如何在從活動類填充ListView的非活動類中正確設置setOnItemClickListener

Question

我的ListView是根據用戶在非活動類中輸入EditText的內容從HashMap動態創建的。 我之所以認為它與setOnItemClickListener有關，是因為當我在OnCreate方法的Activity類中手動設置ListView值時，它可以工作。 非活動類包含用於AsyncTask和遞歸方法的幾個方法。

活動課

public class WordEntry extends AppCompatActivity implements OnClickListener, OnItemClickListener {

//Variable's Declared

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

    /*Code for reading values into HashMap here*/

    btn_Resolve = (Button) findViewById(R.id.submit_word);
    btn_Resolve.setOnClickListener(this);

    //TODO Make list item's clickable.

    spin_options = (Spinner) findViewById(R.id.spin_choose_resolver_type);
    ArrayAdapter<CharSequence> spin_adapter = ArrayAdapter.createFromResource(this,
            R.array.resolver_options, R.layout.simpler_spinner_item);

    spin_adapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
    spin_options.setAdapter(spin_adapter);
    lv_words = (ListView) findViewById(R.id.lv_word_display);

    /*This following two lines were a test to see if manually setting the adapter worked, it did. */
    //lv_words.setAdapter(spin_adapter);
    //lv_words.setOnItemClickListener(this);


}

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

    Log.i("HelloListView", "You clicked item: " + parent + " at position: " + position);

}


@Override
public void onClick(View v) {

    switch (v.getId()) {
        case R.id.submit_word:

            edt_WordEntry = (EditText) findViewById(R.id.word_entry_textbox);
            word = edt_WordEntry.getText().toString().toLowerCase();
            Pattern pattern = Pattern.compile("\\s");
            Matcher matcher = pattern.matcher(word);
            boolean space_found = matcher.find();
            View hideKey = this.getCurrentFocus();

            if (space_found) {
               edt_WordEntry.setText(R.string.no_spaces_allowed);

            } else {
                ResolveWord fixAnagram = new ResolveWord(word, this,wordHashSet);
                ResolveAllWords fixAnagramAll = new ResolveAllWords(word,this,wordHashSet);

                /*The following two lines are two other methods that I tried during debugging to try get it working. Separately of                  course and this debugging was for when the spinner was set to something other than "Anagram's"*/
                //fixAnagramAll.lv_words.setOnItemClickListener(new ResolveWord(word,this,wordHashSet));  
                //lv_words.setOnItemClickListener(new ResolveWord(word,this,wordHashSet));                           
                if(spin_options.getSelectedItem().toString().equals("Anagram;s")) {
                    hideKeyboard(this);
                    fixAnagram.execute();
                } else {
                    hideKeyboard(this);
                    fixAnagramAll.execute();
                }
            }
            break;

        default:
            break;
    }

}

非活動班

public class ResolveWord extends  AsyncTask<Void, Integer, ArrayList<String>> implements OnItemClickListener {

 /*Variable's Declared*/


public ResolveWord(String letters, Activity wordEntryContext, HashSet<String> passedHashSet) {
    /*Variables initiated */

}


   /*Some code.....*/

@Override
protected void onPostExecute(ArrayList<String> wordSuccess) {

    /*Code which puts data into an arraylist so I can put into the array adadater that follows...*/

    ArrayAdapter<String> adapter = new ArrayAdapter<>(thisContext,R.layout.lv_displaywrods_wordentry,
            wordSuccess);

    //Ways I tried to get the ListView clickable in the non-activity class...
    lv_words.setAdapter(adapter);

    //lv_words.setOnItemClickListener(new WordEntry());
    //lv_words.setOnItemClickListener(this);

   /*lv_words.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        //I have a break point here to see if the string gets assigned during debugging after clicking a rowitem.
        String x = "Test";

    }
});*/

    //This always returns false
    boolean o = lv_words.hasOnClickListeners();
    //This always returns true
    boolean p = lv_words.isClickable();


}

在上面的代碼之上，我不久前還以為我解決了它，並在onCreate方法的活動類中創建了onItemClickListener並使用getOnItemClickListener分配了一個值，不久前我也進行了一些編輯。 然后，我通過構造函數將其傳遞給非活動類，但這也無法正常工作。

Answer 1

在AsyncTask可以設置OnClickListeners在onPostExecute方法之一onPreExecute方法。
您不能在doInBackground方法中添加OnClickListener或執行任何UI操作，因為您正在執行網絡操作。

因此，您可以設置OnClickListener regullary：

lv_words.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick() {
        // Do some coding...
    }
});

Answer 2

在幕后，ArrayAdapter使用提供給它的ArrayList（或數組）中每個條目的toString（）方法，並填充在您使用的構造函數的第二個參數中指定的布局。

如果wordSuccess數組列表不為空，則該條目到此布局的映射失敗。 ArrayAdapter希望將TextView或其派生類作為該構造函數中的第二個參數。 您的lv_displaywords_wordentry布局文件可能不是簡單的TextView，或者它包含用某種ViewGroup容器包裝的TextView。 由於您顯示的是簡單列表項，因此建議您使用android.R.layout.simple_list_item_1，如果數組列表不為空，則應該會看到顯示的單詞。

編輯：

就像我猜到的那樣，從注釋中可以理解，您正在嘗試將解析為布局的布局傳遞給ArrayAdapter中的ListView而不是TextView。 您可以正常使用ListView，但是適配器無法將數組列表中的String條目映射到ListView對象（因為ListView代表整個集合，而映射是一對一進行的）。 這就是為什么您需要傳遞TextView（或其自定義子類或它的變體）的原因。 使用android提供的列表項布局，您應該獲得標准的TextView。

Answer 3

您可以嘗試為ResolveWord設置傳承程序，以將WordEntry對象-wordEntry傳遞給ResolveWord，然后在onPostExecute（...）中編寫： lv_words.setOnItemClickListener（wordEntry）;

Answer 4

很難理解您，但是我認為您將要存檔以下內容：

public class ResolveWord extends  AsyncTask<Void, Integer, ArrayList<String>> {
    private Activity wordEntryContext;

   public ResolveWord(String letters, Activity wordEntryContext, HashSet<String> passedHashSet) {
       this.wordEntryContext = wordEntryContext;
       /*Other variables initiated */ 
   } 

   @Override 
   protected void onPostExecute(ArrayList<String> wordSuccess) {
       // your code
       lv_words.setOnItemClickListener((OnItemClickListener)wordEntryContext); 
   }

}