java - 有人可以向我展示 PagerSlidingTabStrip 的简单工作实现吗？

Question

这是图书馆:https://github.com/astuetz/PagerSlidingTabStrip我正在尝试实现它，但我的应用程序在启动时一直崩溃。我试图理解发布的示例应用程序，但认为我做的不对。这是我的代码:

主 Activity .java

import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.graphics.drawable.TransitionDrawable;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

import com.astuetz.PagerSlidingTabStrip;


public class MainActivity extends FragmentActivity {

    private final Handler handler = new Handler();

    private PagerSlidingTabStrip tabs;
    private ViewPager pager;
    private MyPagerAdapter adapter;

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

        tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
        pager = (ViewPager) findViewById(R.id.pager);
        adapter = new MyPagerAdapter(getSupportFragmentManager());

        pager.setAdapter(adapter);

        tabs.setViewPager(pager);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
    }
    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState){
        super.onRestoreInstanceState(savedInstanceState);
    }

    private Drawable.Callback drawableCallback = new Drawable.Callback() {
        @Override
        public void invalidateDrawable(Drawable who) {
            getActionBar().setBackgroundDrawable(who);
        }

        @Override
        public void scheduleDrawable(Drawable who, Runnable what, long when) {
            handler.postAtTime(what, when);
        }

        @Override
        public void unscheduleDrawable(Drawable who, Runnable what) {
            handler.removeCallbacks(what);
        }
    };

    public class MyPagerAdapter extends FragmentPagerAdapter{
        private final String[] TITLES = {"T1","T2"};

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

        public CharSequence getPageTitle(int position){
            return TITLES[position];
        }
        @Override
        public Fragment getItem(int i) {
            return null;
        }

        @Override
        public int getCount() {
            return TITLES.length;
        }
    }
}

这里是activity_main.xml

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

    <com.astuetz.PagerSlidingTabStrip
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="48dip" />

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tabs"
        tools:context=".MainActivity" />


</RelativeLayout>

Answer 1

您没有在 FragmentPagerAdapter、getItem 方法中实例化任何您希望成为选项卡的 fragment 。相反，您将返回 null，因此没有 View 可以填充 viewpager。我可以看到您已经查看了他的示例项目，或许可以仔细查看您尝试添加到 viewpager 的 fragment 。上面的答案看起来是一个合理的实现。