Android启动下一个活动失败

Question

我正在开发带有启动屏幕的android应用。 我希望另一个活动是启动闪屏后不久开始的选项卡轻扫，然后转到主活动。

当我运行以下代码时，我的启动屏幕运行良好，但随后该应用程序停止运行而未显示tabswiper或主要活动。 我应该如何更改代码才能使其正常工作？ 任何建议都将受到高度重视。

我的主要活动：MainActivity.java

package lk.sidadiya.sidadiya;

import android.os.Bundle;

import android.app.Activity;
import android.content.Intent;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        Intent i = new Intent(MainActivity.this, WelcomeScreen.class);
        startActivity(i);

        // close this activity
        finish();



    }

我的Tabswiper：WelcomeScreen.java

package lk.sidadiya.sidadiya;

import lk.sidadiya.tabswipe.adapter.TabsPagerAdapter;
import lk.sidadiya.sidadiya.R;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;


public class WelcomeScreen extends FragmentActivity implements
        ActionBar.TabListener {

    private ViewPager viewPager;
    private TabsPagerAdapter mAdapter;
    private ActionBar actionBar;
    // Tab titles
    private String[] tabs = { "Top Rated", "Games", "Movies" };



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initilization
        viewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
        mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

        viewPager.setAdapter(mAdapter);
        actionBar.setHomeButtonEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);       

        // Adding Tabs
        for (String tab_name : tabs) {
            actionBar.addTab(actionBar.newTab().setText(tab_name)
                    .setTabListener(this));
        }

        /**
         * on swiping the viewpager make respective tab selected
         * */
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

            @Override
            public void onPageSelected(int position) {
                // on changing the page
                // make respected tab selected
                actionBar.setSelectedNavigationItem(position);
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
            }
        });
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        // on tab selected
        // show respected fragment view
        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    }

}

我的初始屏幕：SplashScreen.java

package lk.sidadiya.sidadiya;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;

public class SplashScreen extends Activity {

    // Splash screen timer
    private static int SPLASH_TIME_OUT = 3000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);

        new Handler().postDelayed(new Runnable() {

            /*
             * Showing splash screen with a timer. This will be useful when you
             * want to show case your app logo / company
             */

            @Override
            public void run() {
                // This method will be executed once the timer is over
                // Start your app main activity
                Intent i = new Intent(SplashScreen.this, MainActivity.class);
                startActivity(i);

                // close this activity
                finish();
            }
        }, SPLASH_TIME_OUT);
    }

}

表现：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="lk.sidadiya.sidadiya"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >


         <!-- Splash screen -->

        <activity
            android:name="lk.sidadiya.sidadiya.SplashScreen"
            android:label="@string/app_name"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Black.NoTitleBar" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

         <!-- Welcome screen -->


        <activity
            android:name="lk.sidadiya.sidadiya.WelcomeScreen"
            android:label="@string/app_name"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Black" >

           <intent-filter>
                <action android:name="lk.sidadiya.sidadiya.WelcomeScreen" />

               <!-- <category android:name="android.intent.category.DEFAULT" /> -->
            </intent-filter>
        </activity>

        <!-- Main activity -->

        <activity
            android:name="lk.sidadiya.sidadiya.MainActivity"
            android:label="@string/app_name" >

             <intent-filter>
                <action android:name="android.intent.action.LAUNCHER" />

            </intent-filter>

        </activity>
         -->
    </application>

</manifest>

logcat的：

04-20 12:09:21.327: I/Process(1684): Sending signal. PID: 1684 SIG: 9
04-20 12:27:56.267: D/dalvikvm(1755): GC_FOR_ALLOC freed 54K, 5% free 2808K/2948K, paused 300ms, total 303ms
04-20 12:27:57.737: D/gralloc_goldfish(1755): Emulator without GPU emulation detected.
04-20 12:28:01.567: D/dalvikvm(1755): GC_FOR_ALLOC freed 9K, 3% free 3311K/3404K, paused 230ms, total 231ms
04-20 12:28:02.997: I/Choreographer(1755): Skipped 38 frames!  The application may be doing too much work on its main thread.
04-20 12:28:04.037: D/AndroidRuntime(1755): Shutting down VM
04-20 12:28:04.037: W/dalvikvm(1755): threadid=1: thread exiting with uncaught exception (group=0xb2ad3ba8)
04-20 12:28:04.187: E/AndroidRuntime(1755): FATAL EXCEPTION: main
04-20 12:28:04.187: E/AndroidRuntime(1755): Process: lk.sidadiya.sidadiya, PID: 1755
04-20 12:28:04.187: E/AndroidRuntime(1755): java.lang.RuntimeException: Unable to start activity ComponentInfo{lk.sidadiya.sidadiya/lk.sidadiya.sidadiya.WelcomeScreen}: java.lang.NullPointerException
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.os.Looper.loop(Looper.java:136)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at java.lang.reflect.Method.invokeNative(Native Method)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at java.lang.reflect.Method.invoke(Method.java:515)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at dalvik.system.NativeStart.main(Native Method)
04-20 12:28:04.187: E/AndroidRuntime(1755): Caused by: java.lang.NullPointerException
04-20 12:28:04.187: E/AndroidRuntime(1755):     at lk.sidadiya.sidadiya.WelcomeScreen.onCreate(WelcomeScreen.java:34)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.Activity.performCreate(Activity.java:5231)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-20 12:28:04.187: E/AndroidRuntime(1755):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-20 12:28:04.187: E/AndroidRuntime(1755):     ... 11 more

activity_main.xml中：

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>