我正在编一本字典。但搜寻没有成功。这里我使用的是SQLite数据库。当我运行该应用程序时，没有出现错误通知。我不明白我哪里错了。其他菜单都可以，只有搜索不行。当我输入这个词时，什么也没有出现。
这是针对MainActivity.java的
import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.view.GravityCompat;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import com.google.android.material.navigation.NavigationView;
import java.util.ArrayList;
public class kamusActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
MenuItem menuSetting;
Toolbar toolbar;
DBHelper dbHelper;
EditText edit_search;
DictionaryFragment dictionaryFragment;
BookmarkFragment bookmarkFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_kamus);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
dbHelper = new DBHelper(this);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener((NavigationView.OnNavigationItemSelectedListener) this);
dictionaryFragment = new DictionaryFragment();
bookmarkFragment = BookmarkFragment.getNewInstance(dbHelper);
goToFragment(dictionaryFragment, true);
dictionaryFragment.setOnFragmentListener(new FragmentListener() {
@Override
public void onItemClick(String value) {
String id = Bahasa.getState(kamusActivity.this,"dic_type");
int dicType = id == null? R.id.action_it:Integer.valueOf(id);
goToFragment( DetailFragment.getNewInstance(value,dbHelper,dicType),false);
}
});
bookmarkFragment.setOnFragmentListener(new FragmentListener() {
@Override
public void onItemClick(String value) {
String id = Bahasa.getState(kamusActivity.this,"dic_type");
int dicType = id == null? R.id.action_it:Integer.valueOf(id);
goToFragment( DetailFragment.getNewInstance(value,dbHelper,dicType),false);
}
});
edit_search = findViewById(R.id.edit_search);
edit_search.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2){
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2){
dictionaryFragment.filterValue(charSequence.toString());
}
@Override
public void afterTextChanged(Editable editable){
}
});
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
}else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
// Inflate the menu; this adds items to the action bar if it is present
getMenuInflater().inflate(R.menu.main_menu, menu);
menuSetting = (MenuItem) menu.findItem(R.id.action_settings);
String id = Bahasa.getState(this,"dic_type");
if (id != null)
onOptionsItemSelected(menu.findItem(Integer.valueOf(id)));
else {
ArrayList<String> source = dbHelper.getWord(R.id.action_it);
dictionaryFragment.resetDataSource(source);
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if(R.id.action_settings == id)return true;
//noinspection SimplifiableIfStatement
if (id == R.id.action_it) {
Bahasa.saveState(this,"dic_type", String.valueOf(id));
ArrayList<String> source = dbHelper.getWord(id);
dictionaryFragment.resetDataSource(source);
menuSetting.setIcon(getDrawable(R.drawable.icon_bibt_2));
return true;
}else if (id == R.id.action_ti){
Bahasa.saveState(this,"dic_type", String.valueOf(id));
ArrayList<String> source = dbHelper.getWord(id);
dictionaryFragment.resetDataSource(source);
menuSetting.setIcon(getDrawable(R.drawable.icon_btbi_2));
return true;
}
return super.onOptionsItemSelected(item);
}
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_bookmark){
String activeFragment = getSupportFragmentManager().findFragmentById(R.id.fragment_container).getClass().getSimpleName();
if(!activeFragment.equals(BookmarkFragment.class.getSimpleName())){
goToFragment(bookmarkFragment, false);
}
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
void goToFragment(Fragment fragment, boolean isTop){
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
if (!isTop)
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
String activeFragment = getSupportFragmentManager().findFragmentById(R.id.fragment_container).getClass().getSimpleName();
if (activeFragment.equals(BookmarkFragment.class.getSimpleName())){
menuSetting.setVisible(false);
toolbar.findViewById(R.id.edit_search).setVisibility(View.GONE);
toolbar.setTitle("Bookmark");
}else {
menuSetting.setVisible(true);
toolbar.findViewById(R.id.edit_search).setVisibility(View.VISIBLE);
toolbar.setTitle("");
}
return true;
}
}
这是我的片段字典的源代码
字典片段.java
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import java.util.ArrayList;
public class DictionaryFragment extends Fragment {
private String value = "Hello everyone!!!";
private FragmentListener listener;
ArrayAdapter<String> adapter;
ListView dicList;
private ArrayList<String> mSource = new ArrayList<>();
public DictionaryFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_dictionary, container, false);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
dicList = view.findViewById(R.id.dictionaryList);
adapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_1,mSource);
dicList.setAdapter(adapter);
dicList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
if (listener != null)
listener.onItemClick(mSource.get(position));
}
});
}
public void resetDataSource(ArrayList<String> source){
mSource = source;
adapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_1,mSource);
dicList.setAdapter(adapter);
}
public void filterValue(String value){
// adapter.getFilter().filter(value); int size = adapter.getCount(); for (int i = 0 ; i<size;i++){ if (adapter.getItem(i).startsWith(value)){ dicList.setSelection(i); break; } } }
public void setOnFragmentListener(FragmentListener listener){
this.listener = listener;
}
}
使用 ViewModel 从 Activity 传递数据
public class MyViewModel extends ViewModel {
private final MutableLiveData<String> realtimedata = new MutableLiveData<>();
public LiveData<String> getSensorData() {
return realtimedata;
}
public void update(String data) {
realtimedata.setValue(data);
}
}
观察 ViewModel WithIn Fragment 来获取 SearchData：
private MyViewModel myViewModel;
myViewModel = ViewModelProviders.of(this).get(MyViewModel::class.java)
myViewModel.getSensorData().observe(viewLifecycleOwner, Observer<String> { data ->
// Update the UI
})