Java 如何访问ViewPager'；是否已选择NavigationDrawerItems中的s实例？

我是JAVA和Android编程的初学者。以下是我对应用程序结构的概念

↑→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→↓

导航抽屉------------------------------------------主页-----------------详细信息

（所有ViewPager实例的左幻灯片）-（ViewPager实例1）---（ViewPager实例2）

我使用Eclipse创建代码，但问题是我无法将NavicationDrawer的片段连接到详细页面。它连接到作为原始源的主页

这是我的密码

MainActivity.java

package com.example.ex_tabb;

import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;

@SuppressWarnings("deprecation")
public class MainActivity extends ActionBarActivity implements Main_NavigationDrawerFragment.NavigationDrawerCallbacks {

    Main_PagerAdapter mSectionsPagerAdapter;
    ViewPager mViewPager;
    ImageView homebtn;
    private Main_NavigationDrawerFragment mNavigationDrawerFragment;
    private Fragment fragment;

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

        mSectionsPagerAdapter = new Main_PagerAdapter(getSupportFragmentManager());

        mViewPager = (ViewPager) findViewById(R.id.pager);
        homebtn = (ImageView) findViewById(R.id.btn_home);

        mViewPager.setAdapter(mSectionsPagerAdapter);

        mNavigationDrawerFragment = (Main_NavigationDrawerFragment) getSupportFragmentManager()
                .findFragmentById(R.id.navigation_drawer);

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(R.id.navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout));

        homebtnOnClicklistener();

        Button tempbt = (Button) findViewById(R.id.button1);
        tempbt.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                switch (mViewPager.getCurrentItem()) {
                case 0:
                    mViewPager.setCurrentItem(1);
                    break;
                case 1:
                    mViewPager.setCurrentItem(2);
                    break;
                case 2:
                    mViewPager.setCurrentItem(3);
                    break;

                default:
                    break;
                }
            }
        });
    }

    private void homebtnOnClicklistener() {
        // TODO Auto-generated method stub

        homebtn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                mViewPager.setCurrentItem(0);
            }
        });
    }

    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        switch (position) {
        default:
        case 0:
            fragment = new PlaceholderFragment();
            break;
        case 1:
            fragment = new PlaceholderFragment2();
            break;
        case 2:
            fragment = new PlaceholderFragment2();
            break;

        }
        fragmentManager.beginTransaction().add(R.id.container, fragment).commit();
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */

        /**
         * 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();
            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, container, false);
            return rootView;
        }

    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment2 extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */

        /**
         * Returns a new instance of this fragment for the given section number.
         */
        public static PlaceholderFragment2 newInstance(int sectionNumber) {
            PlaceholderFragment2 fragment = new PlaceholderFragment2();
            Bundle args = new Bundle();
            fragment.setArguments(args);
            return fragment;
        }

        public PlaceholderFragment2() {
        }

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

    }
}

Main_NavigationDrawerFragment.java

package com.example.ex_tabb;

import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Main_NavigationDrawerFragment extends Fragment {

    private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";

    /**
     * A pointer to the current callbacks instance (the Activity).
     */
    private NavigationDrawerCallbacks mCallbacks;

    /**
     * Helper component that ties the action bar to the navigation drawer.
     */

    private DrawerLayout mDrawerLayout;
    private ListView mDrawerListView;
    private View mFragmentContainerView;

    private int mCurrentSelectedPosition = 0;
    private boolean mFromSavedInstanceState;
    private boolean mUserLearnedDrawer;

    public Main_NavigationDrawerFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Read in the flag indicating whether or not the user has demonstrated
        // awareness of the
        // drawer. See PREF_USER_LEARNED_DRAWER for details.
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
        mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);

        // Select either the default item (0) or the last selected item.
        selectItem(mCurrentSelectedPosition);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        // Indicate that this fragment would like to influence the set of
        // actions in the action bar.
        setHasOptionsMenu(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        mDrawerListView = (ListView) inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });
        mDrawerListView.setAdapter(
                new ArrayAdapter<String>(getActivity().getBaseContext(), android.R.layout.simple_list_item_activated_1,
                        android.R.id.text1, new String[] { getString(R.string.title_section1),
                                getString(R.string.title_section2), getString(R.string.title_section3), }));
        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return mDrawerListView;
    }

    public boolean isDrawerOpen() {
        return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
    }

    public void setUp(int fragmentId, DrawerLayout drawerLayout) {
        mFragmentContainerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
        if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
            mDrawerLayout.openDrawer(mFragmentContainerView);
        }

