android - インスタンス化できず、OnActivityResult に関する質問

Question

public class MainActivity extends Activity {

private static final int GET_MOVIE = 1000;
private Button btn1;
String movie;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn1 = (Button) findViewById(R.id.button1);
    movie = btn1.getText().toString();

    Log.e("kjw", "outlistener_main");
    btn1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {



            Intent i = new Intent(getApplicationContext(), MovieActivity.class);
            i.putExtra("movie", movie);

            startActivityForResult(i, GET_MOVIE);


        }
    });
}

public void OnActivityResult(int requestCode, int resultCode, Intent data) {

    if(requestCode == GET_MOVIE && resultCode == RESULT_OK) {
    movie = data.getExtras().getString("return");
    btn1.setText(movie);
    }

    super.onActivityResult(requestCode, resultCode, data);


}

}

public class MovieActivity extends ListActivity {

private ProgressDialog pDialog;

// URL to get contacts JSON

private String url = "http://www.kobis.or.kr/kobisopenapi/webservice/rest/boxoffice/searchDailyBoxOfficeList.json?key=165fd244a33a11b50938eacd1fcbe6aa&targetDt=20140107";

Calendar calendar = Calendar.getInstance();
String curY = String.valueOf(calendar.get(Calendar.YEAR));
String curM = String.valueOf(calendar.get(Calendar.MONTH) + 1);
String curD = String.valueOf(calendar.get(Calendar.DATE) - 1);
String day = curY + curM + curD;

// JSON Node names
private static final String TAG_BOXOFFICERESULT = "boxOfficeResult";
private static final String TAG_DAILYBOXOFFICELIST = "dailyBoxOfficeList";
private static final String TAG_RNUM = "rnum";
private static final String TAG_MOVIENM = "movieNm";
private static final String TAG_OPENDT = "openDt";

// contacts JSONArray
JSONArray movies = null;

// Hashmap for ListView
ArrayList<HashMap<String, String> > movieList;

TextView t;
String movie;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Log.d("Response", ">" + "a" );
    setContentView(R.layout.activity_movie);

    Log.d("Response", ">" + "b" );

    movieList = new ArrayList<HashMap<String, String>>();

    Log.d("Response", ">" + "c" );

    // Calling async task to get json
    new GetContacts().execute();

    Log.d("Response", ">" + "d" );

    t = (TextView) findViewById(R.id.movienm);
    movie = t.getText().toString();
    ListView lv = (ListView) findViewById(android.R.id.list);
    Log.e("kjw", "outlistener");

    lv.setOnItemClickListener(new OnItemClickListener() {


        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {

            Intent i = getIntent();
            movie = i.getStringExtra("movie");
            i.putExtra("return", movie);
            setResult(RESULT_OK, i);
            finish();               
        }

    });


}

/**
 * Async task class to get json by making HTTP call
 * */
private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(MovieActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(Void... arg0) {
        // Creating service handler class instance
        ServiceHandler sh = new ServiceHandler();

        Log.d("Response", ">" + "1" );

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);

        Log.d("Response", ">" + "2" );


        if (jsonStr != null) {

            Log.d("Response", ">" + "22" );


            try {
                Log.d("Response", ">" + "222" );
                JSONObject jsonObj = new JSONObject(jsonStr);
                Log.d("Response", ">" + "2222" );


                JSONObject a = jsonObj.getJSONObject(TAG_BOXOFFICERESULT);
                Log.d("Response", ">" + "22222" );


                movies = a.getJSONArray(TAG_DAILYBOXOFFICELIST);

                for (int i=0; i <movies.length(); i++) {

                    Log.d("Response", ">" + "222222" );

                    JSONObject c  = movies.getJSONObject(i);
                    String rnum = c.getString(TAG_RNUM);
                    String movienm = c.getString(TAG_MOVIENM);
                    String opendt = c.getString(TAG_OPENDT);

                    // tmp hashmap for single contact
                    HashMap<String, String> movie = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    movie.put(TAG_RNUM, rnum);
                    movie.put(TAG_OPENDT, opendt);
                    movie.put(TAG_MOVIENM, movienm);

                    Log.d("Response", ">" + "2222222" );
                    // adding contact to contact list
                    movieList.add(movie);
                    Log.d("Response", ">" + "2222222222" );
                }


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

                Log.d("Response: ", "> " + "2b");
            }
        } else {
            Log.e("ServiceHandler", "Couldn't get any data from the url");
        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);

        Log.d("Response", ">" + "2000");
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();
        /**
         * Updating parsed JSON data into ListView
         * */

        ListAdapter adapter = new SimpleAdapter(MovieActivity.this, movieList, R.layout.list_item, 
                new String[] { TAG_RNUM, TAG_OPENDT, TAG_MOVIENM }, new int[] { R.id.rnum, R.id.opendt, R.id.movienm });


        setListAdapter(adapter);
    }

}

}

public class ServiceHandler {

static String response = null;
public final static int GET = 1;
public final static int POST = 2;

public ServiceHandler() {

}

/**
 * Making service call
 * @url - url to make request
 * @method - http request method
 * */
public String makeServiceCall(String url, int method) {
    return this.makeServiceCall(url, method, null);
}

/**
 * Making service call
 * @url - url to make request
 * @method - http request method
 * @params - http request params
 * */
public String makeServiceCall(String url, int method,
        List<NameValuePair> params) {
    try {
        // http client
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpEntity httpEntity = null;
        HttpResponse httpResponse = null;

        // Checking http request method type
        if (method == POST) {
            HttpPost httpPost = new HttpPost(url);
            // adding post params
            if (params != null) {
                httpPost.setEntity(new UrlEncodedFormEntity(params));
            }

            httpResponse = httpClient.execute(httpPost);

