如何在 android 中使用 CustomAdapter 创建 Spinner-list
How to create Spinner-list using CustomAdapter in android
在我的应用程序中，我想使用 CustomAdapter class 创建 SpinnerList，为此我写了下面的代码，但是当我点击微调器列表时，数组列表图像没有加载到微调器列表中，就像我的一样屏幕下方为什么会出现此问题？
main_layout.xml:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dip"
android:text="Category:"
android:layout_marginBottom="5dp"/>
<Spinner
android:id="@+id/spinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
主要活动：-
public class MainActivity extends AppCompatActivity {
public static final String[] titles = new String[] { "Strawberry",
"Banana", "Orange", "Hello" };
public static final Integer[] images = { R.drawable.image1,
R.drawable.image2, R.drawable.image3, R.drawable.image4 };
Spinner spinner;
List<RowItem> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
rowItems = new ArrayList<RowItem>();
for (int i = 0; i < titles.length; i++) {
RowItem item = new RowItem(titles[i],images[i]);
rowItems.add(item);
}
spinner = (Spinner)findViewById(R.id.spinner);
CustomAdapter adapter = new CustomAdapter(MainActivity.this,
R.layout.listitems_layout, R.id.title, rowItems);
spinner.setAdapter(adapter);
}
}
listitems_layout.xml:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<ImageView
android:id="@+id/icon"
android:layout_width="80dp"
android:layout_height="80dp"
android:src="@drawable/image1"
android:padding="10dp"
/>
<TextView
android:layout_marginTop="30dp"
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/icon"
android:textColor="#CC0033"
android:text="Strawberry"
android:textSize="16dp" />
</LinearLayout>
自定义适配器：-
package com.example.venkat.spinnerexample1;
import android.app.Activity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.view.LayoutInflater;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
public class CustomAdapter extends ArrayAdapter<RowItem> {
LayoutInflater flater;
public CustomAdapter(Activity context,int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
flater = context.getLayoutInflater();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
RowItem rowItem = getItem(position);
View rowview = flater.inflate(R.layout.listitems_layout,null,true);
TextView txtTitle = (TextView) rowview.findViewById(R.id.title);
txtTitle.setText(rowItem.getTitle());
ImageView imageView = (ImageView) rowview.findViewById(R.id.icon);
imageView.setImageResource(rowItem.getImageId());
return rowview;
}
}
行项目：-
package com.example.venkat.spinnerexample1;
public class RowItem {
private int ImageId;
private String Title;
public RowItem(String Title,int ImageId){
this.Title = Title;
this.ImageId = ImageId;
}
public String getTitle(){
return Title;
}
public void setTitle(String Title){
this.Title = Title;
}
public int getImageId(){
return ImageId;
}
public void setImageId(int ImageId){
this.ImageId = ImageId;
}
@Override
public String toString() {
return Title ;
}
}
画面：-
---
在你的适配器构造函数中，也发送 textview 的 id
public CustomAdapter(Activity context,int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
flater = context.getLayoutInflater();
}
通过
调用它
CustomAdapter adapter = new CustomAdapter(MainActivity.this,
R.layout.listitems_layout, R.id.title, rowItems);
编辑
您的图像没有显示，因为您没有覆盖 getDropdownView() 方法。当下拉菜单可见时，此方法决定子项的布局。所以将此方法添加到您的适配器
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
if(convertView == null){
convertView = flater.inflate(R.layout.list_itemslayout,parent, false);
}
RowItem rowItem = getItem(position);
TextView txtTitle = (TextView) convertView.findViewById(R.id.title);
txtTitle.setText(rowItem.getTitle());
ImageView imageView = (ImageView) convertView.findViewById(R.id.icon);
imageView.setImageResource(rowItem.getImageId());
return convertView;
}
建议
在您的 getView() 中检查 (convertview == null)。它可能不会对这个小型适配器产生任何影响，但如果您的适配器有更多项目，则会影响性能。
编辑
要将微调器下拉列表置于锚点下方，请使用
android:overlapAnchor="false" 在你的转盘里
像这样改变你的适配器
public class CustomAdapter extends ArrayAdapter<RowItem> {
