Java 我的申请没有'；不要在活动中自行运行

我的logcat出现了一些错误，我的应用程序不能在智能手机上运行。。。 我更改了清单和MainActivity（名为HomaActivity）中的一些代码

这是我的舱单：

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="ir.homa">
<permission
    android:name="android.permission.INTERNET">
</permission>
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="24" />
    <application
        android:name=".AppController"
        android:allowBackup="true"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >



        <activity
            android:name=".HomaActivity"
            android:label="@string/app_name"
            android:launchMode="singleTop"   >
            <intent-filter >
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".LoginActivity"
            android:label="@string/app_name"
            android:launchMode="singleTop"
            android:windowSoftInputMode="adjustPan" >
            <category android:name="android.intent.category.DEFAULT" />
        </activity>
        <activity
            android:name=".RegisterActivity"
            android:label="@string/app_name"
            android:launchMode="singleTop"
            android:windowSoftInputMode="adjustPan" >

            <category android:name="android.intent.category.DEFAULT" />
        </activity><!-- ATTENTION: This was auto-generated to add Google Play services to your project for
     App Indexing.  See https://g.co/AppIndexing/AndroidStudio for more information. -->
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />


    </application>

</manifest>

我的日志中有以下错误：

   07-02 20:26:44.441 26501-26501/ir.homa E/AndroidRuntime: FATAL EXCEPTION: main
                                                         Process: ir.homa, PID: 26501
                                                         java.lang.RuntimeException: Unable to start activity ComponentInfo{ir.homa/ir.homa.HomaActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.common.api.GoogleApiClient.connect()' on a null object reference
                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2658)
                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723)
                                                             at android.app.ActivityThread.access$900(ActivityThread.java:172)
                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422)
                                                             at android.os.Handler.dispatchMessage(Handler.java:102)
                                                             at android.os.Looper.loop(Looper.java:145)
                                                             at android.app.ActivityThread.main(ActivityThread.java:5832)
                                                             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:1399)
                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
                                                          Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.common.api.GoogleApiClient.connect()' on a null object reference
                                                             at ir.homa.HomaActivity.onStart(HomaActivity.java:127)
                                                             at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1234)
                                                             at android.app.Activity.performStart(Activity.java:6258)
                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2621)
                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723) 
                                                             at android.app.ActivityThread.access$900(ActivityThread.java:172) 
                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422) 
                                                             at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                             at android.os.Looper.loop(Looper.java:145) 
                                                             at android.app.ActivityThread.main(ActivityThread.java:5832) 
                                                             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:1399) 
                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 

在

onStart（）

中，您有：

GoogleApiClient client = null;
client.connect();

客户端

为

空

。因此，如果不在

onStart（）

中获得

NullPointerException

，则无法对其调用

connect（）

，您有：

GoogleApiClient client = null;
client.connect();

---

客户端

为

空

。因此，如果不获得

NullPointerException

，这是您的问题，您正在对null变量调用一个方法：

GoogleApiClient client = null;
client.connect();

您需要首先初始化客户端。像这样的

GoogleApiClient googleApiClient = new GoogleApiClient.Builder(this)
    .enableAutoManage(this /* FragmentActivity */,
                  this /* OnConnectionFailedListener */)
    .addApi(Drive.API)
    .addScope(Drive.SCOPE_FILE)
    .build();

---

检查。

这是您的问题，您正在对空变量调用方法：

GoogleApiClient client = null;
client.connect();

您需要首先初始化客户端。像这样的

GoogleApiClient googleApiClient = new GoogleApiClient.Builder(this)
    .enableAutoManage(this /* FragmentActivity */,
                  this /* OnConnectionFailedListener */)
    .addApi(Drive.API)
    .addScope(Drive.SCOPE_FILE)
    .build();

检查