[英]Why I am getting NullPointerException on ImageView?
My code is as follows: 我的代码如下:
activity_for_me.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ListView
android:id="@+id/recco_list"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</ListView>
<ImageView
android:id="@+id/checkin"
android:layout_width="wrap_content"
android:layout_height="80dp"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="20dp"
android:onClick="ClickCheckIn"
android:src="@drawable/checkin" />
</RelativeLayout>
recco_list.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@layout/nine_patch" >
<ImageView
android:id="@+id/outlet_icon"
android:layout_marginLeft="15dp"
android:layout_height="55dp"
android:layout_width="55dp"
android:layout_marginTop="10dp"/>
<TextView
android:id="@+id/distance"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_marginLeft="15dp"
android:hint="Distance"
/>
<TextView
android:id="@+id/outlet_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/outlet_icon"
android:layout_toLeftOf="@id/distance"
android:layout_marginLeft = "15dip"
android:hint="outlet"
/>
<TextView
android:id="@+id/reward"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/outlet_name"
android:layout_toRightOf="@id/outlet_icon"
android:layout_toLeftOf="@id/distance"
android:layout_marginLeft = "15dip"
android:layout_marginTop="5dp"
android:textColor="@color/abc_search_url_text_holo"
android:hint="Reward"
/>
<View
android:id="@+id/rule"
android:layout_below="@id/reward"
android:layout_toRightOf="@id/outlet_icon"
android:layout_toLeftOf="@id/distance"
android:layout_width="fill_parent"
android:layout_marginLeft = "15dip"
android:layout_height="1dp"
android:background="#c0c0c0"/>
<ImageView
android:id="@+id/favourite_icon"
android:layout_below="@id/rule"
android:layout_marginLeft="15dp"
android:layout_marginTop="10dp"
android:layout_height="15dp"
android:layout_width="15dp"
android:src="@drawable/heart_empty"/>
<ImageView
android:id="@+id/loc_icon"
android:layout_width="25dp"
android:layout_height="25dp"
android:layout_below="@id/rule"
android:layout_marginLeft = "15dip"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/outlet_icon"
android:src="@drawable/map_pointer"/>
<TextView
android:id="@+id/locality"
android:layout_toRightOf="@id/loc_icon"
android:layout_toLeftOf="@id/distance"
android:layout_below="@id/rule"
android:layout_marginRight="15dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft = "5dip"
android:layout_marginTop="5dp"
android:hint="Locality"
/>
</RelativeLayout>
Activity.java
public class ForMeActivity extends Fragment {
@SuppressLint("ClickableViewAccessibility")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
RelativeLayout rootView = (RelativeLayout) inflater.inflate(
R.layout.activity_for_me, container, false);
ImageView favourite_heart = (ImageView) rootView
.findViewById(R.id.favourite_icon);
favourite_heart.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Toast.makeText(YourActivityName.this,
// "The favorite list would appear on clicking this icon",
// Toast.LENGTH_LONG).show();
System.out.println("Favourite Icon clicked");
}
});
list = (ListView) rootView.findViewById(R.id.recco_list);
ImageView check_in_img = (ImageView) rootView
.findViewById(R.id.checkin);
ImageView outlet_logo = (ImageView) rootView
.findViewById(R.id.outlet_icon);
final String data = getArguments().getString("data");
ForMeFile = new File(getActivity().getExternalFilesDir(filepath),
filename);
final String cookie = getArguments().getString("cookie");
System.out.print(cookie);
check_in_img.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent in = new Intent(getActivity(), CheckInView.class);
startActivity(in);
System.out.println("Checkin Icon clicked");
}
});
}
I want to change image for favourite_icon ImageView
when I click on it. 我想在单击favourite_icon
ImageView
时更改图像。 But as soon as I click on the icon I get NullPointerException
. 但是,一旦我单击该图标,我就会得到
NullPointerException
。 What is the reason that click of check_in_img is working but click of favourite_icon is not working even though the current layout is the one which contains favourite_icon ? 尽管当前布局是包含favourite_icon的布局,但check_in_img的单击仍可正常工作,而favourite_icon的单击却无法正常工作的原因是什么? Other sources of SO says to check the same.
SO的其他来源说要检查相同。
favourite_icon
is a part of recco_list.xml and you are trying to find it in activity_for_me.xml . favourite_icon
是recco_list.xml的一部分,您正在尝试在activity_for_me.xml中找到它。 The view does not exist there and hence, the exception. 该视图不存在,因此是例外。
R.id.favourite_icon
is not there in activity_for_me.xml
. R.id.favourite_icon
在activity_for_me.xml
不存在。
And if you want to access the items in the listview, I suggest you read about ListView and getView(). 而且,如果您想访问列表视图中的项目,建议您阅读有关ListView和getView()的文章。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.