android - 将复选框的选中状态保存在多选 ListView 中

我是这个多重选择列表视图的新手。我想将复选框的选中状态保存在列表视图中，以便如果用户关闭应用程序然后再次打开，则选中的复选框仍保持选中状态。有什么办法可以做到这一点。我搜索了它，发现可以使用SharedPreference完成它，但是我没有获得有关如何使用它的更多信息。谢谢

public class MainActivity extends AppCompatActivity {

    ListView myList;
    Button getChoice;

    String[] listContent = {

            "January",
            "February",
            "March",
            "April",
            "May",
            "June",
            "July",
            "August",
            "September",
            "October",
            "November",
            "December"

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        myList = (ListView)findViewById(R.id.list);
        getChoice = (Button)findViewById(R.id.getchoice);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_multiple_choice, listContent);
        myList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

        myList.setAdapter(adapter);

        getChoice.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String selected = "";
                int cntChoice = myList.getCount();

                SparseBooleanArray sparseBooleanArray = myList.getCheckedItemPositions();
                for(int i = 0; i < cntChoice; i++){
                    if(sparseBooleanArray.get(i)) {
                        selected += myList.getItemAtPosition(i).toString() + "\n";

                    }

                }

                Toast.makeText(MainActivity.this, selected, Toast.LENGTH_LONG).show();

            }
        });



    }
}

最佳答案

您可以例如在SharedPreferences中保存状态。

因此，您的onCreate和onDestroy方法将类似于：

SharedPreferences sharedPreferences = getSharedPreferences("MySharedPrefs", MODE_PRIVATE);

@Override
protected void onCreate(final Bundle savedInstanceState) {
    ...
    Set<String> checkedItemsSource = sharedPreferences.getStringSet("checked_items", new HashSet<String>());
    SparseBooleanArray checkedItems = convertToCheckedItems(checkedItemsSource);
    for (int i = 0; i < checkedItems.size(); i++) {
        int checkedPosition = checkedItems.keyAt(i);
        listView.setItemChecked(checkedPosition, true);
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
    SparseBooleanArray checkedItems = listView.getCheckedItemPositions();
    Set<String> stringSet = convertToStringSet(checkedItems);
    sharedPreferences.edit()
            .putStringSet("checked_items", stringSet)
            .apply();
}

private SparseBooleanArray convertToCheckedItems(Set<String> checkedItems) {
    SparseBooleanArray array = new SparseBooleanArray();
    for(String itemPositionStr : checkedItems) {
        int position = Integer.parseInt(itemPositionStr);
        array.put(position, true);
    }

    return array;
}

private Set<String> convertToStringSet(SparseBooleanArray checkedItems) {
    Set<String> result = new HashSet<>();
    for (int i = 0; i < checkedItems.size(); i++) {
        result.add(String.valueOf(checkedItems.keyAt(i)));
    }

    return result;
}