如何解决如何从共享首选项保存和显示项目
说明：
我已经使用共享首选项GSON概念的概念在列表视图中使用“心脏图标”进行保存/取消保存。
My Design(fig.1)
。我只能像 Retrieved titles in a listview (fig.2) 中那样显示标题，但无法检索带有如图3所示标题的心形图标。
The desired output (figure 3)
问题：我在列表视图中显示共享首选项中的图像时遇到问题。
以下代码块来自CustomListAdapter ::
public class CustomListAdapter extends ArrayAdapter {
private final Activity context;
private final String[] infoArray;
List<Object> selectlist = new ArrayList<Object>();
public static final String PREFERENCE_NAME = "favourite";
private final SharedPreferences sharedpreferences;
List<Object> favourites;
int[] image;
public CustomListAdapter(Activity context,String[] infoArrayParam,int[] imageIds){
super(context,R.layout.listview_row,infoArrayParam);
this.context=context;
this.infoArray = infoArrayParam;
this.image = imageIds;
sharedpreferences = context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE);
}
public View getView(final int position,View view,ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
final View rowView = inflater.inflate(R.layout.listview_row,parent,false);
TextView nameTextField = (TextView) rowView.findViewById(R.id.textView2);
final ImageView imageView = (ImageView) rowView.findViewById(R.id.imageView4);
imageView.setOnClickListener(new View.OnClickListener(){
@SuppressLint({"NewApi","ResourceType"})
@Override
public void onClick(View view) {
view.setSelected(!view.isSelected());
boolean favSelected = view.isSelected();
if (favSelected) {
imageView.setImageResource(R.drawable.ic_baseline_favorite1_24);
imageView.setTag(position);
imageView.setId(R.drawable.ic_baseline_favorite1_24);
Object chk = infoArray[position];
selectlist.add(chk);
view.setSelected(true);
saveData(context,selectlist);
}
else{
imageView.setImageResource(R.drawable.ic_baseline_favorite_border_24 );
imageView.setTag(position);
imageView.setId(R.drawable.ic_baseline_favorite_border_24);
view.setSelected(false);
removeFavorite(context,selectlist);
}
}
private boolean saveData(Context context,List<Object> selectlist){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getContext());
SharedPreferences.Editor aSharedPreferencesEdit = sharedPreferences.edit();
Gson gson = new Gson();
String json = gson.toJson(selectlist);
aSharedPreferencesEdit.putString("task list",json);
aSharedPreferencesEdit.apply();
return false;
}
private ArrayList<Object> loadData(Context context){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getContext());
Gson gson = new Gson();
String json = sharedPreferences.getString("task list",null);
System.out.println("The value of jsonnnnnnnn is " + json);
Type type = new TypeToken<List<Object>>(){}.getType();
System.out.println("The value of typpppppppppe is " + type);
return gson.fromJson(json,type);
}
public void removeFavorite(Context context,List<Object> selectlist) {
ArrayList<Object> favourites = loadData(context);
if (favourites != null) {
favourites.remove(selectlist);
saveData(context,favourites);
}
}
private boolean favOnClick(int position,View v,List<Object> selectlist){
ImageView button = (ImageView) v.findViewById(R.id.imageView4);
String tag = button.getTag().toString();
if (tag.equalsIgnoreCase(valueOf(position))){
saveData(context,selectlist);
button.setTag(position);
button.setImageResource(R.drawable.ic_baseline_favorite1_24);
}
else {
removeFavorite(context,selectlist);
button.setTag(position);
button.setImageResource(R.drawable.ic_baseline_favorite_border_24);
}
return true;
}
});
nameTextField.setText(infoArray[position]);
imageView.setImageResource(image[position]);
return rowView;
}
}
以下代码块用于DashBoard：
public class DashBoard extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {
ListView listView;
Toolbar mActionBarToolBar;
Context context;
List<Object> selectlist ;
private ArrayAdapter<Object> adapter;
int[] drawableIds = new int[]{R.drawable.ic_baseline_favorite1_24,R.drawable.ic_baseline_favorite_border_24};
String[] infoArray = {
//Listed
};
protected void onCreate(Bundle savedInstanceState) {
SharedPreferences sharedPreferences = getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE);
CustomListAdapter listItems = new CustomListAdapter(this,infoArray,drawableIds);
listView = (ListView) findViewById(R.id.listviewId);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView,int position,long id) {
//To do
}
});
listView.setAdapter(listItems);
}
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
int id = item.getItemId();
switch (id) {
case R.id.navigation_notifications:
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
Gson gson = new Gson();
String json = sharedPreferences.getString("task list",null);
System.out.println("The value of jsonnnnnnnn is " + json);
Type type = new TypeToken<List<Object>>(){}.getType();
System.out.println("The value of typpppppppppe is " + type);
selectlist = gson.fromJson(json,type);
if (selectlist == null){
selectlist= new ArrayList<>();
}
adapter = new ArrayAdapter<Object>(DashBoard.this,android.R.layout.simple_list_item_1,(selectlist));
listView.setAdapter(adapter);
}
return false;
}
}
参考： How to save dynamically added items in Listview with sharedpreferences?
任何帮助将不胜感激。
谢谢。
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