Android 滑动片段无效

Question

中的开发人员指南

这真的很令人困惑，因为并非所有内容都是最新的，并且网站上的大多数指南都已过时并且许多方法已被弃用。所以我只剩下 AppCompatActivity 和 FragmentStatePagerAdapter 等所有这些新事物。

无论如何，我已经尽力了，但我仍然无法在我的片段之间滑动，我不明白为什么。这里要注意一点，我尽量不使用制表符。

我也讨厌发布大块代码，但为了将来参考，这可能很重要，所以请随时从我的 github project

中查看整个代码

MainActivity

public class MainActivity extends AppCompatActivity {
    private Toolbar toolbar;
    private Drawer drawer;

    private ViewPager viewPager;
    private PagerAdapter pagerAdapter;

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

        //initTabLayout(); --> needed?
        toolbar =(Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        initViewPager();
        initMaterialDrawer();
    }

    private void initViewPager() {
        viewPager = (ViewPager) findViewById(R.id.pager);
        pagerAdapter = new CustomPagerAdapter(getSupportFragmentManager(),CustomPagerAdapter.mNumOfTabs);
        viewPager.setAdapter(pagerAdapter);
    }

    @Override
    public void onBackPressed() {
        if(drawer != null && drawer.isDrawerOpen())
            drawer.closeDrawer();
        else
            super.onBackPressed();
    }
    private void initMaterialDrawer() {
        PrimaryDrawerItem item1 = new PrimaryDrawerItem().withName("Profile");
        PrimaryDrawerItem item2 = new PrimaryDrawerItem().withName("Organisations");
        PrimaryDrawerItem item3 = new PrimaryDrawerItem().withName("Extra Option");
        PrimaryDrawerItem item4 = new PrimaryDrawerItem().withName("Extra Option");

        AccountHeader headerResult = new AccountHeaderBuilder()
                .withActivity(this)
                .withHeaderBackground(R.drawable.drawer_background1)
                .withAlternativeProfileHeaderSwitching(false)
                .addProfiles(
                        new ProfileDrawerItem()
                                .withIsExpanded(false)
                                .withName("name here")
                                .withEmail("emailhere.com")
                                .withEnabled(false)
                                .withIcon(new IconDrawable(this, FontAwesomeIcons.fa_reddit))
                )
                .withOnAccountHeaderListener(new AccountHeader.OnAccountHeaderListener() {

                    @Override
                    public boolean onProfileChanged(View view, IProfile profile, boolean current) {
                        return false;
                    }
                })
                .build();

        //create the drawer and remember the `Drawer` result object
        drawer = new DrawerBuilder()
                .withActivity(this)
                .withToolbar(toolbar)
                .withAccountHeader(headerResult)
                .withTranslucentStatusBar(true)
                .addDrawerItems(
                        new PrimaryDrawerItem().withName("111111111").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new PrimaryDrawerItem().withName("111111111").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new PrimaryDrawerItem().withName("111111111").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new SectionDrawerItem().withName("SECTION"),
                        new SecondaryDrawerItem().withName("22222").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new SecondaryDrawerItem().withName("22222").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new SecondaryDrawerItem().withName("22222").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out)),
                        new SecondaryDrawerItem().withName("22222").withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out))
                )
                .withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() {
                    @Override
                    public boolean onItemClick(View view, int position, IDrawerItem drawerItem) {
                        if (drawerItem instanceof Nameable) {
                            Toast.makeText(MainActivity.this, ((Nameable) drawerItem).getName().getText(MainActivity.this), Toast.LENGTH_SHORT).show();
                        }
                        //true: do nothing
                        //false: close drawer
                        return true;
                    }
                }).build();

        drawer.addStickyFooterItem(new PrimaryDrawerItem()
                        .withName("Log out")
                        .withIcon(new IconDrawable(this, FontAwesomeIcons.fa_sign_out).alpha(100)));

        getSupportActionBar().setDisplayHomeAsUpEnabled(false);
        drawer.getActionBarDrawerToggle().setDrawerIndicatorEnabled(true);
    }
}

主布局

<?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"
    tools:context="be.kdg.kandoe.kandoe.activity.MainActivity">
    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar">
    </include>
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="MAINACTIVITY"
        android:id="@+id/main_title"
        android:layout_below="@+id/toolbar"
        android:layout_alignParentStart="true" />

</RelativeLayout>

PagerAdapter

public class CustomPagerAdapter extends FragmentStatePagerAdapter {
    public static int mNumOfTabs;

    public CustomPagerAdapter(FragmentManager fm, int NumOfTabs) {
        super(fm);
        this.mNumOfTabs = NumOfTabs;
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new ChatFragment();
            case 1:
                return new GameFragment();
            case 2:
                return new CardFragment();
            default:
                return null;
        }
    }

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

Answer 1

 pagerAdapter = new CustomPagerAdapter(getSupportFragmentManager(),CustomPagerAdapter.mNumOfTabs);

mNumOfTabs 未在 CustomPagerAdapter

中初始化

你需要这样做..

 pagerAdapter = new CustomPagerAdapter(getSupportFragmentManager(),3);

或

public class CustomPagerAdapter extends FragmentStatePagerAdapter {

    public CustomPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new ChatFragment();
            case 1:
                return new GameFragment();
            case 2:
                return new CardFragment();
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        return 3;
    }
}

适配器是这样设置的

pagerAdapter = new CustomPagerAdapter(getSupportFragmentManager());

并且您的主布局需要具有垂直方向的 LinearLayout 以获得完美的外观。在将其更改为

之前，通过使用现有代码来查看差异

Android 滑动片段无效

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