为什么android studio无法打开我的活动？

Question

我试图创建一个意图声明，以便在我的卡片上打开一个名为“ Activtyquizs”的活动。但是，我从logcat收到以下错误：“无法启动活动ComponentInfo {com.avinashdavid.trivialtrivia / com.avinashdavid.trivialtrivia.UI.Activityquizs}：java.lang.NullPointerException：尝试调用虚拟方法'android。在空对象引用上的view.ViewGroup $ LayoutParams android.widget.ImageView.getLayoutParams（）'”。我不能完全确定此错误是什么意思，因此我将尽可能多地引用相关代码。

我想从代码开始的活动：

CardView startCardview = (CardView)findViewById(R.id.card_view_start_game);
        startCardview.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(ActivityWelcomePage.this, Activityquizs.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent);
            }
        });

我想通过有问题的xml文件卡打开活动：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    android:id="@+id/activity_welcome_page"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:background="@drawable/redbck"
    android:layout_height="match_parent"
    tools:context="com.avinashdavid.trivialtrivia.UI.ActivityWelcomePage"
    xmlns:app="http://schemas.android.com/apk/res-auto">


    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" />
    </ScrollView>

    <LinearLayout
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
                  android:layout_below="@+id/toolbar"
                  android:orientation="vertical"
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  android:gravity="center_horizontal">


        <android.support.v7.widget.CardView
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_view_statistics"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            card_view:cardCornerRadius="2dp"
            android:layout_marginBottom="@dimen/activity_vertical_margin"
            card_view:cardUseCompatPadding="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="#00d4ff">


                <RelativeLayout
                    android:id="@+id/imagecontainer2"
                    android:layout_alignParentStart="true"
                    android:layout_alignParentLeft="true"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:paddingTop="@dimen/activity_vertical_margin"
                    android:paddingBottom="@dimen/activity_vertical_margin"
                    android:paddingLeft="@dimen/activity_horizontal_margin"
                    android:paddingStart="@dimen/activity_horizontal_margin"
                    android:paddingEnd="@dimen/activity_horizontal_margin"
                    android:paddingRight="@dimen/activity_horizontal_margin">

                    <ImageView
                        android:id="@+id/imageview_statistics"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:adjustViewBounds="true"
                        android:scaleType="fitCenter"/>

                </RelativeLayout>

                <LinearLayout
                    android:layout_alignParentTop="true"
                    android:layout_toRightOf="@+id/imagecontainer2"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical"
                    android:gravity="center_vertical">

                    <TextView
                        style="@style/WelcomeHeadings"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Online Mode"
                        android:textColor="#fff"
                        android:textStyle="bold" />

                    <TextView
                        style="@style/StatsContent"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:paddingBottom="0dp"
                        android:text="@string/statistics_subtitle"
                        android:textColor="#fff" />

                </LinearLayout>

            </RelativeLayout>

        </android.support.v7.widget.CardView>
        <android.support.v7.widget.CardView
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_view_statistics2"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            card_view:cardCornerRadius="2dp"
            android:layout_marginBottom="@dimen/activity_vertical_margin"
            card_view:cardUseCompatPadding="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="#00d4ff">


                <RelativeLayout
                    android:id="@+id/imagecontainer22"
                    android:layout_alignParentStart="true"
                    android:layout_alignParentLeft="true"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:paddingTop="@dimen/activity_vertical_margin"
                    android:paddingBottom="@dimen/activity_vertical_margin"
                    android:paddingLeft="@dimen/activity_horizontal_margin"
                    android:paddingStart="@dimen/activity_horizontal_margin"
                    android:paddingEnd="@dimen/activity_horizontal_margin"
                    android:paddingRight="@dimen/activity_horizontal_margin">

                    <ImageView
                        android:id="@+id/imageview_statistics2"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:adjustViewBounds="true"
                        android:scaleType="fitCenter"/>

                </RelativeLayout>

                <LinearLayout
                    android:layout_alignParentTop="true"
                    android:layout_toRightOf="@+id/imagecontainer22"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical"
                    android:gravity="center_vertical">

                    <TextView
                        style="@style/WelcomeHeadings"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Online Mode"
                        android:textColor="#fff"
                        android:textStyle="bold" />

                    <TextView
                        style="@style/StatsContent"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:paddingBottom="0dp"
                        android:text="@string/statistics_subtitle"
                        android:textColor="#fff" />

                </LinearLayout>

            </RelativeLayout>

        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_view_instructions"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            card_view:cardCornerRadius="2dp"
            android:layout_marginBottom="@dimen/activity_vertical_margin"
            card_view:cardUseCompatPadding="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="#00d4ff">


