当我按意图发送变量时app崩溃了

Question

这是我的第一个应用程序，我搜索了几个关于该主题的帖子，但没有一个解决了我的问题...我创建了一个按钮，用于将变量（String）从一个活动发送到另一个活动，但按下它会导致应用程序崩溃......这是第一个活动的代码：

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

public class PrimeraPregunta extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    final Button btSeisTres;

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_primera_pregunta);

    btSeisTres = (Button)findViewById(R.id.btSeisTres);

    btSeisTres.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String eleccionPuna = "6300";
            Intent intent = new Intent(PrimeraPregunta.this, SegundaPregunta.class);
            intent.putExtra("envioUno", eleccionPuna);
            startActivity(intent);
       }
      });
     }
    }

这是第二项活动的代码：

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

public class SegundaPregunta extends AppCompatActivity {
TextView textViewName;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_segunda_pregunta);
    TextView textViewName = (TextView) findViewById(R.id.textViewName);
    Intent intent = getIntent();
    String eleccionPuna = intent.getExtras().getString("envioUno");
    textViewName.setText(eleccionPuna);

    }

}

最后，这是AndroidManifest.xml

   <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.xxkuakxxgmail.knowyourchamp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".PrimeraPregunta" />
        <activity android:name=".SegundaPregunta"/>
    </application>
</manifest>

编辑：这是堆栈跟踪：

11-28 17:50:05.941 9837-9837/com.xxkuakxxgmail.knowyourchamp E/AndroidRuntime: FATAL EXCEPTION: main
                                                                           Process: com.xxkuakxxgmail.knowyourchamp, PID: 9837
                                                                           java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xxkuakxxgmail.knowyourchamp/com.xxkuakxxgmail.knowyourchamp.SegundaPregunta}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
                                                                               at android.app.ActivityThread.-wrap12(ActivityThread.java)
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                               at android.os.Looper.loop(Looper.java:154)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
                                                                            Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                                                                               at com.xxkuakxxgmail.knowyourchamp.SegundaPregunta.onCreate(SegundaPregunta.java:17)
                                                                               at android.app.Activity.performCreate(Activity.java:6705)
                                                                               at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
                                                                               at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                               at android.os.Looper.loop(Looper.java:154) 
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077) 
                                                                               at java.lang.reflect.Method.invoke(Native Method) 
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)