Java 显示相同内容的Android Studio选项卡式活动

我用viewpager创建了一个新的android studio选项卡式活动，但这三个选项卡是相同的，我在这里的片段中放的内容是我的类

package com.mrad4tech.development.tabbedactivity;
import java.util.Locale;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.FragmentPagerAdapter;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class MainActivity2Activity extends ActionBarActivity implements ActionBar.TabListener {

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link FragmentPagerAdapter} derivative, which will keep every
 * loaded fragment in memory. If this becomes too memory intensive, it
 * may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_activity2);

    // Set up the action bar.
    final ActionBar actionBar = getSupportActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    // When swiping between different sections, select the corresponding
    // tab. We can also use ActionBar.Tab#select() to do this if we have
    // a reference to the Tab.
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }
    });

    // For each of the sections in the app, add a tab to the action bar.
    for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
        // Create a tab with text corresponding to the page title defined by
        // the adapter. Also specify this Activity object, which implements
        // the TabListener interface, as the callback (listener) for when
        // this tab is selected.
        actionBar.addTab(
                actionBar.newTab()
                        .setText(mSectionsPagerAdapter.getPageTitle(i))
                        .setTabListener(this));
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main_activity2, 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();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, switch to the corresponding page in
    // the ViewPager.
    mViewPager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        // Return a PlaceholderFragment (defined as a static inner class below).
        return PlaceholderFragment.newInstance(position + 1);
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            case 2:
                return getString(R.string.title_section3).toUpperCase(l);
        }
        return null;
    }
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static PlaceholderFragment newInstance(int sectionNumber) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main_activity2, container, false);
        return rootView;
    }
}

 }

package com.mrad4tech.development.tabbedactivity；
导入java.util.Locale；
导入android.support.v7.app.ActionBarActivity；
导入android.support.v7.app.ActionBar；
导入android.support.v4.app.Fragment；
导入android.support.v4.app.FragmentManager；
导入android.support.v4.app.FragmentTransaction；
导入android.support.v4.app.FragmentPagerAdapter；
导入android.os.Bundle；
导入android.support.v4.view.ViewPager；
导入android.view.Gravity；
导入android.view.LayoutInflater；
导入android.view.Menu；
导入android.view.MenuItem；
导入android.view.view；
导入android.view.ViewGroup；
导入android.widget.TextView；
公共类MainActivity2Activity扩展ActionBarActivity实现ActionBar.TabListener{
/**
*将提供的{@link android.support.v4.view.PagerAdapter}
*每个部分的片段。我们使用
*{@link FragmentPagerAdapter}派生，它将保留
*已在内存中加载片段。如果这变得过于内存密集，则
*最好是换成一个
*{@link android.support.v4.app.FragmentStatePagerAdapter}。
*/
分段SPAGERADAPTER mSectionsPagerAdapter；
/**
*将承载节内容的{@link ViewPager}。
*/
ViewPager mViewPager；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity\u main\u activity2）；
//设置操作栏。
最终ActionBar ActionBar=getSupportActionBar（）；
actionBar.setNavigationMode（actionBar.NAVIGATION\u MODE\u选项卡）；
//创建适配器，该适配器将为这三个函数中的每一个返回一个片段
//活动的主要部分。
mSectionsPagerAdapter=newsectionspageradapter（getSupportFragmentManager（））；
//使用分区适配器设置ViewPager。
mViewPager=（ViewPager）findViewById（R.id.pager）；
mViewPager.setAdapter（mSectionsPagerAdapter）；
//在不同区段之间滑动时，选择相应的
//我们也可以使用ActionBar.tab#select（）来完成这项工作
//对选项卡的引用。
mViewPager.setOnPageChangeListener（新的ViewPager.SimpleOnPageChangeListener（）{
@凌驾
已选择页面上的公共无效（内部位置）{
actionBar.setSelectedNavigationItem（位置）；
}
});
//对于应用程序中的每个部分，在操作栏中添加一个选项卡。
对于（int i=0；ipublic static class PlaceholderFragment extends Fragment {

  private static final String ARG_SECTION_NUMBER = "section_number";

  // A field that contains your args value;
  private int mSectionNumber;

  public static PlaceholderFragment newInstance(int sectionNumber) {
    PlaceholderFragment fragment = new PlaceholderFragment();
    Bundle args = new Bundle();
    args.putInt(ARG_SECTION_NUMBER, sectionNumber);
    fragment.setArguments(args);
    return fragment;
  }

  public PlaceholderFragment() {
  }

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Parses your arguments
    if(getArguments() != null) {
      mSectionNumber = getArguments().getInt(ARG_SECTION_NUMBER);
    }
  }

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                           Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main_activity2, container, false);
    return rootView;
  }

  @Override
  public void onViewCreated(View view, Bundle savedInstanceState) {
    // Updates your view
    ((TextView) findViewById(R.id.text1)).setText("Section Number: " + mSectionNumber);
  }
}

@Override
public Fragment getItem(int position) {
    // getItem is called to instantiate the fragment for the given page.
    switch (position) {
        case 0:
            return FragmentFirst.newInstance();
        case 1:
            return FragmentSecond.newInstance();
        case 2:
            return FragmentThird.newInstance();
        default:
            //assume you only have 3
            throw new IllegalArgumentException();
    }
}

public static class FragmentFirst extends Fragment {
    public static FragmentFirst newInstance(int sectionNumber) {
        FragmentFirst fragment = new FragmentFirst();
        return fragment;
    }

    public FragmentFirst() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_first, container, false);
        return rootView;
    }
}

public static class FragmentSecond extends Fragment {
    public static FragmentSecond newInstance(int sectionNumber) {
        FragmentSecond fragment = new FragmentSecond();
        return fragment;
    }

    public FragmentSecond() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_second, container, false);
        return rootView;
    }
}

public static class FragmentThird extends Fragment {
    public static FragmentThird newInstance(int sectionNumber) {
        FragmentThird fragment = new FragmentThird();
        return fragment;
    }

    public FragmentThird() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_third, container, false);
        return rootView;
    }
}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        switch (position) {
        case 0:
            return FragmentFirst.newInstance();
        case 1:
            return FragmentSecond.newInstance();
        case 2:
            return FragmentThird.newInstance();
        default:
            //assume you only have 3
            throw new IllegalArgumentException();
        }
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            case 2:
                return getString(R.string.title_section3).toUpperCase(l);
        }
        return null;
    }
}