Android - 片段中的後退按鈕導航

Question

大家好我創建了一個用於學習目的的簡單應用程序。我已經在應用程序的片段1中放置了一個按鈕，一旦按鈕被觸發，它就會導航到片段2.我希望能夠使用操作欄後退按鈕回到片段1，如第二張圖片所示。我嘗試過不同的方法來解決它，但我似乎無法做到。

所以，如果有人能告訴我如何從片段2返回到片段1，這將是驚人的。提前致謝。

這是我現在的代碼。

圖片1 圖片2

MainActivity：

package info.androidhive.slidingmenu; 

import info.androidhive.slidingmenu.adapter.NavDrawerListAdapter; 
import info.androidhive.slidingmenu.model.NavDrawerItem; 

import java.util.ArrayList; 

import android.annotation.SuppressLint; 
import android.app.Activity; 
import android.app.Fragment; 
import android.app.FragmentManager; 
import android.content.res.Configuration; 
import android.content.res.TypedArray; 
import android.os.Bundle; 
import android.support.v4.app.ActionBarDrawerToggle; 
import android.support.v4.widget.DrawerLayout; 
import android.util.Log; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.ListView; 

public class MainActivity extends Activity { 
    private DrawerLayout mDrawerLayout; 
    private ListView mDrawerList; 
    private ActionBarDrawerToggle mDrawerToggle; 

    // nav drawer title 
    private CharSequence mDrawerTitle; 

    // used to store app title 
    private CharSequence mTitle; 

    // slide menu items 
    private String[] navMenuTitles; 
    private TypedArray navMenuIcons; 

    private ArrayList<NavDrawerItem> navDrawerItems; 
    private NavDrawerListAdapter adapter; 

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

     mTitle = mDrawerTitle = getTitle(); 

     // load slide menu items 
     navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items); 

     // nav drawer icons from resources 
     navMenuIcons = getResources() 
       .obtainTypedArray(R.array.nav_drawer_icons); 

     mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
     mDrawerList = (ListView) findViewById(R.id.list_slidermenu); 

     navDrawerItems = new ArrayList<NavDrawerItem>(); 

     // adding nav drawer items to array 
     // Home 
     navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1))); 



     // Recycle the typed array 
     navMenuIcons.recycle(); 

     mDrawerList.setOnItemClickListener(new SlideMenuClickListener()); 

     // setting the nav drawer list adapter 
     adapter = new NavDrawerListAdapter(getApplicationContext(), 
       navDrawerItems); 
     mDrawerList.setAdapter(adapter); 

     // enabling action bar app icon and behaving it as toggle button 
     getActionBar().setDisplayHomeAsUpEnabled(true); 
     getActionBar().setHomeButtonEnabled(true); 

     mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, 
       R.drawable.ic_drawer, //nav menu toggle icon 
       R.string.app_name, // nav drawer open - description for accessibility 
       R.string.app_name // nav drawer close - description for accessibility 
     ) { 
      public void onDrawerClosed(View view) { 
       getActionBar().setTitle(mTitle); 
       // calling onPrepareOptionsMenu() to show action bar icons 
       invalidateOptionsMenu(); 
      } 

      public void onDrawerOpened(View drawerView) { 
       getActionBar().setTitle(mDrawerTitle); 
       // calling onPrepareOptionsMenu() to hide action bar icons 
       invalidateOptionsMenu(); 
      } 
     }; 
     mDrawerLayout.setDrawerListener(mDrawerToggle); 

     if (savedInstanceState == null) { 
      // on first time display view for first nav item 
      displayView(0); 
     } 
    } 

    /** 
    * Slide menu item click listener 
    * */ 
    private class SlideMenuClickListener implements 
      ListView.OnItemClickListener { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, 
       long id) { 
      // display view for selected nav drawer item 
      displayView(position); 
     } 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // toggle nav drawer on selecting action bar app icon/title 
     if (mDrawerToggle.onOptionsItemSelected(item)) { 
      return true; 
     } 
     // Handle action bar actions click 
     switch (item.getItemId()) { 
     case R.id.action_settings: 
      return true; 
     default: 
      return super.onOptionsItemSelected(item); 
     } 
    } 

