如何使用導航抽屜打開新活動？

Question

我想創建一個通過從左向右滑動打開的導航抽屜菜單，並且我通過Google開發者教程來完成，但本教程展示瞭如何創建導航抽屜以及如何設置菜單中的項以打開新的片段佈局，但它不是我想要的......我想要的是使用導航抽屜菜單中的項目打開新活動，而且我也這樣做了，但是當Sliding.java活動必須打開時，我的應用崩潰了。 .java是包含菜單代碼的活動。

Sliding.java：

package com.orar.cngcnasaud; 

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


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

    private CharSequence mDrawerTitle; 
    private CharSequence mTitle; 
    private String[] mPlanetTitles; 

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

     mTitle = mDrawerTitle = getTitle(); 
     mPlanetTitles = getResources().getStringArray(R.array.planets_array); 
     mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
     mDrawerList = (ListView) findViewById(R.id.left_drawer); 

     // set a custom shadow that overlays the main content when the drawer opens 
     mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); 
     // set up the drawer's list view with items and click listener 
     mDrawerList.setAdapter(new ArrayAdapter<String>(this, 
       R.layout.drawer_list_item, mPlanetTitles)); 
     mDrawerList.setOnItemClickListener(new DrawerItemClickListener()); 

     // enable ActionBar app icon to behave as action to toggle nav drawer 
     getActionBar().setDisplayHomeAsUpEnabled(true); 
     getActionBar().setHomeButtonEnabled(true); 

     // ActionBarDrawerToggle ties together the the proper interactions 
     // between the sliding drawer and the action bar app icon 
     mDrawerToggle = new ActionBarDrawerToggle(
       this,     /* host Activity */ 
       mDrawerLayout,   /* DrawerLayout object */ 
       R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */ 
       R.string.drawer_open, /* "open drawer" description for accessibility */ 
       R.string.drawer_close /* "close drawer" description for accessibility */ 
       ) { 
      public void onDrawerClosed(View view) { 
       getActionBar().setTitle(mTitle); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 

      public void onDrawerOpened(View drawerView) { 
       getActionBar().setTitle(mDrawerTitle); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 
     }; 
     mDrawerLayout.setDrawerListener(mDrawerToggle); 

     if (savedInstanceState == null) { 
      selectItem(0); 
     } 
    } 

    private void selectItem(int i) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     MenuInflater inflater = getMenuInflater(); 
     inflater.inflate(R.menu.main, menu); 
     return super.onCreateOptionsMenu(menu); 
    } 

    /* Called whenever we call invalidateOptionsMenu() */ 


    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 

     if (mDrawerToggle.onOptionsItemSelected(item)) { 
      return true; 
     } 
     return false; 


     } 



     private class DrawerItemClickListener implements ListView.OnItemClickListener { 

     @Override 
     public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, 
       long arg3) { 
      // TODO Auto-generated method stub 

     } 

    } 




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



    @Override 
    protected void onPostCreate(Bundle savedInstanceState) { 
     super.onPostCreate(savedInstanceState); 

     mDrawerToggle.syncState(); 
    } 

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

     mDrawerToggle.onConfigurationChanged(newConfig); 
    } 

     @SuppressWarnings("unused") 
     private void selectItem1(final int position) { 
      switch(position) { 
      case 1: 
        Intent a = new Intent(this, MainActivity.class); 
        startActivity(a); 
      break; 
      case 2: 
        Intent b = new Intent(this, Profesori.class); 
        startActivity(b); 
        break; 
      default: 
      } 
     } 
} 

我沒有錯誤，當我運行它，但它仍然崩潰..

