FragmentActivity没有显示片段的正确布局

我尝试了第一次在android中的碎片，我使用FragmentPagerAdapter为有限数量的碎片，在这种情况下3.唯一的问题是，当我刷卡时，它会进入第二个和第三个页面，但每次显示第一个片段的布局，而不是另一个。FragmentActivity没有显示片段的正确布局

MainActivity.java：

package com.example.swipetabtest; 

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; 
import android.support.v4.view.ViewPager.OnPageChangeListener; 
import android.widget.Toast; 

public class MainActivity extends FragmentActivity { 
    FragmentPagerAdapter adapterViewPager; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     ViewPager vpPager = (ViewPager) findViewById(R.id.vpPager); 
     adapterViewPager = new MyPagerAdapter(getSupportFragmentManager()); 
     vpPager.setAdapter(adapterViewPager); 
    } 

    public static class MyPagerAdapter extends FragmentPagerAdapter { 
    private static int NUM_ITEMS = 3; 

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

     // Returns total number of pages 
     @Override 
     public int getCount() { 
      return NUM_ITEMS; 
     } 

     // Returns the fragment to display for that page 
     @Override 
     public Fragment getItem(int position) { 
      switch (position) { 
      case 0: 
       return FirstFragment.newInstance(0, "Page # 1"); 
      case 1: 
       return SecondFragment.newInstance(1, "Page # 2"); 
      case 2: 
       return ThirdFragment.newInstance(2, "Page # 3"); 
      default: 
       return null; 
      } 
     } 

    } 

}

FirstFragment.java

package com.practice.swipetabtest; 

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

public class FirstFragment extends Fragment { 
    // Store instance variables 
    private String title; 
    private int page; 

    // newInstance constructor for creating fragment with arguments 
    public static FirstFragment newInstance(int page, String title) { 
     FirstFragment fragmentFirst = new FirstFragment(); 
     Bundle args = new Bundle(); 
     args.putInt("someInt", page); 
     args.putString("someTitle", title); 
     fragmentFirst.setArguments(args); 
     return fragmentFirst; 
    } 

    // Store instance variables based on arguments passed 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     page = getArguments().getInt("someInt", 0); 
     title = getArguments().getString("someTitle"); 
    } 

    // Inflate the view for the fragment based on layout XML 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View view = inflater.inflate(R.layout.fragment_first, container, false); 
     return view; 
    } 
}

SecondFragment.java

package com.practice.swipetabtest; 

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 

public class SecondFragment extends Fragment { 
    // Store instance variables 
    private String title; 
    private int page; 

    // newInstance constructor for creating fragment with arguments 
    public static FirstFragment newInstance(int page, String title) { 
     FirstFragment fragmentFirst = new FirstFragment(); 
     Bundle args = new Bundle(); 
     args.putInt("someInt", page); 
     args.putString("someTitle", title); 
     fragmentFirst.setArguments(args); 
     return fragmentFirst; 
    } 

    // Store instance variables based on arguments passed 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     page = getArguments().getInt("someInt", 1); 
     title = getArguments().getString("someTitle"); 
    } 

    // Inflate the view for the fragment based on layout XML 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View view = inflater.inflate(R.layout.fragment_second, container, false); 
     return view; 
    } 
}

ThirdFragment.java

package com.practice.swipetabtest; 

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

public class ThirdFragment extends Fragment { 
    // Store instance variables 
    private String title; 
    private int page; 

    // newInstance constructor for creating fragment with arguments 
    public static FirstFragment newInstance(int page, String title) { 
     FirstFragment fragmentFirst = new FirstFragment(); 
     Bundle args = new Bundle(); 
     args.putInt("someInt", page); 
     args.putString("someTitle", title); 
     fragmentFirst.setArguments(args); 
     return fragmentFirst; 
    } 

    // Store instance variables based on arguments passed 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     page = getArguments().getInt("someInt", 2); 
     title = getArguments().getString("someTitle"); 
    } 

    // Inflate the view for the fragment based on layout XML 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View view = inflater.inflate(R.layout.fragment_third, container, false); 
     return view; 
    } 
}

activity_main.xml中：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical"> 

    <android.support.v4.view.ViewPager 
     android:id="@+id/vpPager" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"> 
    </android.support.v4.view.ViewPager> 
</LinearLayout>

fragment_first.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

    <TextView 
     android:text="this is the first fragment" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content"/> 
</LinearLayout>

fragment_second.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

    <TextView 
     android:text="this is the second fragment" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" /> 
</LinearLayout>

fragment_third.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

    <TextView 
     android:text="hey look a third fragment" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" /> 
</LinearLayout>

我试图检查是否正确的布局是否正在充气每个片段和开关语句套管到正确的片段，但他们看起来也没关系，我也...

但它始终显示第一个片段的布局。

来源

2014-02-16 user2405469

的问题是，如果你看一看到您FirstFragment，SecondFragment和ThirdFragment类instantiateFragment方法，你实际上是在他们三个人都创造FirstFragment的新实例。

要调用：

 FirstFragment fragmentFirst = new FirstFragment();

在所有三个你上课时，你应该调用的：

 SecondFragment fragmentSecond = new SecondFragment();

或

 ThirdFragment fragmentThird = new ThirdFragment();

取决于哪个类，你都在

来源

2014-02-16 11:44:23 Matej

我知道这是明显的事情...从FirstFragment.java复制和粘贴，而不是重命名返回正确的类型...谢谢你这工作:: ） – user2405469

@ user2405469不客气！复制和废物是更合适的描述。我只是从来没有做过复制/粘贴代码或XML，正是因为一些不好的经历，当我失去了几个小时试图解决某些问题时才发现它是一个简单的复制/粘贴问题。 – Matej

@Matej ...你是对的，在我的编码经验中尽早采纳这个建议，并摆脱这个习惯:) – user2405469

@Override 
     public Fragment getItem(int position) { 
      switch (position) 
      { 
       Fragment frag=null; 
     if(position==0) 
      frag=new FirstFragment(); 
     if(position==1) 
      frag=new SecondFragment(); 
     if(position==2) 
      frag=new ThirdFragment(); 

     return frag; 
      }

来源

2014-02-16 11:41:55

无法访问的代码。 –

@DoctororDrive ^是对的......因为我们正在返回一些东西，因此反正会这样工作......？ – user2405469

我承认我的错误，并对此非常抱歉..... –

FragmentActivity没有显示片段的正确布局

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