从Android中的数组列表中检索元素？

Question

我正在尝试在 Android 中实现语音识别代码。如何从Android中的数组列表中获取特定位置的元素？我尝试将arraylist 转换为array 并进行检索。代码仍然不起作用。

package com.espeaker;


    public class EspeakerActivity extends Activity {

                    private static final int REQUEST_CODE = 1234;
            private ListView wordsList;


            /** Called when the activity is first created. */
            @Override
            public void onCreate(Bundle savedInstanceState) {
                  super.onCreate(savedInstanceState);
                  setContentView(R.layout.main);


                  Button speakButton = (Button) findViewById(R.id.speakButton);

                  wordsList = (ListView) findViewById(R.id.list);

                  // Disable button if no recognition service is present
                  PackageManager pm = getPackageManager();
                  List<ResolveInfo> activities = pm.queryIntentActivities(
                          new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
                  if (activities.size() == 0)
                  {
                      speakButton.setEnabled(false);
                      speakButton.setText("Recognizer not present");
                  }
            }

    /**
     * Handle the action of the button being clicked
     */
    public void speakButtonClicked(View v)
    {
        startVoiceRecognitionActivity();
    }

    /**
     * Fire an intent to start the voice recognition activity.
     */
    private void startVoiceRecognitionActivity()
    {
        Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
                RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
        intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Voice recognition Demo...");
        startActivityForResult(intent, REQUEST_CODE);
    }

    /**
     * Handle the results from the voice recognition activity.
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if (requestCode == REQUEST_CODE && resultCode == RESULT_OK)
        {
            // Populate the wordsList with the String values the recognition engine thought it heard
            ArrayList<String> matches = data.getStringArrayListExtra(
                    RecognizerIntent.EXTRA_RESULTS);
            wordsList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
                    matches));
            String[] array=matches.toArray(new String[matches.size()]);
           // ArrayList<String> places = new ArrayList<String>(
                //    Arrays.asList("black", "blue", "red"));
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item,matches);
              final AutoCompleteTextView input_text = (AutoCompleteTextView) findViewById(R.id.auto);
              Button button1 = (Button) findViewById(R.id.button1);
                     input_text.setAdapter(adapter);
            button1.setText(" "+array[0]);

           // button1.setText(""+matches);
             }
        super.onActivityResult(requestCode, resultCode, data);
    }
    }

Answer 1

在arraylist中你有一个位置顺序而不是名义顺序，所以你需要提前知道你需要选择的元素位置或者你必须在元素之间循环直到你找到你需要使用的元素。为此，您可以使用迭代器和 if，例如：

Iterator iter = list.iterator();
while (iter.hasNext())
{
    // if here          
    System.out.println("string " + iter.next());
}

Answer 2

public class DemoActivity extends Activity {
    /** Called when the activity is first created. */
    ArrayList<String> al = new ArrayList<String>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);



        // add elements to the array list

        al.add("C");
        al.add("A");
        al.add("E");
        al.add("B");
        al.add("D");
        al.add("F");

        // retrieve elements from array

        String data = al.get(pass the index here);
        System.out.println("Data is "+ data);

这是另一种获取元素的方式

        Iterator<String> it = al.iterator();
        while (it.hasNext()) {
            System.out.println("Data is "+ it.next());
        }
    }

Answer 3

我理解您的问题是您想在特定位置获取 ArrayList 中的元素。

假设您的列表包含整数 1,2,3,4,5，并且您想要获取值 3。那么以下代码行将起作用。

ArrayList<Integer> list = new ArrayList<Integer>();
        if(list.contains(3)){//check if the list contains the element
            list.get(list.indexOf(3));//get the element by passing the index of the element
        }

您可以通过任何方式使用list.get(list.lastIndexOf(3))

Answer 4

也许以下内容对您有所帮助。

arraylistname.get(position);

Answer 5

你不能试试这个

for (WordList i : words) {
     words.get(words.indexOf(i));
 }

Answer 6

我有一个要检索的数组位置列表，这对我有用。

  public void create_list_to_add_group(ArrayList<Integer> arrayList_loc) {
     //In my case arraylist_loc is the list of positions to retrive from 
    // contact_names 
    //arraylist and phone_number arraylist

    ArrayList<String> group_members_list = new ArrayList<>();
    ArrayList<String> group_members_phone_list = new ArrayList<>();

    int size = arrayList_loc.size();

    for (int i = 0; i < size; i++) {

        try {

            int loc = arrayList_loc.get(i);
            group_members_list.add(contact_names_list.get(loc));
            group_members_phone_list.add(phone_num_list.get(loc));


        } catch (Exception e) {
            e.printStackTrace();
        }


    }

    Log.e("Group memnbers list", " " + group_members_list);
    Log.e("Group memnbers num list", " " + group_members_phone_list);

}