blocks|key|394207|text|在您的AndroidManifest.xml添加|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|394208|<application+android:name="YOURPACKAGENAME.AppController"+
+++++++++++++android:allowbackup="true"+
+++++++++++++android:icon="@drawable/ic_launcher"+
+++++++++++++android:label="@string/app_name"
+++++++++++++android:theme="@style/AppTheme">|code-block|syntax|javascript|394209|entityMap^0|3|J|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

In your <code>AndroidManifest.xml</code> add

<pre><code>&lt;application android:name="YOURPACKAGENAME.AppController" 
 android:allowbackup="true" 
 android:icon="@drawable/ic_launcher" 
 android:label="@string/app_name"
 android:theme="@style/AppTheme"&gt;
</code></pre>

blocks|key|418691|text|正如N1to所说，您需要在AndroidManifest.xml中添加控制器，如果不添加控制器，则永远不会调用onCreate()，调用AppController.getInstance()时实例为null。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|418692|<application+android:name="YOURPACKAGENAME.AppController"+
+++++++++android:allowbackup="true"+
+++++++++android:icon="@drawable/ic_launcher"+
+++++++++android:label="@string/app_name"
+++++++++android:theme="@style/AppTheme">|code-block|syntax|javascript|418693|它也适用于我，因为：|418694|<application+android:name=".AppController"+
+++++++++android:allowbackup="true"+
+++++++++android:icon="@drawable/ic_launcher"+
+++++++++android:label="@string/app_name"
+++++++++android:theme="@style/AppTheme">|418695|entityMap^0|D|J|1J|A|1W|R|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

As N1to says, you need to add your controller in the <code>AndroidManifest.xml</code>, if you don't add it then the <code>onCreate()</code> is never called and when you call <code>AppController.getInstance()</code> the instance is null.

<pre><code>&lt;application android:name="YOURPACKAGENAME.AppController" 
 android:allowbackup="true" 
 android:icon="@drawable/ic_launcher" 
 android:label="@string/app_name"
 android:theme="@style/AppTheme"&gt;
</code></pre>

It also works for me with:

<pre><code>&lt;application android:name=".AppController" 
 android:allowbackup="true" 
 android:icon="@drawable/ic_launcher" 
 android:label="@string/app_name"
 android:theme="@style/AppTheme"&gt;
</code></pre>

blocks|key|1574930|text|在我的例子中，我忘记初始化变量rq，请确保您做到了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1574931|++++...
++++private+RequestQueue+rq;+++//+rq+=+null+(NullPointerException+if+you+use+it)
++++...

++++@Override
++++protected+void+onCreate(Bundle+savedInstanceState)+{
++++++++super.onCreate(savedInstanceState);
++++++++...
++++++++rq+=+Volley.newRequestQueue(YourActivity.this);++//+rq+!=+null
++++}
++++...
++++rq.add(request);|code-block|syntax|javascript|1574932|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In my case, I forgot to initialize the variable rq, please, make sure you did it

<pre><code> ...
 private RequestQueue rq; // rq = null (NullPointerException if you use it)
 ...

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 ...
 rq = Volley.newRequestQueue(YourActivity.this); // rq != null
 }
 ...
 rq.add(request);
</code></pre>

blocks|key|1574947|text|您没有将任何数据传递给volley方法，这意味着它将获得空数据(空数据)……见示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1574948|protected+Map<String,+String>+getParams()+throws+AuthFailureError+{
++++++++++++++++Map<String,+String>+map=new+HashMap<>();
++++++++++++++++map.put(region,+regionName);
++++++++++++++++return+map;
++++++++++++}|code-block|syntax|javascript|1574949|如果regionName是空的，它会给你NullPointerException，所以regionName一定有东西……|1574950|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You didn't pass any data to the volley method, that means it get null data (empty data).....
see example:

