如何使用不同的片段/布局实现ViewPager

Question

当我启动一个实现viewpager的活动时,viewpager创建了各种片段.我想为每个片段使用不同的布局,但问题是viewpager在最大值时只显示两个布局(在1之后的所有剩余片段上的第二个布局).

以下是实现viewpager的SwipeActivity的代码:

public class SwipeActivity extends FragmentActivity
{

    MyPageAdapter pageAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_swipe);
        pageAdapter = new MyPageAdapter(getSupportFragmentManager());
        ViewPager pager=(ViewPager)findViewById(R.id.pager);
        pager.setAdapter(pageAdapter);
        ActionBar bar = getActionBar();
        bar.setDisplayHomeAsUpEnabled(true);
    }
    /**
    * Custom Page adapter
    */
    private class MyPageAdapter extends FragmentPagerAdapter
    {
        public MyPageAdapter(FragmentManager fm)
        {
            super(fm);
        }
        @Override
        public int getCount()
        {
            return 5;
        }
        @Override
        public Fragment getItem(int position)
        {
            switch(position)
            {
                case 0: return new MyFragment();
                case 1: return SecondFragment.newInstance("asdasd");
                default : return RamFragment.newInstance("s");
            }
        }
     }
}

这是片段的代码

public class MyFragment extends Fragment
{
   @Override
   public View onCreateView(LayoutInflater paramLayoutInflater, ViewGroup paramViewGroup,    Bundle paramBundle)
   {
     return paramLayoutInflater.inflate(R.layout.processorlayout, paramViewGroup, false);
   }
}

我使用了这样的5个片段,它们都有不同的布局,但是viewpager最多只显示2个.

编辑:SecondFragment的代码

public class SecondFragment extends Fragment
{
   public static final String EXTRA_MESSAGE = "EXTRA_MESSAGE";

  public static final SecondFragment newInstance(String paramString)
  {
    SecondFragment f = new SecondFragment();
    Bundle localBundle = new Bundle(1);
    localBundle.putString("EXTRA_MESSAGE", paramString);
    f.setArguments(localBundle);
    return f;
  }

  @Override
  public View onCreateView(LayoutInflater paramLayoutInflater, ViewGroup paramViewGroup, Bundle paramBundle)
  {
     return paramLayoutInflater.inflate(R.layout.motherboardlayout, paramViewGroup, false);
  }
}

Answer 1

由于这是一个非常常见的问题,我想花时间和精力详细解释具有多个碎片和布局的ViewPager.干得好.

具有多个片段和布局文件的ViewPager - 如何操作

以下是如何使用不同的片段类型和不同的布局文件实现ViewPager的完整示例.

在这种情况下,我有3个Fragment类,每个类有不同的布局文件.为了简单起见,片段布局仅在背景颜色上有所不同.当然,任何布局文件都可以用于片段.

FirstFragment.java具有橙色背景布局,SecondFragment.java具有绿色背景布局,ThirdFragment.java具有红色背景布局.此外,每个片段显示不同的文本,具体取决于它来自哪个类以及它是哪个实例.

还要注意我使用的是支持库的片段: android.support.v4.app.Fragment

MainActivity.java(初始化Viewpager并将其作为内部类的适配器).再看看进口.我正在使用这个android.support.v4包.

import android.os.Bundle;
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;

public class MainActivity extends FragmentActivity {

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

        ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
        pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
    }

    private class MyPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int pos) {
            switch(pos) {

            case 0: return FirstFragment.newInstance("FirstFragment, Instance 1");
            case 1: return SecondFragment.newInstance("SecondFragment, Instance 1");
            case 2: return ThirdFragment.newInstance("ThirdFragment, Instance 1");
            case 3: return ThirdFragment.newInstance("ThirdFragment, Instance 2");
            case 4: return ThirdFragment.newInstance("ThirdFragment, Instance 3");
            default: return ThirdFragment.newInstance("ThirdFragment, Default");
            }
        }

        @Override
        public int getCount() {
            return 5;
        }       
    }
}

activity_main.xml(MainActivitys .xml文件) - 一个简单的布局文件,仅包含填充整个屏幕的ViewPager.

