实现标签功能，例如Instagram

Question

在此演示中，我想添加诸如Instagram之类的标签功能。当我使用@搜索追随者时，其工作正确并显示该追随者的名称。但是，当我在搜索中删除@时，它会显示错误。java.lang.StringIndexOutOfBoundsException: length=0; index=1.我使用许多代码，但不解决。需要帮助代码在这里： -

public class Main2Activity extends AppCompatActivity {
    RecyclerView following_userr_list, mListView_COmment;
    EditText editTextSearch;
    ArrayList<String> FollowingListValuesArr;
    ArrayList<String> show_following;
    CustomAdapter adapter;
    Custom_comment_Adapter adapter1;
    String final_string = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        FollowingListValuesArr = new ArrayList<>();
        FollowingListValuesArr.add("Ramiz");
        FollowingListValuesArr.add("Karan");
        FollowingListValuesArr.add("Azad");
        FollowingListValuesArr.add("Manish");
        show_following = new ArrayList<>();
        show_following.add("Ramiz");
        show_following.add("Karan");
        show_following.add("Azad");
        show_following.add("Manish");
        following_userr_list = (RecyclerView) findViewById(recyclerView);
        editTextSearch = (EditText) findViewById(R.id.editTextSearch);
        mListView_COmment = (RecyclerView) findViewById(recyclerView_comment);

        following_userr_list.setHasFixedSize(true);
        following_userr_list.setLayoutManager(new LinearLayoutManager(this));
        mListView_COmment.setHasFixedSize(true);
        mListView_COmment.setLayoutManager(new LinearLayoutManager(this));
        adapter = new CustomAdapter(FollowingListValuesArr);
        adapter1 = new Custom_comment_Adapter(show_following);
        following_userr_list.setAdapter(adapter);
        mListView_COmment.setAdapter(adapter1);
        editTextSearch.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            }
            @Override
            public void onTextChanged(CharSequence s, int i, int i1, int count) {

            }
            @Override
            public void afterTextChanged(Editable editable) {

                String s = editable.toString();
                final_string = s.substring(1);
                if (final_string.length() >= 1) {
                    following_userr_list.setVisibility(View.INVISIBLE);
                    mListView_COmment.setVisibility(View.VISIBLE);
                    filters(final_string);
                }
            }

            private void filters(String text) {
                ArrayList<String> filterdNames = new ArrayList<>();

                for (String s : FollowingListValuesArr) {
                    if (s.toLowerCase().contains(text.toLowerCase())) {
                        filterdNames.add(s);
                    }
                }
                adapter.filterList(filterdNames);
                adapter1.filterList(filterdNames);
            }
        });
    }
}

Answer 1

您在此功能中遇到错误。您需要在处理之前检查可编辑的长度。

@Override
            public void afterTextChanged(Editable editable) {

                String s = editable.toString();
                final_string = s.substring(1);// when s is null 
                if (final_string.length() >= 1) {
                    following_userr_list.setVisibility(View.INVISIBLE);
                    mListView_COmment.setVisibility(View.VISIBLE);
                    filters(final_string);
                }
            }

当字符串为null时，您正在执行s.substring

所以添加如下

            @Override
            public void afterTextChanged(Editable editable) {
               if (editable.length() > 0) {
                String s = editable.toString();
                final_string = s.substring(1);

                    following_userr_list.setVisibility(View.INVISIBLE);
                    mListView_COmment.setVisibility(View.VISIBLE);
                    filters(final_string);
                }
            }

Answer 2

我认为您应该在逻辑之前检查长度。

    @Override
    public void afterTextChanged(Editable editable) {
        if(editable.length()>0){
            String s = editable.toString();
            final_string = s.substring(1);
            if (final_string.length() >= 1) {
                following_userr_list.setVisibility(View.INVISIBLE);
                mListView_COmment.setVisibility(View.VISIBLE);
                filters(final_string);
            }
         }
    }