如何使 phone 的后退按钮像操作栏中的向上按钮一样工作？

Question

出于某种原因，按后退按钮会造成一些麻烦。但是action bar上的后退箭头，也就是向上导航，没有任何问题。我看到了使向上按钮像后退按钮一样工作的答案，但我还没有看到任何使 后退按钮像向上按钮 一样工作的答案。

提前致谢！

public class ListEventActivity extends ActionBarActivity {
JSONObject json = new JSONObject();
JSONArray jarr = new JSONArray();
JSONObject jobj = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list_event);
    Intent intent = getIntent();
    Bundle extras = intent.getExtras();
    int year = extras.getInt("year");
    int month = extras.getInt("month");
    int day = extras.getInt("day");

    try {
        json.put("year", year);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    try {
        json.put("month", month);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    try {
        json.put("day", day);
    } catch (JSONException e) {
        e.printStackTrace();
    }


    PostData pd = new PostData();
    pd.execute();

    try {
        pd.get(1000, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    } catch (TimeoutException e) {
        e.printStackTrace();
    }

    RecyclerView recList = (RecyclerView) findViewById(R.id.cardList);
    recList.setHasFixedSize(true);
    LinearLayoutManager llm = new LinearLayoutManager(this);
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    recList.setLayoutManager(llm);

    EventAdapter ea = new EventAdapter(createList(jarr.length()));
    recList.setAdapter(ea);
}

private List<EventInfo> createList(int size) {
    List<EventInfo> result = new ArrayList<EventInfo>();
    for (int i = 0; i < size; i++) {
        EventInfo ei = new EventInfo();
        try {
            jobj = jarr.getJSONObject(i);
            ei.id = Integer.parseInt(jobj.getString("id"));
            ei.title = jobj.getString("title");
            ei.startDatetime = jobj.getString("startDate");
            ei.pictureURL = jobj.getString("pictureURL");
            ei.type = jobj.getString("type");
            ei.contact = jobj.getString("contact");
            ei.endDatetime = jobj.getString("endDate");
            ei.location = jobj.getString("location");
            ei.description = jobj.getString("description");
        } catch (JSONException e) {
            e.printStackTrace();
        }
        result.add(ei);
    }
    return result;
}

@Override
public void onBackPressed() {
    super.onBackPressed();
    finish();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_list_event, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

class PostData extends AsyncTask<String, Void, Void> {

    @Override
    protected Void doInBackground(String... params) {
        ClientServerInterface clientServerInterface = new ClientServerInterface();
        jarr = clientServerInterface.postData("http://54.164.136.46/decodejson.php", json);
        return null;
    }
}
}

基本上，这个 activity 是在用户单击日历上的日期时启动的。应用程序将 JSON 年月日数据发送到服务器，服务器在数据库上运行查询，并且 return 是一个 JSON 事件详细信息数组。只有当 JSON 数组中有多个元素时才会出现此问题。发生的情况是，当您单击后退时，它会将您带到一个只有事件的 ListEventActivity，然后您必须再次单击后退以 return 到日历。使用操作栏上的向上箭头时不会发生这种情况。

Answer 1

这是您要找的吗？

@Override
public void onBackPressed() {
        super.onBackPressed();
        pd.cancel(true);
        finish();
}

Answer 2

override fun onBackPressed() {
      super.onBackPressed()
      NavUtils.navigateUpFromSameTask(this)
}

此代码使用 Kotlin，您可以轻松将其转换为 Java。

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