Question

我有一个单独运行的ListView，但由于某些原因添加搜索栏似乎毁了一切。我可以打开ListView并单击某个项目以进入新页面，但是按一个键键入搜索栏会导致“不幸的是，myapp已停止”。我从logcat得到一个NullPointerException，但我没做什么似乎解决了。任何帮助将不胜感激！

listview活动：

public class SecondScreenActivity extends Activity
{

    // Listview Adapter
    ArrayAdapter<String> arrayAdapter;

    // Search EditText
    EditText inputSearch;

        ArrayList<String> RecipeList;
        public void onCreate(Bundle saveInstanceState)
        {
                super.onCreate(saveInstanceState);
                setContentView(R.layout.main);

               // Get the reference of ListViewRecipes
                ListView RecipeListView=(ListView)findViewById(R.id.mainListView);

                 RecipeList = new ArrayList<String>();
                 getRecipeNames();

                 RecipeListView = (ListView) findViewById(R.id.mainListView);
                 inputSearch = (EditText) findViewById(R.id.inputSearch);

                 // Adding items to listview
                 ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, RecipeList); 
     //^^^this is the line that seems to be the problem^^^

                 // Set The Adapter
                 RecipeListView.setAdapter(arrayAdapter);


                 //Search
                 inputSearch = (EditText) findViewById(R.id.inputSearch);
                 /**
                  * Enabling Search Filter
                  * */
                 inputSearch.addTextChangedListener(new TextWatcher() {

       @Override
       public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
       // When user changes the Text
       SecondScreenActivity.this.arrayAdapter.getFilter().filter(cs);   
       }

       @Override
       public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                             int arg3) {
       // TODO Auto-generated method stub

       }

       @Override
       public void afterTextChanged(Editable arg0) {
       // TODO Auto-generated method stub                          
       }
       });

       // register onClickListener to handle click events on each item
       RecipeListView.setOnItemClickListener(new OnItemClickListener()
       {
           public void onItemClick(AdapterView<?> parent, View itemClicked,
                            int position, long id) {

           TextView textView = (TextView) itemClicked;
           String strText = textView.getText().toString();

           Intent intenttwo = new Intent(SecondScreenActivity.this, ThirdScreenActivity.class);
           intenttwo.putExtra("position", strText);
           startActivity(intenttwo);
           }
           });

        }

        void getRecipeNames()
        {
            RecipeList.add("Recipe1");
            RecipeList.add("Recipe2");
            RecipeList.add("Recipe3");
            RecipeList.add("Recipe4");
            RecipeList.add("Recipe5");
            RecipeList.add("Recipe6");
            RecipeList.add("Recipe7");
            RecipeList.add("Recipe8");
            RecipeList.add("Recipe9");
            RecipeList.add("Recipe10");

        }  
}

修改这是一个略微修改的listview活动。这使得搜索栏工作，但是当单击ListView中的项目时，应用程序被强制关闭，并出现logcat错误： java.lang.classcastexception：android.widget.linearlayout无法强制转换为android.widget.textview < / strong>即可。这可能有所帮助，可能不会！

