我是Android新手，我正在开发一个购物清单应用程序，但我遇到了一些麻烦。
现在，我已经创建了一个包含图像和名称字段的自定义listView。我还制作了一个自定义对象GroceryItem来填充listViews。
我希望用户能够从listView中选择GroceryItems，并搜索列表。这是我的listView的自定义适配器。
class CustomAdapter extends ArrayAdapter<GroceryItem> implements Filterable
{
private ArrayList<GroceryItem> mObjects;
private ArrayFilter mFilter;
private ArrayList<GroceryItem> mOriginalValues;
CustomAdapter(@NonNull Context context, int resource, @NonNull ArrayList<GroceryItem> inputValues) {
super(context, resource, inputValues);
mObjects = new ArrayList<>(inputValues);
}
public void setBackup(){
mOriginalValues = new ArrayList<GroceryItem>();
mOriginalValues.addAll(mObjects);
}
@SuppressLint("ClickableViewAccessibility")
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
final GroceryItem currentGroceryItem = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
if (convertView == null) {
convertView = getLayoutInflater().inflate(R.layout.custom_layout, parent, false);
}
// Lookup view for data population
ImageView groceryImage = (ImageView) convertView.findViewById(R.id.groceryImage);
TextView groceryNameText = (TextView) convertView.findViewById(R.id.groceryName);
LinearLayout overallItem = (LinearLayout) convertView.findViewById(R.id.linearLayout);
// Populate the data into the template view using data
groceryImage.setImageResource(currentGroceryItem.getImageID());
groceryNameText.setText(currentGroceryItem.getName());
// Set onClickListener for overallItem
overallItem.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
searchBar.clearFocus();
// Changes the selection status of the GroceryItem
currentGroceryItem.toggle();
// Changes the colour of the background accordingly (to show selection)
if(currentGroceryItem.isSelected()){
v.setBackgroundColor(0xFF83B5C7);
} else{
v.setBackgroundColor(0xFFFFFFFF);
}
}
});
// Return the completed view to render on screen
return convertView;
}
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////FOR SEARCH FUNCTIONALITY////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
public View getViewByPosition(int pos, ListView myListView) {
final int firstListItemPosition = myListView.getFirstVisiblePosition();
final int lastListItemPosition = firstListItemPosition + myListView.getChildCount() - 1;
if (pos < firstListItemPosition || pos > lastListItemPosition ) {
return getView(pos, null, myListView);
} else {
final int childIndex = pos - firstListItemPosition;
return myListView.getChildAt(childIndex);
}
}
public void fixToggling(){
runOnUiThread(new Runnable() {
@Override
public void run() {
for(int i = 0; i < getCount(); ++i){
// Finds view at index i in listView, which is a global variable
View view = getViewByPosition(i, listView);
if(getItem(i).isSelected()){
view.setBackgroundColor(0XFF83B5C7);
} else{
view.setBackgroundColor(0xFFFFFFFF);
}
}
}
});
}
// The following function reverses the filter (sets everything to default)
public void reverseFilter(){
//Replaces mObjects with mOriginal Values
mObjects.clear();
mObjects.addAll(mOriginalValues);
//Loads mObjects (now filled with the original items) into the adapter
this.clear();
this.addAll(mObjects);
fixToggling();
}
// The following function applies a filter given a query
public void applyFilter(String query) {
if(query == null || query.length() == 0){
reverseFilter();
} else{
// Creates a new array filter
mFilter = new ArrayFilter();
// performs the filters, and publishes the result (i.e. writes the result into
// mObjects)
mFilter.publishResults(query, mFilter.performFiltering(query));
// Clears current content of the adapter
this.clear();
// Fills the adapter with the content of the filtered result
this.addAll(mObjects);
fixToggling();
}
}
private class ArrayFilter extends Filter {
@Override
protected FilterResults performFiltering(CharSequence prefix) {
final FilterResults results = new FilterResults();
if(mOriginalValues == null){
mOriginalValues = new ArrayList<>(mObjects);
}
// If there is no input query
if (prefix == null || prefix.length() == 0) {
// Make a copy of mOriginalValues into the list
final ArrayList<GroceryItem> list;
list = new ArrayList<>(mOriginalValues);
// Set the FilterResults value to the copy of mOriginalValues
results.values = list;
results.count = list.size();
// If there is an input query (at least one character in length)
} else {
// Converts the query to a lowercase String
final String prefixString = prefix.toString().toLowerCase();
// Makes a copy of mOriginalValues into the ArrayList "values"
final ArrayList<GroceryItem> values;
values = new ArrayList<>(mOriginalValues);
final int count = values.size();
// Makes a new empty ArrayList
final ArrayList<GroceryItem> newValues = new ArrayList<>();
// Iterates through the number of elements in mOriginalValues
for (int i = 0; i < count; i++) {
// Gets the GroceryItem element at position i from mOriginalValues' copy
final GroceryItem value = values.get(i);
// Extracts the name of the GroceryItem element into valueText
final String valueText = value.getName().toLowerCase();
// First match against the whole, non-splitted value
if (valueText.startsWith(prefixString)) {
newValues.add(value);
}
else {
// Splits the one String into all its constituent words
final String[] words = valueText.split(" ");
// If any of the constituent words starts with the prefix, adds them
for (String word : words) {
if (word.startsWith(prefixString)) {
newValues.add(value);
break;
}
}
}
}
// Sets the FilterResult value to the newValues ArrayList. mOriginalValues is
// preserved.
results.values = newValues;
results.count = newValues.size();
// Changes mObjects from (potentially) the original items or the previously filtered
// results to the new filtered results. Needs to be loaded into the adapter still.
mObjects.clear();
mObjects.addAll(newValues);
}
return results;
}
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
notifyDataSetChanged();
}
}
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
}
这是我遇到的问题。我现在有四种杂货：Apple，Banana，Grapes和Mango。如果我选择葡萄，一切都很好。它显示带有蓝色背景的葡萄和带有白色背景的所有其他物品。当我开始在搜索栏中输入“gr”时，一切正常。我只看到Grapes，项目显示为选中（蓝色背景）。当我输入“grm”时，一切都消失了，没有选择任何内容。但是，当我退回一个角色然后回到“gr”时，它会向我显示Grapes，但它不再被选中。
另一个类似的问题。再次从Apple，Banana，Grapes和Mango开始，如果我选择Grapes并搜索“b”，我会选择Banana。大。现在，当我选择Banana时，它会将其显示为已选中。但是，一旦我退格，我会回到完整的项目列表，只选择Grapes。
我编写了fixToggling（）函数来迭代每个视图并根据需要修复背景颜色。我还做了一些调试，以了解每个groceryItem的isSelected布尔值是否被正确记录，因此应用程序不记得应该选择或未选择哪些应用程序不是问题。出于某种原因，切换只是关闭。
有人可以帮忙吗？我只想让用户同时使用搜索功能和项目选择。
答案 0 :(得分：0)
试试这个适配器代码：
.btn .dropdown-content希望有所帮助！