <Button android:text="View Shouts" android:id="@+id/button04" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>

</LinearLayout>

Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="karim.mobi"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ShoutActivity"
                  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=".MyListActivity" android:label="@string/app_name"
          android:theme="@android:style/Theme.NoTitleBar"/>

    </application>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
</manifest>

second activity

package karim.mobi;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.view.View;
import android.widget.*;
import android.app.*;

public class MyListActivity extends ListActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub

        super.onCreate(savedInstanceState);
        String s[];
        s= savedInstanceState.getStringArray("List");
        setListAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,s));
        getListView().setTextFilterEnabled(true);
    }

}

error logcat:

04-21 21:29:31.177: ERROR/AndroidRuntime(789): FATAL EXCEPTION: main
04-21 21:29:31.177: ERROR/AndroidRuntime(789): java.lang.RuntimeException: Unable to start activity ComponentInfo{karim.mobi/karim.mobi.MyListActivity}: java.lang.NullPointerException
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.os.Looper.loop(Looper.java:123)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread.main(ActivityThread.java:4627)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at java.lang.reflect.Method.invokeNative(Native Method)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at java.lang.reflect.Method.invoke(Method.java:521)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at dalvik.system.NativeStart.main(Native Method)
04-21 21:29:31.177: ERROR/AndroidRuntime(789): Caused by: java.lang.NullPointerException
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at karim.mobi.MyListActivity.onCreate(MyListActivity.java:21)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-21 21:29:31.177: ERROR/AndroidRuntime(789):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

can you please tell me whats the problem ?

please be specific

Answer 1

First, you must need to set content-view for your MyListActivity. So you need to call the following right after super.onCreate:

setContentView(R.layout.your_layout_name);

Second, you are reading the array wrong in that same activity.

Change this:

s= savedInstanceState.getStringArray("List");

To this:

s= getIntent().getExtras().getStringArray("List");