    /* * 
    * Called when invalidateOptionsMenu() is triggered 
    */ 
    @Override 
    public boolean onPrepareOptionsMenu(Menu menu) { 
     // if nav drawer is opened, hide the action items 
     boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList); 
     menu.findItem(R.id.action_settings).setVisible(!drawerOpen); 
     return super.onPrepareOptionsMenu(menu); 
    } 

    /** 
    * Diplaying fragment view for selected nav drawer list item 
    * */ 
    private void displayView(int position) { 
     // update the main content by replacing fragments 
     Fragment fragment = null; 
     switch (position) { 
     case 0: 
      fragment = new Fragment_1(); 
      break; 


     default: 
      break; 
     } 

     if (fragment != null) { 
      FragmentManager fragmentManager = getFragmentManager(); 
      fragmentManager.beginTransaction() 
        .replace(R.id.frame_container, fragment).commit(); 

      // update selected item and title, then close the drawer 
      mDrawerList.setItemChecked(position, true); 
      mDrawerList.setSelection(position); 
      setTitle(navMenuTitles[position]); 
      mDrawerLayout.closeDrawer(mDrawerList); 
     } else { 
      // error in creating fragment 
      Log.e("MainActivity", "Error in creating fragment"); 
     } 
    } 

    @Override 
    public void setTitle(CharSequence title) { 
     mTitle = title; 
     getActionBar().setTitle(mTitle); 
    } 

    /** 
    * When using the ActionBarDrawerToggle, you must call it during 
    * onPostCreate() and onConfigurationChanged()... 
    */ 

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

    @Override 
    public void onConfigurationChanged(Configuration newConfig) { 
     super.onConfigurationChanged(newConfig); 
     // Pass any configuration change to the drawer toggls 
     mDrawerToggle.onConfigurationChanged(newConfig); 
    } 

} 

Fragment_1：

package info.androidhive.slidingmenu; 

import android.app.Fragment; 
import android.app.FragmentManager; 
import android.app.FragmentTransaction; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.ViewGroup; 
import android.widget.Button; 

public class Fragment_1 extends Fragment implements OnClickListener{ 
    private Button button; 
    public Fragment_1(){} 

    @Override 

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

     View rootView = inflater.inflate(R.layout.fragment_1, container, false); 

     Button b = (Button) rootView.findViewById(R.id.button1); 
     b.setOnClickListener(this); 

     return rootView; 
    } 

    public void onClick(View v) { 

     switch (v.getId()) { 
     case R.id.button1: 

      Fragment newFragment = new Fragment_2(); 
      FragmentTransaction transaction = getFragmentManager().beginTransaction(); 

      FragmentManager fragmentManager = getFragmentManager(); 
      fragmentManager.beginTransaction() 
        .replace(R.id.frame_container, newFragment).commit(); 

      break; 
     } 
    } 


} 

Fragment_2：

package info.androidhive.slidingmenu; 

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

public class Fragment_2 extends Fragment { 

    public Fragment_2(){} 

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

     View rootView = inflater.inflate(R.layout.fragment_2, container, false); 

     return rootView; 
    } 


} 

清單：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="info.androidhive.slidingmenu" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="11" 
     android:targetSdkVersion="17" /> 

    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name="info.androidhive.slidingmenu.MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity android:name=".Fragment_2" > 
     </activity> 

    </application> 

</manifest> 

Answer 1

這不是你希望的答案，但是從設計的角度來看 - 如果抽屜式導航仍然是提供給用戶這樣做不希望將「漢堡包」改爲後退箭頭。漢堡包是導航抽屜可以訪問的用戶提示。

當第二個活動取代導航抽屜活動，並且導航抽屜不再可訪問時（即啓動設置活動後），應顯示該後退按鈕。

而且，如果仔細查看圖片2的屏幕截圖，您會看到第二個活動已啓動，而不是片段。

TL; DR - 啓動碎片時以及導航抽屜仍然可用時，不要替換漢堡包圖標。