CardView NullPointerException onClickListener
CardView NullPointerException onClickListener
提问于 2018-06-02 06:28:36
我试图在CardView上实现一个setOnClickListener方法，但每当我切换设备的方向时，我都会得到一个空异常(如果我以纵向或横向模式启动，效果都很好)：
虚方法:无法启动activity ComponentInfo{com.navajoinc.navajoinc.navfeedbackapp/com.navajoinc.navajoinc.navfeedbackapp.feedBackCardView}：java.lang.NullPointerException:尝试在空对象引用上调用虚方法的空方法
我的Java类是：
public class feedBackCardView extends FragmentActivity {
CardView neutralCustomer;
CardView happyCustomer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_feed_back_card_view);
neutralCustomer = findViewById(R.id.neutralCustomer);
happyCustomer = findViewById(R.id.happyCard);
neutralCustomer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(feedBackCardView.this, thank_you_positive.class);
startActivity(intent);
}
});
happyCustomer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(feedBackCardView.this, thank_you_positive.class);
startActivity(intent);
}
});
}
public void unsatisfiedCutomerSelectionMethod(View v){
singleChoiceClass unsatisfied_customer_dialog = new singleChoiceClass();
unsatisfied_customer_dialog.show(getFragmentManager(), "unsatisfied_customer_dialog");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the main_menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.contactus:
Intent callIntent = new Intent(Intent.ACTION_DIAL);
callIntent.setData(Uri.parse("tel:800.525.5097"));
startActivity(callIntent);
break;
case R.id.visitsite:
Intent siteIntent = new Intent(Intent.ACTION_VIEW);
siteIntent.setData(Uri.parse("http://navajoinc.com"));
startActivity(siteIntent);
break;
default:
return super.onOptionsItemSelected(item);
}
return true;
}
}活动XML：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".feedBackCardView"
android:padding="10dp"
android:background="@color/colorWhiteSmoke"
android:orientation="vertical">
<ScrollView
android:layout_width="match_parent"
android:fillViewport="true"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="14dp"
android:layout_gravity="center"
android:text="Please tap a response :"
android:textColor="@color/colorLightGrey" />
<LinearLayout
android:clipToPadding="false"
android:gravity="center"
android:clickable="false"
android:layout_gravity="center"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.CardView
android:id="@+id/happyCard"
android:foreground="?android:selectableItemBackground"
android:clickable="true"
android:layout_width="160dp"
android:layout_height="190dp"
android:layout_margin="10dp"
app:cardElevation="3dp"
app:cardBackgroundColor="@color/cardview_light_background"
app:cardCornerRadius="3dp"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/colorWhite"
android:gravity="center">
<ImageView
android:layout_width="64dp"
android:layout_height="64dp"
android:background="@drawable/happy_face"
android:padding="10dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold"
android:layout_marginTop="10dp"
android:textColor="@color/colorLightGrey"
android:text="Happy Customer"/>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@color/cardview_light_background"
android:layout_margin="2dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="11dp"
android:textColor="@color/colorTextGrey"
android:text="I have had a happy experience"/>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
<LinearLayout
android:id="@+id/neutralLayout"
android:clipToPadding="false"
android:gravity="center"
android:orientation="horizontal"
android:clickable="false"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.CardView
android:id="@+id/neutralCustomer"
android:foreground="?android:selectableItemBackground"
android:clickable="true"
android:layout_width="160dp"
android:layout_height="190dp"
android:layout_margin="10dp"
app:cardElevation="3dp"
app:cardBackgroundColor="@color/cardview_light_background"
app:cardCornerRadius="3dp"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/colorWhite"
android:gravity="center">
<ImageView
android:layout_width="64dp"
android:layout_height="64dp"
android:background="@drawable/neutral_face"
android:padding="10dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold"
android:layout_marginTop="10dp"
android:textColor="@color/colorLightGrey"
android:text="Neutral Customer"/>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@color/cardview_light_background"
android:layout_margin="2dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="11dp"
android:textColor="@color/colorTextGrey"
android:text="My experience was neutral"/>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
<LinearLayout
android:clipToPadding="false"
android:gravity="center"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.CardView
android:foreground="?android:selectableItemBackground"
android:clickable="true"
android:onClick="unsatisfiedCutomerSelectionMethod"
android:layout_width="160dp"
android:layout_height="190dp"
android:layout_margin="10dp"
app:cardElevation="3dp"
app:cardBackgroundColor="@color/cardview_light_background"
app:cardCornerRadius="3dp"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/colorWhite"
android:gravity="center">
<ImageView
android:layout_width="64dp"
android:layout_height="64dp"
android:background="@drawable/angry_face"
android:padding="10dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold"
android:layout_marginTop="10dp"
android:textColor="@color/colorLightGrey"
android:text="Unsatisfied Customer"/>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@color/cardview_light_background"
android:layout_margin="2dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="11dp"
android:textColor="@color/colorTextGrey"
android:text="My experience was unpleasant"/>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
</LinearLayout>
</ScrollView>
</LinearLayout>我在Stackoverflow和其他网站上尝试了许多解决方案，但都没有奏效？你能帮我解决这个问题吗？
回答 1
Stack Overflow用户
发布于 2018-06-02 07:14:48
我试过这段代码，它正在工作。即使在旋转之后。但是，我更改了onclick方法的实现，只显示一个toast，而不是启动一个intent，因为您没有提供这些类。我还省略了所有与菜单相关的代码。
另外，如果要在代码中设置clickable=true，为什么还要在卡片视图上设置onClickListener属性？这是多余的。此外，我认为没有任何理由在您的<LinearLayout>标记中断言clickable=false。
我认为你没有提供足够的信息来定位错误，或者它与没有提供的类有关。应用程序是简单地在旋转时崩溃，还是在你尝试点击后崩溃？您确定崩溃与旋转有关，而不是试图启动新活动吗？
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50651723
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