        } else if (method == GET) {
            // appending params to url
            if (params != null) {
                String paramString = URLEncodedUtils
                        .format(params, "utf-8");
                url += "?" + paramString;
            }
            HttpGet httpGet = new HttpGet(url);

            httpResponse = httpClient.execute(httpGet);

        }
        httpEntity = httpResponse.getEntity();
        response = EntityUtils.toString(httpEntity);

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return response;

}

}

私の Logcat トレース

01-09 22:13:08.625: E/AndroidRuntime(27625): 致命的な例外: メイン 01-09 22:13:08.625: E/AndroidRuntime(27625): java.lang.RuntimeException: アクティビティ ComponentInfo{com を開始できません。 example.test_06/com.example.test_06.MovieActivity}: java.lang.NullPointerException 01-09 22:13:08.625: E/AndroidRuntime(27625): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110) で 01 -09 22:13:08.625: E/AndroidRuntime(27625): android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135) 01-09 22:13:08.625: E/AndroidRuntime(27625): android.app で.ActivityThread.access$700(ActivityThread.java:140) 01-09 22:13:08.625: E/AndroidRuntime(27625): android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237) 01-09 22: 13:08.625: E/AndroidRuntime(27625): android.os.Handler.dispatchMessage(Handler.java:99) 01-09 22:13:08.625: E/AndroidRuntime(27625): android.os.Looper.loop(Looper.java:137) 01-09 22:13:08.625: E/AndroidRuntime(27625): at android.app.ActivityThread.main(ActivityThread.java:4946) 01-09 22:13:08.625: E/AndroidRuntime(27625): java.lang.reflect.Method.invokeNative(ネイティブ メソッド) 01-09 22:13 で:08.625: E/AndroidRuntime(27625): java.lang.reflect.Method.invoke(Method.java:511) 01-09 22:13:08.625: E/AndroidRuntime(27625): com.android.internal. os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1036) 01-09 22:13:08.625: E/AndroidRuntime(27625): com.android.internal.os.ZygoteInit.main(ZygoteInit.java:803) 01 -09 22:13:08.625: E/AndroidRuntime(27625): dalvik.system.NativeStart.main(Native Method) 01-09 22:13:08.625: E/AndroidRuntime(27625): 原因: java.lang. NullPointerException 01-09 22:13:08.625:E/AndroidRuntime(27625): com.example.test_06.MovieActivity.onCreate(MovieActivity.java:76) 01-09 22:13:08.625: E/AndroidRuntime(27625): android.app.Activity.performCreate(Activity) .java:5206) 01-09 22:13:08.625: E/AndroidRuntime(27625): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 01-09 22:13:08.625: E/AndroidRuntime(27625) ): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) 01-09 22:13:08.625: E/AndroidRuntime(27625): ... 11 もっと見る625: E/AndroidRuntime(27625): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) 01-09 22:13:08.625: E/AndroidRuntime(27625): ... 11 もっと見る625: E/AndroidRuntime(27625): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) 01-09 22:13:08.625: E/AndroidRuntime(27625): ... 11 もっと見る

別のエラーを添付しました... 3 時間について深く考えます TT

Answer 1

nullポインタ例外が発生しています-

21:15:52.795: E/AndroidRuntime(20193): 原因: java.lang.NullPointerException 01-09

onCreate() メソッド内で btn1 を初期化していないためです。この行を onCreate()- 内に記述します。

btn1 = (Button) findViewById(R.id.button1);

Answer 2

findViewById() は setContentView() の後に呼び出す必要があります。ドキュメント：

onCreate(Bundle) で処理された XML から id 属性で識別されるビューを検索します。

つまり、ボタンの宣言を次のように変更します。

private Button btn1;

次に、onCreate() で、setContentView() の後にボタンを見つけます。

setContentView(R.layout.activity_main);
btn1 = (Button) findViewById(R.id.button1);

Answer 3

AndroidでメソッドをViews呼び出した後はいつでもアクセスできます。setContentView()レイアウトをインフレートしないと、宣言部分からビューに直接アクセスできません。

宣言部分ではなく、あなたのButton内部を宣言してくださいonCreate()。

public class MainActivity extends Activity {

private static final int GET_MOVIE = 1000;
private Button btn1;
private String movie;
Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

   btn1 = (Button) findViewById(R.id.button1);
   movie = btn1.getText().toString();

また、以下のコードonCreate()のみを含める必要があります。そして、あなたの価値を得るには、代わりにTextView書くべきですString movie = t.getText().toString();String movie=t.toString();

TextView t = (TextView) findViewById(R.id.movienm);
movie = t.getText().toString();
.
.
.

ListView lv = (ListView) findViewById(android.R.id.list);
    Log.e("kjw", "outlistener");

    Intent i = getIntent();

    movie = i.getStringExtra("movie");
    lv.setOnItemClickListener(new OnItemClickListener() {


        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {

            Intent i = getIntent();
            movie = i.getStringExtra("movie");
            i.putExtra("return", movie);
            setResult(RESULT_OK, i);
            finish();               
        }

    });
  }

Answer 4

これbtn1 = (Button) findViewById(R.id.button1);

 private Button btn1;   
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 btn1 = (Button) findViewById(R.id.button1);

後に onCreate にする必要がありますsetContentView

findViewById現在のインフレートされたレイアウトで id を持つビューを探します。したがって、最初にレイアウトのコンテンツをアクティビティに設定してから、ビューを初期化する必要があります。

また

private String movie;
private Button btn1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn1 = (Button) findViewById(R.id.button1);
    movie = btn1.getText().toString();