<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/viewPager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    />

Fragment类,FirstFragment.java 导入android.support.v4.app.Fragment;

public class FirstFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.first_frag, container, false);

        TextView tv = (TextView) v.findViewById(R.id.tvFragFirst);
        tv.setText(getArguments().getString("msg"));

        return v;
    }

    public static FirstFragment newInstance(String text) {

        FirstFragment f = new FirstFragment();
        Bundle b = new Bundle();
        b.putString("msg", text);

        f.setArguments(b);

        return f;
    }
}

first_frag.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/holo_orange_dark" >

    <TextView
        android:id="@+id/tvFragFirst"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:textSize="26dp"
        android:text="TextView" />
</RelativeLayout>

SecondFragment.java

public class SecondFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.second_frag, container, false);

    TextView tv = (TextView) v.findViewById(R.id.tvFragSecond);
    tv.setText(getArguments().getString("msg"));

    return v;
}

public static SecondFragment newInstance(String text) {

    SecondFragment f = new SecondFragment();
    Bundle b = new Bundle();
    b.putString("msg", text);

    f.setArguments(b);

    return f;
}
}

second_frag.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/holo_green_dark" >

    <TextView
        android:id="@+id/tvFragSecond"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:textSize="26dp"
        android:text="TextView" />

</RelativeLayout>

ThirdFragment.java

public class ThirdFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.third_frag, container, false);

    TextView tv = (TextView) v.findViewById(R.id.tvFragThird);      
    tv.setText(getArguments().getString("msg"));

    return v;
}

public static ThirdFragment newInstance(String text) {

    ThirdFragment f = new ThirdFragment();
    Bundle b = new Bundle();
    b.putString("msg", text);

    f.setArguments(b);

    return f;
}
}

third_frag.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/holo_red_light" >

    <TextView
        android:id="@+id/tvFragThird"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:textSize="26dp"
        android:text="TextView" />

</RelativeLayout>

最终结果如下:

Viewpager包含5个Fragments,Fragments 1是FirstFragment类型,并显示first_frag.xml布局,Fragment 2是SecondFragment类型并显示second_frag.xml,Fragment 3-5是ThirdFragment类型并且都显示third_frag.xml .

在上面你可以看到5片段之间可以通过向左或向右滑动切换.当然,只能在同一时间显示一个片段.

最后但并非最不重要的:

我建议你在每个Fragment类中使用一个空构造函数.

不是通过构造函数移交潜在参数,而是使用newInstance(...)方法和Bundle交换参数.

这种方式如果分离并重新附加对象状态,则可以通过参数存储.非常喜欢Bundles附加Intents.

phi非常友好地指出示例代码在GitHub上,可以在这里查看.

Answer 2

创建一个视图数组并将其应用于: container.addView(viewarr[position]);

public class Layoutes extends PagerAdapter {

    private Context context;
    private LayoutInflater layoutInflater;
    Layoutes(Context context){
        this.context=context;
    }
    int layoutes[]={R.layout.one,R.layout.two,R.layout.three};
    @Override
    public int getCount() {
        return layoutes.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return (view==(LinearLayout)object);
    }
    @Override
    public Object instantiateItem(ViewGroup container, int position){
        layoutInflater=(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View one=layoutInflater.inflate(R.layout.one,container,false);
        View two=layoutInflater.inflate(R.layout.two,container,false);
        View three=layoutInflater.inflate(R.layout.three,container,false);
        View viewarr[]={one,two,three};
        container.addView(viewarr[position]);
        return viewarr[position];
    }
    @Override
    public void destroyItem(ViewGroup container, int position, Object object){
        container.removeView((LinearLayout) object);
    }

}

Answer 3

添加片段的代码

public Fragment getItem(int position) {

    switch (position){
        case 0:
            return new Fragment1();

        case 1:
            return new Fragment2();

        case 2:
            return new Fragment3();

        case 3:
            return new Fragment4();

        default:
            break;
    }

    return null;
}

为每个片段创建一个 xml 文件，例如 Fragment1，使用 fragment_one.xml 作为布局文件，在 Fragment1 java 文件中使用以下代码。

public class Fragment1 extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_one, container, false);

        return view;

    }
}

稍后您可以进行必要的更正。它对我有用。