LayoutInflater flater;
public CustomAdapter(Activity context, int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
// flater = context.getLayoutInflater();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
return rowview(convertView,position);
}
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
return rowview(convertView,position);
}
private View rowview(View convertView , int position){
RowItem rowItem = getItem(position);
viewHolder holder ;
View rowview = convertView;
if (rowview==null) {
holder = new viewHolder();
flater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
rowview = flater.inflate(R.layout.listitems_layout, null, false);
holder.txtTitle = (TextView) rowview.findViewById(R.id.title);
holder.imageView = (ImageView) rowview.findViewById(R.id.icon);
rowview.setTag(holder);
}else{
holder = (viewHolder) rowview.getTag();
}
holder.imageView.setImageResource(rowItem.getImageId());
holder.txtTitle.setText(rowItem.getTitle());
return rowview;
}
private class viewHolder{
TextView txtTitle;
ImageView imageView;
}
}
我们也可以使用ViewHolder Pattern
public class TypeAdapter extends ArrayAdapter<RowItem> {
public TypeAdapter(@NonNull Context context, ArrayList<Calendar> objects) {
super(context, R.layout.calendar_type_row, objects);
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
return rowView(convertView, position);
}
@Override
public View getDropDownView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
return rowView(convertView, position);
}
class ViewHolder extends RecyclerView.ViewHolder {
//Views
public ViewHolder(@NonNull View itemView) {
super(itemView);
//Init Views by itemView.findViewById
}
}
private View rowView(View convertView, int position) {
if(convertView==null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.calendar_type_row,null);
}
RowItem rowType = getItem(position);
ViewHolder viewHolder = new ViewHolder(convertView);
//Setup Values
return convertView;
}
}
在我的应用程序中，我想使用 CustomAdapter class 创建 SpinnerList，为此我写了下面的代码，但是当我点击微调器列表时，数组列表图像没有加载到微调器列表中，就像我的一样屏幕下方为什么会出现此问题？
main_layout.xml:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dip"
android:text="Category:"
android:layout_marginBottom="5dp"/>
<Spinner
android:id="@+id/spinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
主要活动：-
public class MainActivity extends AppCompatActivity {
public static final String[] titles = new String[] { "Strawberry",
"Banana", "Orange", "Hello" };
public static final Integer[] images = { R.drawable.image1,
R.drawable.image2, R.drawable.image3, R.drawable.image4 };
Spinner spinner;
List<RowItem> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
rowItems = new ArrayList<RowItem>();
for (int i = 0; i < titles.length; i++) {
RowItem item = new RowItem(titles[i],images[i]);
rowItems.add(item);
}
spinner = (Spinner)findViewById(R.id.spinner);
CustomAdapter adapter = new CustomAdapter(MainActivity.this,
R.layout.listitems_layout, R.id.title, rowItems);
spinner.setAdapter(adapter);
}
}
listitems_layout.xml:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<ImageView
android:id="@+id/icon"
android:layout_width="80dp"
android:layout_height="80dp"
android:src="@drawable/image1"
android:padding="10dp"
/>
<TextView
android:layout_marginTop="30dp"
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/icon"
android:textColor="#CC0033"
android:text="Strawberry"
android:textSize="16dp" />
</LinearLayout>
自定义适配器：-
package com.example.venkat.spinnerexample1;
import android.app.Activity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.view.LayoutInflater;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
public class CustomAdapter extends ArrayAdapter<RowItem> {
LayoutInflater flater;
public CustomAdapter(Activity context,int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
flater = context.getLayoutInflater();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
