Java – Add a button at the bottom of the preferences screen

Although @stealthcopter (check @Andrew’s answer) comment content in this question How to add a button to PreferenceScreen , I can’t see the button at the bottom of the activity.

Application .apk crashes with the following error: Unfortunately your_app has stopped working!

Here is the stack trace of the crash:

05-25 21:26:39.431: I/dalvikvm(1405): threadid=3: reacting to signal 3
05-25 21:26:39.462: I/dalvikvm(1405): Wrote stack traces to '/data/anr/traces.txt'
05-25 21:26:44.851: I/Process(1405): Sending signal. PID: 1405 SIG: 9
05-25 21:40:51.442: I/dalvikvm(1936): threadid=3: reacting to signal 3
05-25 21:40:51.601: I/dalvikvm(1936): Wrote stack traces to '/data/anr/traces.txt'
05-25 21:40:51.951: I/dalvikvm(1936): threadid=3: reacting to signal 3
05-25 21:40:52.001: I/dalvikvm(1936): Wrote stack traces to '/data/anr/traces.txt'
05-25 21:40:52.472: I/dalvikvm(1936): threadid=3: reacting to signal 3
05-25 21:40:52.561: I/dalvikvm(1936): Wrote stack traces to '/data/anr/traces.txt'
05-25 21:40:52.631: D/dalvikvm(1936): GC_CONCURRENT freed 172K, 4% free 9313K/9607K, paused 7ms+7ms
05-25 21:40:52.691: D/gralloc_goldfish(1936): Emulator without GPU emulation detected.
05-25 21:40:54.372: D/AndroidRuntime(1936): Shutting down VM
05-25 21:40:54.372: W/dalvikvm(1936): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
05-25 21:40:54.422: E/AndroidRuntime(1936): FATAL EXCEPTION: main
05-25 21:40:54.422: E/AndroidRuntime(1936): java.lang.RuntimeException: Unable to start activity ComponentInfo{com. DVA_HLUI/com. DVA_HLUI. DVA_HLUIPrefsActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android. R.id.list'
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.ActivityThread.startActivityNow(ActivityThread.java:1797)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:682)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.widget.TabHost.setCurrentTab(TabHost.java:346)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:150)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:540)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.view.View.performClick(View.java:3511)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.view.View$PerformClick.run(View.java:14105)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.os.Handler.handleCallback(Handler.java:605)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.os.Handler.dispatchMessage(Handler.java:92)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.os.Looper.loop(Looper.java:137)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.ActivityThread.main(ActivityThread.java:4424)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at java.lang.reflect.Method.invokeNative(Native Method)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at java.lang.reflect.Method.invoke(Method.java:511)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at dalvik.system.NativeStart.main(Native Method)
05-25 21:40:54.422: E/AndroidRuntime(1936): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android. R.id.list'
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.ListActivity.onContentChanged(ListActivity.java:243)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.preference.PreferenceActivity.onContentChanged(PreferenceActivity.java:944)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:254)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.Activity.setContentView(Activity.java:1835)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at com. DVA_HLUI. DVA_HLUIPrefsActivity.onCreate(DVA_HLUIPrefsActivity.java:15)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.Activity.performCreate(Activity.java:4465)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-25 21:40:54.422: E/AndroidRuntime(1936):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
05-25 21:40:54.422: E/AndroidRuntime(1936):     ... 18 more

This is the crashed Activity java class:

public class DVA_HLUIPrefsActivity extends PreferenceActivity 
{
   @Override
   public void onCreate(Bundle savedInstanceState) 
   { 
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.prefs);
        setContentView(R.layout.preferences);
   }
}

Here is its layout file:

<?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="vertical">

<ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" android:layout_weight="1">
    </ListView>

<LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

<Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Quit!" android:layout_weight="0.5"android:layout_gravity="center_vertical"
         />

<Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Help" android:layout_weight="0.5" android:layout_gravity="center_vertical"
         />

</LinearLayout>

</LinearLayout>

Finally, here is the preference XML resource:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

<Preference android:key="about" android:title="@string/titleAbout" android:summary="@string/summaryAbout" />

</PreferenceScreen>

Can you explain what the conflict is that causes the application to crash?

You must include a ListView with ID @android:id/list, as stated in the question you linked to (see ). Answer)。

Remove your <ListView from your android layout file (R.Layout.Preferences> and place it in place.

<ListView android:id="@android:id/list" 
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" />

This should fix the issue you’re experiencing.

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

EDIT: Just a few notes on the id property on the ListView. from Android XML Layouts

In XML tags, the syntax for IDs is:

android:id=”@+id/my_button”

The at sign (@) at the beginning of the string indicates that the XML parser should parse and extend the rest of the ID string and recognize it as an ID resource. A plus sign (+) indicates that this is a new resource name that must be created and added to our resource (in the R.java file). The Android framework also provides many other ID resources. When referencing an Android resource ID, you do not need a plus sign, but you must add the android package namespace as follows:

android:id=”@android:id/empty”

With the Android package namespace, we now download the Android package namespace. R resource class reference ID instead of local resource class.