    }

    private void selectItem(int position) {
        mCurrentSelectedPosition = position;
        if (mDrawerListView != null) {
            mDrawerListView.setItemChecked(position, true);
        }
        if (mDrawerLayout != null) {
            mDrawerLayout.closeDrawer(mFragmentContainerView);
        }
        if (mCallbacks != null) {
            mCallbacks.onNavigationDrawerItemSelected(position);
        }
    }

    @SuppressWarnings("deprecation")
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallbacks = (NavigationDrawerCallbacks) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mCallbacks = null;
    }

    public static interface NavigationDrawerCallbacks {
        /**
         * Called when an item in the navigation drawer is selected.
         */
        void onNavigationDrawerItemSelected(int position);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        tools:context="com.example.ex_tabb.MainActivity$PlaceholderFragment" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical" >

            <RelativeLayout
                style="@style/global_header"
                android:layout_width="match_parent" >

                <ImageButton
                    android:id="@+id/btn_home"
                    style="@style/global_header_button"
                    android:layout_centerInParent="true"
                    android:contentDescription="@string/__empty"
                    android:src="@drawable/selector_header_bt_home" />
            </RelativeLayout>

            <Button
                android:id="@+id/button1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Button" />

            <com.example.ex_tabb.Main_ViewPager
                android:id="@+id/pager"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                tools:context="com.example.ex_tabb.MainActivity" >

                <FrameLayout
                    android:id="@+id/container"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" >

                </FrameLayout>
            </com.example.ex_tabb.Main_ViewPager>
        </LinearLayout>
    </RelativeLayout>

    <fragment
        android:id="@+id/navigation_drawer"
        android:name="com.example.ex_tabb.Main_NavigationDrawerFragment"
        android:layout_width="@dimen/navigation_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

---

这里有进展。我不确定一切都好

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    mDrawerListView = (ListView) inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
    mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            **com.example.ex_tabb.MainActivity.mViewPager.setCurrentItem(1);
            selectItem(position);**
        }
    });

    mDrawerListView.setAdapter(
            new ArrayAdapter<String>(getActivity().getBaseContext(), android.R.layout.simple_list_item_activated_1,
                    android.R.id.text1, new String[] { getString(R.string.title_section1),
                            getString(R.string.title_section2), getString(R.string.title_section3), }));
    mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
    return mDrawerListView;
}

@覆盖
CreateView上的公共视图（布局、充气机、视图组容器、捆绑包保存状态）{
mDrawerListView=（ListView）充气器。充气（R.layout.fragment\u导航\u抽屉，容器，false）；
mDrawerListView.setOnItemClickListener（新的AdapterView.OnItemClickListener（）{
@凌驾
public void onItemClick（AdapterView父对象、视图、整型位置、长id）{
**com.example.ex_tabb.MainActivity.mViewPager.setCurrentItem（1）；
选择项目（位置）**
}
});
mDrawerListView.setAdapter(
新的ArrayAdapter（getActivity（）.getBaseContext（），android.R.layout.simple\u list\u item\u activated\u 1，
android.R.id.text1，新字符串[]{getString（R.String.title_section1），
getString（R.string.title_section2），getString（R.string.title_section3），}）；
mDrawerListView.setItemChecked（mCurrentSelectedPosition，true）；
返回mDrawerListView；
}

我找到了答案。但还是继续。。。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    mDrawerListView = (ListView) inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
    mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            **com.example.ex_tabb.MainActivity.mViewPager.setCurrentItem(1);
            selectItem(position);**
        }
    });

    mDrawerListView.setAdapter(
            new ArrayAdapter<String>(getActivity().getBaseContext(), android.R.layout.simple_list_item_activated_1,
                    android.R.id.text1, new String[] { getString(R.string.title_section1),
                            getString(R.string.title_section2), getString(R.string.title_section3), }));
    mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
    return mDrawerListView;
}