import java.util.ArrayList; import java.util.HashMap; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.EditText; import android.widget.ListView; import android.widget.AdapterView.OnItemClickListener; import android.text.Editable; import android.text.TextWatcher; import android.view.View; public class SecondScreenActivity extends Activity { // List view private ListView lv; // Listview Adapter ArrayAdapter<String> adapter; // Search EditText EditText inputSearch; // ArrayList for Listview ArrayList<HashMap<String, String>> recipeList; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // Listview Data String recipes[] = {"Recipe1", "Recipe2", "Recipe3", "Recipe4", "Recipe5", "Recipe6", "Recipe7", "Recipe8", "Recipe9", "Recipe10"}; lv = (ListView) findViewById(R.id.mainListView); inputSearch = (EditText) findViewById(R.id.inputSearch); // Adding items to listview adapter = new ArrayAdapter<String>(this, R.layout.list_item, R.id.recipe_name, recipes); lv.setAdapter(adapter); // Enabling search filter inputSearch.addTextChangedListener(new TextWatcher() { @Override public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) { // When user changed the Text SecondScreenActivity.this.adapter.getFilter().filter(cs); } @Override public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) { // TODO Auto-generated method stub } @Override public void afterTextChanged(Editable arg0) { // TODO Auto-generated method stub } }); // register onClickListener to handle click events on each item lv.setOnItemClickListener(new OnItemClickListener() { // argument position gives the index of item which is clicked public void onItemClick(AdapterView<?> parent, View itemClicked, int position, long id) { //TO DO: Send string (position) of recipe name // TextView textView = (TextView) findViewById(itemClicked); // String stringName = textView.getText().toString(); String stringName = (String) (lv.getItemAtPosition(position)); Intent intenttwo = new Intent(SecondScreenActivity.this, ThirdScreenActivity.class); intenttwo.putExtra("position", stringName); startActivity(intenttwo); } }); } }

我的logcat（使用第一个活动时）：

06-25 22:37:54.353: E/AndroidRuntime(4646): FATAL EXCEPTION: main 06-25 22:37:54.353: E/AndroidRuntime(4646): java.lang.NullPointerException 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.example.myapp.SecondScreenActivity$1.onTextChanged(SecondScreenActivity.java:66) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.widget.TextView.sendOnTextChanged(TextView.java:7231) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.widget.TextView.handleTextChanged(TextView.java:7290) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:8880) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:962) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:496) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:435) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:30) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.method.QwertyKeyListener.onKeyDown(QwertyKeyListener.java:222) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.text.method.TextKeyListener.onKeyDown(TextKeyListener.java:136) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.widget.TextView.doKeyDown(TextView.java:5385) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.widget.TextView.onKeyDown(TextView.java:5204) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.KeyEvent.dispatch(KeyEvent.java:2609) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.View.dispatchKeyEvent(View.java:7205) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359) 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1920) 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1395) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.app.Activity.dispatchKeyEvent(Activity.java:2370) 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1847) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewRootImpl.deliverKeyEventPostIme(ViewRootImpl.java:3701) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewRootImpl.handleImeFinishedEvent(ViewRootImpl.java:3651) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:2818) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.os.Handler.dispatchMessage(Handler.java:99) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.os.Looper.loop(Looper.java:137) 06-25 22:37:54.353: E/AndroidRuntime(4646): at android.app.ActivityThread.main(ActivityThread.java:5041) 06-25 22:37:54.353: E/AndroidRuntime(4646): at java.lang.reflect.Method.invokeNative(Native Method) 06-25 22:37:54.353: E/AndroidRuntime(4646): at java.lang.reflect.Method.invoke(Method.java:511) 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 06-25 22:37:54.353: E/AndroidRuntime(4646): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 06-25 22:37:54.353: E/AndroidRuntime(4646): at dalvik.system.NativeStart.main(Native Method)

感谢您的帮助！

Answer 1

This answer应该对你有帮助，它有一个很好的例子。我相信如果您使用的getFilter()看起来不像您，则需要覆盖适配器中的Custom Adapter方法。

在这种情况下，您可以使用setOnQueryTextListener并实现类似

的内容

searchField = (SearchView) findViewById(R.id.search_plate);
    searchField.setOnQueryTextListener(new SearchView.OnQueryTextListener() {

        @Override
        public boolean onQueryTextSubmit(String query) {
            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {
            // search goes here !!
            setFilters("searchtext", newText);

            return false;
        }
    });

其中setFilters()是您定义的函数。这是一个关于我的变量的例子，你的变量会有所不同。

您可能还会发现this answer和this one有用。我希望这有帮助

SearchView Docs

搜索栏与列表视图

1 个答案: