Android Studio 中未显示 TabLayout 选项卡标题

Question

即使在我设置 app:tabTextColor 属性后，这些选项卡在应用程序中也能正常工作并显示正确的设计选项卡标题。

我很兴奋，因为在添加新代码时我在编辑器中看不到编辑进度。

Main-Class:

  enter code public class MainActivity extends AppCompatActivity {

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Create an instance of the tab layout from the view.
        TabLayout tabLayout = findViewById(R.id.tab_layout);
        // Set the text for each tab.
        tabLayout.addTab(tabLayout.newTab().setText(R.string.tab_label1));
        tabLayout.addTab(tabLayout.newTab().setText(R.string.tab_label2));
        tabLayout.addTab(tabLayout.newTab().setText(R.string.tab_label3));
        // Set the tabs to fill the entire layout.
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
        // Use PagerAdapter to manage page views in fragments.
        // Each page is represented by its own fragment.
        final ViewPager viewPager = findViewById(R.id.pager);
        final PagerAdapter adapter = new PagerAdapter(getSupportFragmentManager(),tabLayout.getTabCount());
        viewPager.setAdapter(adapter);
        // Setting a listener for clicks.
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
            }
        });
    }
}

寻呼机适配器：

  public class PagerAdapter extends FragmentStatePagerAdapter {


    private int mNumOfTabs;

    public PagerAdapter(FragmentManager fm, int NumberOfTabs) {
        super(fm);
        this.mNumOfTabs = NumberOfTabs;
    }

    @Override
    public Fragment getItem(int i) {
        switch (i) {
            case 0: return new TabFragment1();
            case 1: return new TabFragment2();
            case 2: return new TabFragment3();
            default: return null;
        }
    }

    @Override
    public int getCount() {
        return mNumOfTabs;
    }
}

在应用程序中： 当我启动应用程序时，一切看起来都符合我的预期。

XML 文件 主要activity 代码。片段文件看起来很好，我没有附加它们。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:background="@color/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

    <android.support.design.widget.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/toolbar"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:tabIndicatorColor="@color/design_default_color_primary_dark"
        app:tabTextColor="#eac086"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"
        android:layout_below="@id/tab_layout" />

</RelativeLayout

Android工作室看起来像：

Gradle 文件:

   android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.lateralnavigation"
        minSdkVersion 24
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

Answer 1

遗憾的是，预览编辑器无法判断您在 java/kotlin 代码中编写的内容。它从你的 xml 生成预览，你可以做的预览选项卡是将它们直接添加到 xml:

<android.support.design.widget.TabLayout
    android:id="@+id/tab_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/toolbar"
    android:background="?attr/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:tabIndicatorColor="@color/design_default_color_primary_dark"
    app:tabTextColor="#eac086">
  <android.support.design.widget.TabItem
     android:text="@string/tab_text"/>
  <android.support.design.widget.TabItem
     android:text="@string/tab_text"/>
 <android.support.design.widget.TabItem
     android:text="@string/tab_text"/>
</android.support.design.widget.TabLayout>

然而，这将改变您扩充布局的方式，因为选项卡已经在 xml 中。不需要做任何事情：

tabLayout.addTab(tabLayout.newTab().setText(R.string.tab_label1));

由于选项卡将位于 xml 中，您只需为其分配一个 ID 并使用 findViewById 实际访问该选项卡。如果您有固定数量的选项卡，您甚至可以使用：

tabLayout.getTabAt(position)

访问给定位置的选项卡。

Android Studio 中未显示 TabLayout 选项卡标题

TabLayout tabs title not displaying in Android Studio

android

android-studio

android-tablayout