                <RelativeLayout
                    android:id="@+id/imagecontainer3"
                    android:layout_alignParentStart="true"
                    android:layout_alignParentLeft="true"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:paddingTop="@dimen/activity_vertical_margin"
                    android:paddingBottom="@dimen/activity_vertical_margin"
                    android:paddingLeft="@dimen/activity_horizontal_margin"
                    android:paddingStart="@dimen/activity_horizontal_margin"
                    android:paddingEnd="@dimen/activity_horizontal_margin"
                    android:paddingRight="@dimen/activity_horizontal_margin">

                    <ImageView
                        android:id="@+id/imageview_instructions"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:adjustViewBounds="true"
                        android:scaleType="fitCenter"/>

                </RelativeLayout>

                <LinearLayout
                    android:layout_alignParentTop="true"
                    android:layout_toRightOf="@+id/imagecontainer3"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical"
                    android:gravity="center_vertical">

                    <TextView
                        style="@style/WelcomeHeadings"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Report a Bug"
                        android:textColor="#fff"
                        android:textStyle="bold" />

                    <TextView
                        style="@style/StatsContent"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:paddingBottom="0dp"
                        android:text="@string/instructions_subtitle"
                        android:textColor="#fff" />

                </LinearLayout>

            </RelativeLayout>

        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_view_acknowledgments"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            card_view:cardCornerRadius="2dp"
            android:layout_marginBottom="@dimen/activity_vertical_margin"
            card_view:cardUseCompatPadding="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="#00d4ff">


                <RelativeLayout
                    android:id="@+id/imagecontainer4"
                    android:layout_alignParentStart="true"
                    android:layout_alignParentLeft="true"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:paddingTop="@dimen/activity_vertical_margin"
                    android:paddingBottom="@dimen/activity_vertical_margin"
                    android:paddingLeft="@dimen/activity_horizontal_margin"
                    android:paddingStart="@dimen/activity_horizontal_margin"
                    android:paddingEnd="@dimen/activity_horizontal_margin"
                    android:paddingRight="@dimen/activity_horizontal_margin">

                    <ImageView
                        android:id="@+id/imageview_acknowledgments"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:adjustViewBounds="true"
                        android:scaleType="fitCenter"/>

                </RelativeLayout>

                <LinearLayout
                    android:layout_alignParentTop="true"
                    android:layout_toRightOf="@+id/imagecontainer4"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical"
                    android:gravity="center_vertical">

                    <TextView
                        style="@style/WelcomeHeadings"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Terms and Conditions"
                        android:textColor="#fff"
                        android:textStyle="bold" />

                    <TextView
                        style="@style/StatsContent"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:paddingBottom="0dp"
                        android:text="@string/acknowledgements_subtitle"
                        android:textColor="#fff" />

                </LinearLayout>

            </RelativeLayout>

        </android.support.v7.widget.CardView>



    </LinearLayout>

    <android.support.v7.widget.CardView
        android:id="@+id/card_view_start_game"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentTop="true"
        android:layout_gravity="center"
        android:layout_marginTop="97dp"
        android:layout_weight="1"
        app:cardCornerRadius="2dp"
        app:cardUseCompatPadding="true">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#00d4ff">


            <RelativeLayout
                android:id="@+id/imagecontainer1"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:paddingBottom="@dimen/activity_vertical_margin"
                android:paddingEnd="@dimen/activity_horizontal_margin"
                android:paddingLeft="@dimen/activity_horizontal_margin"
                android:paddingRight="@dimen/activity_horizontal_margin"
                android:paddingStart="@dimen/activity_horizontal_margin"
                android:paddingTop="@dimen/activity_vertical_margin">

                <ImageView
                    android:id="@+id/imageview_start"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:adjustViewBounds="true"
                    android:scaleType="fitCenter" />

            </RelativeLayout>

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_alignParentTop="true"
                android:layout_toRightOf="@+id/imagecontainer1"
                android:gravity="center_vertical"
                android:orientation="vertical">

                <TextView
                    android:id="@+id/startgame"
                    style="@style/WelcomeHeadings"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="@string/start_game"
                    android:textColor="#fff"
                    android:textStyle="bold" />

                <TextView
                    style="@style/StatsContent"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingBottom="0dp"
                    android:text="@string/start_subtitle"
                    android:textColor="#fff" />

            </LinearLayout>

        </RelativeLayout>

    </android.support.v7.widget.CardView>
</RelativeLayout> 

整个堆栈跟踪：

12-14 19:29:13.728 23331-23331/com.avinashdavid.trivialtrivia E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.avinashdavid.trivialtrivia, PID: 23331
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.avinashdavid.trivialtrivia/com.avinashdavid.trivialtrivia.UI.Activityquizs}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference
        at com.avinashdavid.trivialtrivia.UI.Activityquizs.onCreate(Activityquizs.java:35)
        at android.app.Activity.performCreate(Activity.java:7009)
        at android.app.Activity.performCreate(Activity.java:7000)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)