问java.lang.NullPointerException:尝试调用虚方法分析

EN

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.davidavila.myapplication, PID: 6492
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.davidavila.myapplication/com.example.davidavila.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File com.parse.ParsePlugins.getParseDir()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File com.parse.ParsePlugins.getParseDir()' on a null object reference
        at com.parse.ParseCorePlugins.getCurrentInstallationController(ParseCorePlugins.java:267)
        at com.parse.ParseInstallation.getCurrentInstallationController(ParseInstallation.java:56)
        at com.parse.ParseInstallation.getCurrentInstallation(ParseInstallation.java:62)
        at com.example.davidavila.myapplication.MainActivity.onCreate(MainActivity.java:21)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
I/Process: Sending signal. PID: 6492 SIG: 9

    package com.example.davidavila.myapplication;



    import com.parse.Parse;
    import com.parse.ParseInstallation;

    import android.content.Intent;
    import android.support.v7.app.AppCompatActivity; 
    import android.os.Bundle;
    import android.view.View;

    public class MainActivity extends AppCompatActivity {



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

        ParseInstallation.getCurrentInstallation().saveInBackground();
        Parse.enableLocalDatastore(this);

        Parse.initialize (new Parse.Configuration.Builder(this)
                .applicationId("1b5f82b054262c169a8bcc4b5a1f379cbac8bfd5")
                .clientKey("f9f3b809dbada7fb5ed7793630e21893fb80fea3")
                .server("http://13.58.197.143:80/parse/")
                .build()
        );


    }
        public void buttonMain (View view) {
            Intent intent = new Intent(this, landingPage.class);
            startActivity(intent);
        }
}