Android 如何访问自定义ListView中的项目
我正在开发一个Android应用程序,我必须实现一个定制的ListView 我有一个包含ListView声明的主布局:Android 如何访问自定义ListView中的项目,android,listview,Android,Listview,我正在开发一个Android应用程序,我必须实现一个定制的ListView 我有一个包含ListView声明的主布局: <ListView android:id="@+id/imageList" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="0.5"> </ListView> 以及自定义行的布局: <?xm
<ListView
android:id="@+id/imageList"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.5">
</ListView>
以及自定义行的布局:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/list_row_selector"
android:padding="8dp">
<LinearLayout
android:id="@+id/titleLL"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/title"
android:textColor="#FF0000"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold" />
</LinearLayout>
<LinearLayout
android:id="@+id/photoList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/titleLL"
android:orientation="horizontal"
android:layout_alignParentStart="true">
<ImageView
android:id="@+id/takePhoto"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:src="@drawable/ico_camera"
android:layout_marginRight="40dp"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true" />
<ImageView
android:id="@+id/thumbnail0"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:layout_alignParentLeft="true"
android:layout_marginRight="40dp" />
<ImageView
android:id="@+id/thumbnail1"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:layout_alignParentLeft="true"
android:layout_marginRight="40dp" />
</LinearLayout>
<ImageView
android:id="@+id/deleteall"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="centerCrop"
android:src="@drawable/ico_menu_delete_photo"
android:layout_below="@+id/titleLL"
android:layout_alignParentEnd="true" />
</RelativeLayout>
public class CustomRow {
private Integer id;
private String title;
public CustomRow() {}
public CustomRow(String ti, Integer id) {
this.id = id;
this.title = ti;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String ti) {
this.title = ti;
}
}
and finally the code of the CustomList:
public class CustomList extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<CustomRow> ListItem;
public CustomList(Activity activity, List<CustomRow> listPhotoItems) {
this.activity = activity;
this.ListItem = listPhotoItems;
}
@Override
public int getCount() {
return ListItem.size();
}
@Override
public Object getItem(int location) {
return ListItem.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.custom_list, null);
ImageView takePhoto = (ImageView) convertView.findViewById(R.id.takePhoto);
TextView title = (TextView) convertView.findViewById(R.id.title);
CustomRow m = ListItem.get(position);
takePhoto.setTag(m.getId());
title.setText(m.getTitle());
return convertView;
}
}
这是自定义行的类:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/list_row_selector"
android:padding="8dp">
<LinearLayout
android:id="@+id/titleLL"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/title"
android:textColor="#FF0000"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold" />
</LinearLayout>
<LinearLayout
android:id="@+id/photoList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/titleLL"
android:orientation="horizontal"
android:layout_alignParentStart="true">
<ImageView
android:id="@+id/takePhoto"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:src="@drawable/ico_camera"
android:layout_marginRight="40dp"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true" />
<ImageView
android:id="@+id/thumbnail0"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:layout_alignParentLeft="true"
android:layout_marginRight="40dp" />
<ImageView
android:id="@+id/thumbnail1"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="center"
android:layout_alignParentLeft="true"
android:layout_marginRight="40dp" />
</LinearLayout>
<ImageView
android:id="@+id/deleteall"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:scaleType="centerCrop"
android:src="@drawable/ico_menu_delete_photo"
android:layout_below="@+id/titleLL"
android:layout_alignParentEnd="true" />
</RelativeLayout>
public class CustomRow {
private Integer id;
private String title;
public CustomRow() {}
public CustomRow(String ti, Integer id) {
this.id = id;
this.title = ti;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String ti) {
this.title = ti;
}
}
and finally the code of the CustomList:
public class CustomList extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<CustomRow> ListItem;
public CustomList(Activity activity, List<CustomRow> listPhotoItems) {
this.activity = activity;
this.ListItem = listPhotoItems;
}
@Override
public int getCount() {
return ListItem.size();
}
@Override
public Object getItem(int location) {
return ListItem.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.custom_list, null);
ImageView takePhoto = (ImageView) convertView.findViewById(R.id.takePhoto);
TextView title = (TextView) convertView.findViewById(R.id.title);
CustomRow m = ListItem.get(position);
takePhoto.setTag(m.getId());
title.setText(m.getTitle());
return convertView;
}
}
问题很简单,我如何在创建CustomRow之前访问ListView的项,而不是在ListView的侦听器中
例如,我想更改ImageView thumbail0的图像
我试过不同的方法,但都不管用
例如:
lv.findviewbydr.id.thumbnail0
或
视图vi=充气机.充气机.布局.自定义列表,空;
vi.findviewbydr.id.thumbnail0
当我尝试实现此代码时,我无法使用解决方案错误occours:
java.lang.NullPointerException:尝试调用虚拟方法
空值上的“android.view.view android.view.view.FindViewByDint”
对象引用
在适配器的getView方法中创建之前,可以访问任何项。此方法绑定每个项。在适配器的getView方法中执行此操作。我无法在适配器getView中执行此操作。@Max为什么不能在适配器getView中执行此操作?ListView的行在膨胀之前不存在,因此在此之前您无法访问它们。因为我需要以友好方式创建/修改行列表中的某些元素,例如更改列表中的图像ImageView@Max是的,这就是getView方法的用途-在必要时对行进行充气,以及在显示每行之前设置其视图属性。