編輯：

的logcat：

02-17 16:29:58.496: I/dalvikvm(322): Could not find method com.orar.cngcnasaud.Sliding.getActionBar, referenced from method com.orar.cngcnasaud.Sliding.onCreate 
02-17 16:29:58.496: W/dalvikvm(322): VFY: unable to resolve virtual method 5311: Lcom/orar/cngcnasaud/Sliding;.getActionBar()Landroid/app/ActionBar; 
02-17 16:29:58.496: D/dalvikvm(322): VFY: replacing opcode 0x6e at 0x0058 
02-17 16:29:58.496: D/dalvikvm(322): VFY: dead code 0x005b-0087 in Lcom/orar/cngcnasaud/Sliding;.onCreate (Landroid/os/Bundle;)V 
02-17 16:29:58.504: I/dalvikvm(322): Could not find method com.orar.cngcnasaud.Sliding.getActionBar, referenced from method com.orar.cngcnasaud.Sliding.setTitle 
02-17 16:29:58.504: W/dalvikvm(322): VFY: unable to resolve virtual method 5311: Lcom/orar/cngcnasaud/Sliding;.getActionBar()Landroid/app/ActionBar; 
02-17 16:29:58.504: D/dalvikvm(322): VFY: replacing opcode 0x6e at 0x0002 
02-17 16:29:58.504: D/dalvikvm(322): VFY: dead code 0x0005-000b in Lcom/orar/cngcnasaud/Sliding;.setTitle (Ljava/lang/CharSequence;)V 
02-17 16:29:58.534: D/AndroidRuntime(322): Shutting down VM 
02-17 16:29:58.534: W/dalvikvm(322): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
02-17 16:29:58.554: E/AndroidRuntime(322): FATAL EXCEPTION: main 
02-17 16:29:58.554: E/AndroidRuntime(322): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.orar.cngcnasaud/com.orar.cngcnasaud.Sliding}: java.lang.NullPointerException 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.os.Looper.loop(Looper.java:123) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread.main(ActivityThread.java:4627) 
02-17 16:29:58.554: E/AndroidRuntime(322): at java.lang.reflect.Method.invokeNative(Native Method) 
02-17 16:29:58.554: E/AndroidRuntime(322): at java.lang.reflect.Method.invoke(Method.java:521) 
02-17 16:29:58.554: E/AndroidRuntime(322): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
02-17 16:29:58.554: E/AndroidRuntime(322): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
02-17 16:29:58.554: E/AndroidRuntime(322): at dalvik.system.NativeStart.main(Native Method) 
02-17 16:29:58.554: E/AndroidRuntime(322): Caused by: java.lang.NullPointerException 
02-17 16:29:58.554: E/AndroidRuntime(322): at com.orar.cngcnasaud.Sliding.onCreate(Sliding.java:39) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
02-17 16:29:58.554: E/AndroidRuntime(322): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
02-17 16:29:58.554: E/AndroidRuntime(322): ... 11 more 
02-17 16:30:06.275: I/Process(322): Sending signal. PID: 322 SIG: 9 

滑動.xml：

<android.support.v4.widget.DrawerLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/drawer_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@drawable/bff"> 

    <!-- As the main content view, the view below consumes the entire 
     space available using match_parent in both dimensions. --> 
    <FrameLayout 
     android:id="@+id/content_frame" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" /> 


    <ListView 
     android:id="@+id/left_drawer" 
     android:layout_width="240dp" 
     android:layout_height="match_parent" 
     android:layout_gravity="start" 
     android:choiceMode="singleChoice" 
     android:divider="@android:color/transparent" 
     android:dividerHeight="0dp" 
     android:background="#111"/> 
</android.support.v4.widget.DrawerLayout> 

Answer 1

您在這裏有一個空指針：

Caused by: java.lang.NullPointerException at com.orar.cngcnasaud.Sliding.onCreate(Sliding.java:39) 

這似乎是你DrawerLayout（不知道的行反正）：

mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); 

您能查看/發表您的佈局？

Answer 2

我有同樣的問題。所以我使用以下步驟解決它。這對別人很有用。

問題是因爲編譯器在activity_main.xml中搜索drawer_layout。

setContentView(R.layout.activity_main); 
//You added the view file as activity_main 

mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
//While execution the compiler will search "drawer_layout" in the view file (activity_main.xml). But the drawer_layout is in sliding.xml. 

但沒有"drawer_layout"在activity_main.xml增加。它添加在"sliding.xml"

所以，要解決這個問題，我們需要在activity_main.xml中添加以下內容。

<android.support.v4.widget.DrawerLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/drawer_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@drawable/bff"> 

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


    <ListView 
     android:id="@+id/left_drawer" 
     android:layout_width="240dp" 
     android:layout_height="match_parent" 
     android:layout_gravity="start" 
     android:choiceMode="singleChoice" 
     android:divider="@android:color/transparent" 
     android:dividerHeight="0dp" 
     android:background="#111"/> 

<!-- The content in the activity_main.xml --> 

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