<pre><code>protected Map&lt;String, String&gt; getParams() throws AuthFailureError {
 Map&lt;String, String&gt; map=new HashMap&lt;&gt;();
 map.put(region, regionName);
 return map;
 }
</code></pre>

if regionName is empty it will give you NullPointerException, so regionName must have something.....

blocks|key|394239|text|在menifest文件中添加appcontroller，如下所示|type|unstyled|depth|inlineStyleRanges|entityRanges|data|394240|<application+android:name="app.AppController"+
+++++++++android:allowbackup="true"+
+++++++++android:icon="@drawable/ic_launcher"+
+++++++++android:label="@string/app_name"
+++++++++android:theme="@style/AppTheme">|code-block|syntax|javascript|394241|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In menifest file add appcontroller as shown

<pre><code>&lt;application android:name="app.AppController" 
 android:allowbackup="true" 
 android:icon="@drawable/ic_launcher" 
 android:label="@string/app_name"
 android:theme="@style/AppTheme"&gt;
</code></pre>

blocks|key|418764|text|请检查是否已将requestQueue对象初始化为：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|418765|requestQueue+=+Volley.newRequestQueue(this);|code-block|syntax|javascript|418766|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Please check if you've initialized your requestQueue object as :

<pre><code>requestQueue = Volley.newRequestQueue(this);

</code></pre>

blocks|key|1574983|text|在onCreate()中尝试以下操作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1574984|requestQueue=Volley.newRequestQueue(getApplicationContext());|code-block|syntax|javascript|1574985|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

try this inside onCreate()
<pre><code>requestQueue=Volley.newRequestQueue(getApplicationContext());
</code></pre>

blocks|key|1575013|text|我也有同样的错误，因为我在方法中错误地引用了xml文件。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1575014|//+R.layout.activity_calender应该是活动的同一个xml文件(CalenderActivity)|1575015|setContentView(R.layout.activity_calender);|CODE|1575016|entityMap^0|D|E|0|0|0|17|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|P|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|Q|8|@$9|R|A|S|B|J]]|D|@]|E|$]]|$1|K|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|L|$]]

I have the same error because i have mistakenly referenced the wrong xml file in <code>onCreate</code> method
// R.layout.activity_calender should be the same xml file of your activity (CalenderActivity) 
<code>setContentView(R.layout.activity_calender);</code>

I'm using <a href="http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/" rel="noreferrer">AndroidHive register login</a> and it's working fine in example project of this login-register.

But after many attempts trying it with <code>CardView</code>s and other widgets, this error appears on the <code>LogCat</code>:

<pre><code>java.lang.NullPointerException: Attempt to invoke virtual method 'void client.myproject.app.AppController.addToRequestQueue(com.android.volley.Request, java.lang.String)' on a null object reference
 at client.myproject.RegisterActivity.registerUser(RegisterActivity.java:185)
 at client.myproject.RegisterActivity.access$300(RegisterActivity.java:35)
 at client.myproject.RegisterActivity$1.onClick(RegisterActivity.java:81)
 at android.view.View.performClick(View.java:4780)
 at android.view.View$PerformClick.run(View.java:19866)
 at android.os.Handler.handleCallback(Handler.java:739)
 at android.os.Handler.dispatchMessage(Handler.java:95)
 at android.os.Looper.loop(Looper.java:135)
 at android.app.ActivityThread.main(ActivityThread.java:5254)
 at java.lang.reflect.Method.invoke(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:372)
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
</code></pre>

While these codes works fine in a single app (just with register login).

I'm using Volley library.

NullPointerException addToRequestQueue(com.android.volley.Request, java.lang.String)' on a null object reference

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在使用，它在这个登录注册的示例项目中运行得很好。但是，在多次尝试使用CardView和其他小部件时，这个错误会出现在LogCat上。java.lang.NullPointerException: Attempt to invoke virtual method 'void client.myproject.app....

问空对象引用上的NullPointerException addToRequestQueue(com.android.volley.Request，java.lang.String)‘
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问空对象引用上的NullPointerException addToRequestQueue(com.android.volley.Request，java.lang.String)‘EN