不明白导航抽屉图标显示两次的原因

Question

我不确定为什么我的代码会导致图标在我的应用程序中出现两次。有人可以看看，告诉我哪条线正在做，也许是如何解决它？对于Android来说，我对这类事情还有点新意。

代码：

info.androidhive.slidingmenu;

import android.os.Bundle;
import android.app.Activity; 
import android.content.res.Configuration;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.view.MenuItem;
import android.view.View; 
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

private String[] drawerListViewItems;
private DrawerLayout drawerLayout;
private ListView drawerListView;
private ActionBarDrawerToggle actionBarDrawerToggle;

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

    // get list items from strings.xml
    drawerListViewItems = getResources().getStringArray(R.array.items);
    // get ListView defined in activity_main.xml
    drawerListView = (ListView) findViewById(R.id.left_drawer);

    // Set the adapter for the list view
    drawerListView.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_listview_item, drawerListViewItems));

    // 2. App Icon 
    drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

    // 2.1 create ActionBarDrawerToggle
    actionBarDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            drawerLayout,         /* DrawerLayout object */
            R.raw.ic_drawer,  /* nav drawer icon to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description */
            R.string.drawer_close  /* "close drawer" description */
            );

    // 2.2 Set actionBarDrawerToggle as the DrawerListener
    drawerLayout.setDrawerListener(actionBarDrawerToggle);

    // 2.3 enable and show "up" arrow
    getActionBar().setDisplayHomeAsUpEnabled(true); 

    drawerListView.setOnItemClickListener(new DrawerItemClickListener());
}

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
     actionBarDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    actionBarDrawerToggle.onConfigurationChanged(newConfig);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

     // call ActionBarDrawerToggle.onOptionsItemSelected(), if it returns true
    // then it has handled the app icon touch event

    if (actionBarDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

private class DrawerItemClickListener implements ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        Toast.makeText(MainActivity.this, ((TextView)view).getText(), Toast.LENGTH_LONG).show();
        drawerLayout.closeDrawer(drawerListView);

    }
}
}

Answer 1

package info.androidhive.slidingmenu;

import android.os.Bundle;
import android.app.Activity;
import android.content.res.Configuration;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

private String[] drawerListViewItems;
private DrawerLayout drawerLayout;
private ListView drawerListView;
private ActionBarDrawerToggle actionBarDrawerToggle;

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

    // get list items from strings.xml
    drawerListViewItems = getResources().getStringArray(R.array.items);
    // get ListView defined in activity_main.xml
    drawerListView = (ListView) findViewById(R.id.left_drawer);

    // Set the adapter for the list view
    drawerListView.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_listview_item, drawerListViewItems));

    // 2. App Icon 
    drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

    // 2.1 create ActionBarDrawerToggle
    actionBarDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            drawerLayout,         /* DrawerLayout object */
            R.drawable.ic_drawer,  /* nav drawer icon to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description */
            R.string.drawer_close  /* "close drawer" description */
            );

    // 2.2 Set actionBarDrawerToggle as the DrawerListener
    drawerLayout.setDrawerListener(actionBarDrawerToggle);

    // 2.3 enable and show "up" arrow
    getActionBar().setDisplayHomeAsUpEnabled(true); 

    // just styling option
    drawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); 
    //this is the line of code i needed. and also download the icon package for the shadow

    drawerListView.setOnItemClickListener(new DrawerItemClickListener());
}

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
     actionBarDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    actionBarDrawerToggle.onConfigurationChanged(newConfig);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

     // call ActionBarDrawerToggle.onOptionsItemSelected(), if it returns true
    // then it has handled the app icon touch event

    if (actionBarDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

private class DrawerItemClickListener implements ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView parent, View view, int position, long id) {
        Toast.makeText(MainActivity.this, ((TextView)view).getText(), Toast.LENGTH_LONG).show();
        drawerLayout.closeDrawer(drawerListView);

    }
}

}