运行后，Android应用程序显示黑屏

Question

When I click "Run as an Android Application" on Eclipse, the following is displayed in the console

[2014-06-05 20:07:18 - StudentConnect] Android Launch!
[2014-06-05 20:07:18 - StudentConnect] adb is running normally.
[2014-06-05 20:07:18 - StudentConnect] Performing sandhu.student.connect.SplashActivity activity launch
[2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0
[2014-06-05 20:07:18 - StudentConnect] Refreshing resource folders.
[2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0
[2014-06-05 20:07:18 - StudentConnect] Starting incremental Pre Compiler: Checking resource changes.
[2014-06-05 20:07:18 - StudentConnect] Nothing to pre compile!
[2014-06-05 20:07:18 - StudentConnect] Starting incremental Package build: Checking resource changes.
[2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0
[2014-06-05 20:07:18 - StudentConnect] Skipping over Post Compiler.
[2014-06-05 20:07:20 - StudentConnect] Application already deployed. No need to reinstall.
[2014-06-05 20:07:20 - StudentConnect] Starting activity sandhu.student.connect.SplashActivity on device 0f0898b2
[2014-06-05 20:07:21 - StudentConnect] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=sandhu.student.connect/.SplashActivity }
[2014-06-05 20:07:21 - StudentConnect] ActivityManager: Warning: Activity not started, its current task has been brought to the front

After deployed to my phone, it only displays a black screen. I recently implemented a splash screen, but it was working fine before; however I think it might have something to do with the problem. Here are my java and xml files:

MainActivity.java

package sandhu.student.connect;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends Activity {

    public WebView student_zangle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);  
        WebView student_zangle = (WebView) findViewById(R.id.student_zangle);
        student_zangle.loadUrl("https://zangleweb01.clovisusd.k12.ca.us/studentconnect/");
        student_zangle.setWebViewClient(new WebViewClient());
        student_zangle.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
        WebSettings settings = student_zangle.getSettings();
        settings.setJavaScriptEnabled(true);
        settings.setBuiltInZoomControls(true);      
        settings.setLoadWithOverviewMode(true);
        settings.setUseWideViewPort(true);
    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        WebView student_zangle = (WebView) findViewById(R.id.student_zangle);
        if ((keyCode == KeyEvent.KEYCODE_BACK) && student_zangle.canGoBack()) {
            student_zangle.goBack();
            return true;
        }
        else
        {
            finish();
        }
        return super.onKeyDown(keyCode, event);
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    android:background="@drawable/blue"
    tools:context=".MainActivity" >

    <WebView
        android:id="@+id/student_zangle"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

SplashActivity.java

package sandhu.student.connect;


import android.os.Bundle;
import android.preference.PreferenceActivity;

public class SplashActivity extends PreferenceActivity {

    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        addPreferencesFromResource(R.xml.prefs);
    }



 }

splash_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/blue"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="250dp"
        android:layout_height="100dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="145dp"
        android:contentDescription="@string/zangle_logo"
        android:src="@drawable/logo" />

</RelativeLayout>

Also, here is a full copy of the logcat error output:

06-05 20:19:46.698: E/Watchdog(817): !@Sync 1952
06-05 20:20:09.971: E/memtrack(16438): Couldn't load memtrack module (No such file or directory)
06-05 20:20:09.971: E/android.os.Debug(16438): failed to load memtrack module: -2
06-05 20:20:11.012: E/memtrack(16451): Couldn't load memtrack module (No such file or directory)
06-05 20:20:11.012: E/android.os.Debug(16451): failed to load memtrack module: -2
06-05 20:20:11.202: E/EnterpriseContainerManager(817): ContainerPolicy Service is not yet ready!!!

Please help me figure out what is wrong, or at least point me in the right direction. Thanks in advance.

Answer 1

This message :"ActivityManager: Warning: Activity not started, its current task has been brought to the front" means adb is detecting that the same app is already deployed, so it just bring the app in front. You can try to remove it from your phone or launch it in debug it you want the app to be redeployed.

Try to clean project if you are that the app is not up to date on the phone.

Answer 2

It is not an error message, it is a warning. What the system is trying to tell you: The application on the device is the same as your application in Eclipse. And because the application is already running on the device (recompilation will not be done if you have not changed the code , it doesn't go through the uninstall-install process), the system tells you that it is not going to kill and restart it, but bring the activity of your already running app into the foreground. This is pretty normal.

The warning will not continue if you edit your code and run it (because the app is then killed, reinstalled and started).

I do get this warning many times, I use a lame technique. Add a space anywhere in your code (in any file). Just Save the project and run. It will then go through the uploading and installing process again. This is the easiest way to go about it without actually changing any code that matters.