RowItem rowItem = getItem(position);
View rowview = flater.inflate(R.layout.listitems_layout,null,true);
TextView txtTitle = (TextView) rowview.findViewById(R.id.title);
txtTitle.setText(rowItem.getTitle());
ImageView imageView = (ImageView) rowview.findViewById(R.id.icon);
imageView.setImageResource(rowItem.getImageId());
return rowview;
}
}
行项目：-
package com.example.venkat.spinnerexample1;
public class RowItem {
private int ImageId;
private String Title;
public RowItem(String Title,int ImageId){
this.Title = Title;
this.ImageId = ImageId;
}
public String getTitle(){
return Title;
}
public void setTitle(String Title){
this.Title = Title;
}
public int getImageId(){
return ImageId;
}
public void setImageId(int ImageId){
this.ImageId = ImageId;
}
@Override
public String toString() {
return Title ;
}
}
画面：-
---
在你的适配器构造函数中，也发送 textview 的 id
public CustomAdapter(Activity context,int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
flater = context.getLayoutInflater();
}
通过
调用它CustomAdapter adapter = new CustomAdapter(MainActivity.this,
R.layout.listitems_layout, R.id.title, rowItems);
编辑 您的图像没有显示，因为您没有覆盖 getDropdownView() 方法。当下拉菜单可见时，此方法决定子项的布局。所以将此方法添加到您的适配器
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
if(convertView == null){
convertView = flater.inflate(R.layout.list_itemslayout,parent, false);
}
RowItem rowItem = getItem(position);
TextView txtTitle = (TextView) convertView.findViewById(R.id.title);
txtTitle.setText(rowItem.getTitle());
ImageView imageView = (ImageView) convertView.findViewById(R.id.icon);
imageView.setImageResource(rowItem.getImageId());
return convertView;
}
建议 在您的 getView() 中检查 (convertview == null)。它可能不会对这个小型适配器产生任何影响，但如果您的适配器有更多项目，则会影响性能。
编辑 要将微调器下拉列表置于锚点下方，请使用
android:overlapAnchor="false" 在你的转盘里
像这样改变你的适配器
public class CustomAdapter extends ArrayAdapter<RowItem> {
LayoutInflater flater;
public CustomAdapter(Activity context, int resouceId, int textviewId, List<RowItem> list){
super(context,resouceId,textviewId, list);
// flater = context.getLayoutInflater();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
return rowview(convertView,position);
}
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
return rowview(convertView,position);
}
private View rowview(View convertView , int position){
RowItem rowItem = getItem(position);
viewHolder holder ;
View rowview = convertView;
if (rowview==null) {
holder = new viewHolder();
flater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
rowview = flater.inflate(R.layout.listitems_layout, null, false);
holder.txtTitle = (TextView) rowview.findViewById(R.id.title);
holder.imageView = (ImageView) rowview.findViewById(R.id.icon);
rowview.setTag(holder);
}else{
holder = (viewHolder) rowview.getTag();
}
holder.imageView.setImageResource(rowItem.getImageId());
holder.txtTitle.setText(rowItem.getTitle());
return rowview;
}
private class viewHolder{
TextView txtTitle;
ImageView imageView;
}
}
我们也可以使用ViewHolder Pattern
public class TypeAdapter extends ArrayAdapter<RowItem> {
public TypeAdapter(@NonNull Context context, ArrayList<Calendar> objects) {
super(context, R.layout.calendar_type_row, objects);
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
return rowView(convertView, position);
}
@Override
public View getDropDownView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
return rowView(convertView, position);
}
class ViewHolder extends RecyclerView.ViewHolder {
//Views
public ViewHolder(@NonNull View itemView) {
super(itemView);
//Init Views by itemView.findViewById
}
}
private View rowView(View convertView, int position) {
if(convertView==null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.calendar_type_row,null);
}
RowItem rowType = getItem(position);
ViewHolder viewHolder = new ViewHolder(convertView);
//Setup Values
return convertView;
}
}