Question

我在启动时从主要活动开始活动，并使用finish（）完成该活动。现在的问题是被调用的活动的内容是不可见的。下面是代码片段。

MainActivity onCreate（）

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

    Intent intent = new Intent(this, SplashActivity.class);
    startActivity(intent);
    // Set up the action bar.
    final ActionBar actionBar = getSupportActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    // When swiping between different sections, select the corresponding
    // tab. We can also use ActionBar.Tab#select() to do this if we have
    // a reference to the Tab.
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }
    });

    // For each of the sections in the app, add a tab to the action bar.
    for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
        // Create a tab with text corresponding to the page title defined by
        // the adapter. Also specify this Activity object, which implements
        // the TabListener interface, as the callback (listener) for when
        // this tab is selected.
        actionBar.addTab(
                actionBar.newTab()
                        .setText(mSectionsPagerAdapter.getPageTitle(i))
                        .setTabListener(this));
    }
}

SplashActivity onCreate（）

public class SplashActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_splash);
    //setContentView(R.layout.fragment_splash);
    try {
        Thread.sleep(5000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
    finish();
}

SplashActivity Fragment LAYOUT FILE

<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:gravity="center"
    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="com.example.daq.SplashActivity$PlaceholderFragment" >

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

     <ImageView
        android:id="@+id/imageView1"
        android:layout_width="192dp"
        android:layout_height="146dp"
        android:layout_gravity="center"
        android:contentDescription="@string/desc"
        android:src="@drawable/ic_launcher" />

</RelativeLayout>

SplashActivity activity_splash.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.daq.SplashActivity"
    tools:ignore="MergeRootFrame" >


</FrameLayout>

Android Manifest FIle

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.daq.MainActivity"
            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="com.example.daq.SplashActivity"
            android:label="@string/title_activity_splash"
            android:parentActivityName="com.example.daq.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.daq.MainActivity" />
        </activity>
    </application>

</manifest>

我不知道为什么在创建一个活动时会创建2个布局文件（fragment_splash.xml和activity_splash.xml）

我想提一下，代码可以正常运行，但是没有内容就显示了活动。

Answer 1

你可以先在MainActivity之后启动SplashActivity它会更好

Answer 2

一旦将片段放入容器中，就会调用finish（），因此活动将完成并返回调用它的活动。

public class SplashActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_splash);
    //setContentView(R.layout.fragment_splash);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }

    try {
        Thread.sleep(5000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }    
    finish();
}

具有文本字段和图像字段的相对布局不会显示在Android应用程序上

2 个答案: