如何实现onBack pressed（）及在片段意图？ [英] How to implement onBackPressed() & intents in fragment?

问题描述

我知道onBack pressed（）是活性的方法，但是，我想用在片段的功能，例如，当后退按钮是pressed，它就会通过意向重定向到另一个活动。有没有什么解决办法？

 公共类News_Events_fragment扩展片段{
ProgressDialog PD;
ListView控件LV1;
共享preferences共享preferences = NULL;
INT NotiCount;
TextView的txt_title，txt_msg，TextView的;
上下文语境;
意向意图;
ArrayList的＆LT; SliderMsgTitleModel＆GT; CurrentOfficersPastList;
NewsActivityAdapter pastAdapter;

@覆盖
公共查看onCreateView（LayoutInflater充气，容器的ViewGroup，
        捆绑savedInstanceState）{

    上下文=（上下文）getActivity（）;

    查看rootView = inflater.inflate（R.layout.activity_news，集装箱，假）;

    新的AsyncTask＆LT;虚空，虚空，ArrayList的＆LT; SliderMsgTitleModel＆GT;＆GT;（）{

        在preExecute保护无效（）{
            PD =新ProgressDialog（getActivity（））;
            pd.setCancelable（真正的）;
            pd.setTitle（UPOA）;
            pd.setMessage（请稍候，装载数据......）;
            pd.show（）;
        }

        @覆盖
        受保护的ArrayList＆LT; SliderMsgTitleModel＆GT; doInBackground（
                虚空...... PARAMS）{
            的System.out.println（背景）;
            CurrentOfficersPastList =新的ArrayList＆LT; SliderMsgTitleModel＆GT;（）;
            对选定的导航抽屉的项目//显示视图
            ParseQuery＆LT;的parseObject＆GT;查询= ParseQuery.getQuery（信息）;
            query.whereEqualTo（featured_status，真正的）;
            // query.whereEqualTo（push_status，真正的）;

            query.orderByDescending（updatedAt）;

            query.selectKeys（Arrays.asList（标题））;
            query.selectKeys（Arrays.asList（信息））;
            尝试 {
                query.setCachePolicy（ParseQuery.CachePolicy.NETWORK_ELSE_CACHE）;
                名单＆LT;的parseObject＆GT;结果= query.find（）;
                的for（int i = 0; I＆LT; results.size（）;我++）{
                    的parseObject对象= results.get（ⅰ）;
                    CurrentOfficersPastList.add（新SliderMsgTitleModel（
                            object.getString（标题），对象
                                    .getString（消息）））;
                    的System.out.println（标题==
                            + object.getString（标题）+＆放大器;＆安培;消息
                            + object.getString（信息）+大小
                            + CurrentOfficersPastList.size（））;

                }
            }赶上（例外五）{
                e.getMessage（）;
            }
            pd.dismiss（）;

            返回CurrentOfficersPastList;
        }

        @燮pressWarnings（未登记）
        @覆盖
        保护无效onPostExecute（ArrayList中＆LT; SliderMsgTitleModel＆GT;值）{

            pd.dismiss（）;
            / *意图ENT =新的意向书（getActivity（），NewsActivity.class）;
            ent.putExtra（新闻列表（ArrayList中＆LT; SliderMsgTitleModel＆GT;）值）;
            startActivity（ENT）;
            的System.out.println（价值是+ value.size（））; * /

            CurrentOfficersPastList =新的ArrayList＆LT; SliderMsgTitleModel＆GT;（）;
            CurrentOfficersPastList =价值;
            LV1 =（ListView控件）getActivity（）findViewById（R.id.list_title）。
            pastAdapter =新NewsActivityAdapter（getActivity（），R.layout.activity_news_txt，CurrentOfficersPastList）;
            lv1.setAdapter（pastAdapter）;

        }
    }。执行（）;

    返回rootView;
}

公共无效onBack pressed（）{
    // TODO自动生成方法存根
    //super.onBack$p$pssed（）;
    //Toast.makeText（getApplicationContext（），咔嚓，2000年）.show（）;
            字符串cameback =CameBack;
            意图=新的意图（getActivity（），HomeActivity.class）;
            intent.putExtra（Comingback，cameback）;
            startActivity（意向）;
}

 }
 

解决方案

覆盖onBack pressed中的onkeydown代替。不必要 。但是，这对我的作品

 公共布尔的onkeydown（INT键code，KeyEvent的事件）{

        开关（钥匙code）{
            案例KeyEvent.KEY code_BACK：
                字符串cameback =CameBack;
                意图=新的意图（getActivity（），HomeActivity.class）;
                intent.putExtra（Comingback，cameback）;
                startActivity（意向）;
                返回true
    }
            返回false;
}
 

I know that onBackPressed() is a method in activity but, I want to use the functionality in fragments such that when back button is pressed, it gets redirected to another activity via Intent. Is there any solution to this ?

public class News_Events_fragment extends Fragment {
ProgressDialog pd;
ListView lv1;
SharedPreferences sharedPreferences = null;
int NotiCount;
TextView txt_title, txt_msg, textView;
Context context;
Intent intent ;
ArrayList<SliderMsgTitleModel> CurrentOfficersPastList;
NewsActivityAdapter pastAdapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    context = (Context) getActivity();

    View rootView = inflater.inflate(R.layout.activity_news, container, false);

    new AsyncTask<Void, Void, ArrayList<SliderMsgTitleModel>>() {

        protected void onPreExecute() {
            pd = new ProgressDialog(getActivity());
            pd.setCancelable(true);
            pd.setTitle("UPOA");
            pd.setMessage("Please wait,loading the data...");
            pd.show();
        }

        @Override
        protected ArrayList<SliderMsgTitleModel> doInBackground(
                Void... params) {
            System.out.println("In Background");
            CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
            // display view for selected nav drawer item
            ParseQuery<ParseObject> query = ParseQuery.getQuery("message");
            query.whereEqualTo("featured_status", true);
            // query.whereEqualTo("push_status", true);

            query.orderByDescending("updatedAt");

            query.selectKeys(Arrays.asList("title"));
            query.selectKeys(Arrays.asList("message"));
            try {
                query.setCachePolicy(ParseQuery.CachePolicy.NETWORK_ELSE_CACHE);
                List<ParseObject> results = query.find();
                for (int i = 0; i < results.size(); i++) {
                    ParseObject object = results.get(i);
                    CurrentOfficersPastList.add(new SliderMsgTitleModel(
                            object.getString("title"), object
                                    .getString("message")));
                    System.out.println("title is=="
                            + object.getString("title") + "&& message is"
                            + object.getString("message") + "size is"
                            + CurrentOfficersPastList.size());

                }
            } catch (Exception e) {
                e.getMessage();
            }
            pd.dismiss();

            return CurrentOfficersPastList;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void onPostExecute(ArrayList<SliderMsgTitleModel> value) {

            pd.dismiss();
            /*Intent ent = new Intent(getActivity(), NewsActivity.class);
            ent.putExtra("NEWSLIST", (ArrayList<SliderMsgTitleModel>) value);
            startActivity(ent);
            System.out.println("Value is" + value.size());*/

            CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
            CurrentOfficersPastList = value;
            lv1 = (ListView) getActivity().findViewById(R.id.list_title);
            pastAdapter = new NewsActivityAdapter(getActivity(), R.layout.activity_news_txt, CurrentOfficersPastList);
            lv1.setAdapter(pastAdapter);

        }
    }.execute();

    return rootView;
}

public void onBackPressed() {
    // TODO Auto-generated method stub
    //super.onBackPressed();
    //Toast.makeText(getApplicationContext(), "click",2000).show();
            String cameback="CameBack";
            intent = new Intent(getActivity(),HomeActivity.class);
            intent.putExtra("Comingback", cameback);
            startActivity(intent);
}

 }

解决方案

Override onKeyDown instead of onBackPressed. Not necessarily . But this works for me

public boolean onKeyDown(int keyCode, KeyEvent event) {

        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                String cameback="CameBack";
                intent = new Intent(getActivity(),HomeActivity.class);
                intent.putExtra("Comingback", cameback);
                startActivity(intent);
                return true
    }
            return false;
}

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