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？我试图转换arraylist到array和retriving.代码仍无效.

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

也许以下内容对您有帮助.

arraylistname.get(position);

Answer 2

我的理解你的问题是你想ArrayList在一个特定的位置获取一个元素.

假设您的列表包含整数1,2,3,4,5并且您想要获取值3.然后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
        }

您可以使用哪种方式 list.get(list.lastIndexOf(3))

Answer 3

在 arraylist 中，您有位置顺序而不是名义顺序，因此您需要提前知道需要选择的元素位置，或者必须在元素之间循环，直到找到需要使用的元素。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());
}