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POAndroid -- Visible and Invisible Tabs: Button Handling
 

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  1. POAndroid -- Visible and Invisible Tabs: Button Handling
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    <p>I am trying to create an application with a login screen that appears and has effects among various other tabs.</p> <p>I have the tabbed implementation working fine: I can hide tabs and view the layouts of other tabs -- however, I cannot make them reappear. The program runs fine when I do not attempt button handling, but whenever I start my listener, I force-close.</p> <p>Attached is the problem code: I can't find exactly where I'm getting the force close from, but I do know it is in the button listener area.</p> <p>Essentially, I want the tabs to appear if the user's name and password are correct.</p> <p>What you are seeing is one of four tabs. Specifically, you are looking at the login screen tab.</p> <p>CODE:</p> <pre><code>public class LoginActivity extends Activity { TabHost tabHost = (TabHost) findViewById(android.R.id.tabhost); public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.login); final Button btn = (Button) findViewById(R.id.login_button); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { EditText txt_username = (EditText) findViewById(R.id.txt_username); EditText txt_password = (EditText) findViewById(R.id.txt_username); if (txt_username.toString().equals("Bob") &amp;&amp; txt_password.toString().equals("123")) { tabHost.getTabWidget().getChildAt(0) .setVisibility(View.VISIBLE); tabHost.getTabWidget().getChildAt(1) .setVisibility(View.VISIBLE); tabHost.getTabWidget().getChildAt(2) .setVisibility(View.VISIBLE); tabHost.getTabWidget().getChildAt(3) .setVisibility(View.GONE); } } }); } } </code></pre> <p>Attached is the logcat (very long)</p> <pre><code>04-12 17:07:31.465: ERROR/AndroidRuntime(1480): FATAL EXCEPTION: main 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): java.lang.RuntimeException: Unable to start activity ComponentInfo{android.waiter/android.waiter.waiter}: java.lang.RuntimeException: Unable to start activity ComponentInfo{android.waiter/android.waiter.LoginActivityGroup}: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{android.waiter/android.waiter.LoginActivity}: java.lang.NullPointerException 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.os.Handler.dispatchMessage(Handler.java:99) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.os.Looper.loop(Looper.java:123) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at android.app.ActivityThread.main(ActivityThread.java:4627) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at java.lang.reflect.Method.invokeNative(Native Method) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at java.lang.reflect.Method.invoke(Method.java:521) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 04-12 17:07:31.465: ERROR/AndroidRuntime(1480): at dalvik.system.NativeStart.main(Native Method) </code></pre>
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    1. PTQuestion
    1. USTshepang
    1. USBPuryear
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      1. LTLinked
    1. This table or related slice is empty.
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    1. COcan you show us your `logcat` output
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      1. POAndroid -- Visible and Invisible Tabs: Button Handling
      1. USTanmay Mandal
    2. COLogcat edited in.
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      1. POAndroid -- Visible and Invisible Tabs: Button Handling
      1. USBPuryear
    3. CO@Tanmay-Mandal, It appears I am having the same problem as: http://stackoverflow.com/questions/5316722/using-button-in-tab-layout-force-closes-application
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      1. POAndroid -- Visible and Invisible Tabs: Button Handling
      1. USBPuryear
 

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