Question

我在Activity中有一个TabLayout和ViewPager。我正在使用单个片段来创建标签页。我正在从那个片段打开一个Activity。当我点击手机的后退按钮返回TabLayout活动（带片段）时，它工作正常。但是当我使用工具栏的后退按钮时，TabLayout活动没有打开，而是显示空白页面。当我现在按下手机的后退按钮时，只显示TabLayout活动。我有什么办法可以解决这个问题吗？

public class ProdDetailsActivity extends AppCompatActivity{


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_proddetails);

        Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem menuItem) {
        switch (menuItem.getItemId()){
            case android.R.id.home:
          // This is not working
                onBackPressed();
                finish();
        }
        return super.onOptionsItemSelected(menuItem);
    }


}

// Fragment inside TabLayout Activity

public class SubCatFrag extends Fragment{

    private TextView emptytxt;
    private ListView listView;
    private ArrayList<Model> mListData=new ArrayList<>();
    private CustomListAdapter adapter;
    private ConnectionDetector cd;
    public String userid;
    SharedPreferences sharedpreferences;
    private ProgressDialog pd;
    private static final int RQST_ONE = 1;
    private static final int RQST_TWO = 2;

    public static SubCatFrag newInstance(int index) {
        SubCatFrag myFragment = new SubCatFrag();

        Bundle args = new Bundle();
        args.putInt("index", index);
        myFragment.setArguments(args);

        return(myFragment);
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.subcatfrag, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);


        ((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("LIST PRODUCT");

        emptytxt = (TextView)view.findViewById(R.id.emptytxt);

        listView = (ListView)view.findViewById(R.id.list);

        pd = new ProgressDialog(getActivity());
        cd = new ConnectionDetector(getActivity());

        if(cd.isConnectingToInternet()){
            fetchDetails();
        }else{
            Toast.makeText(getActivity(), "No Internet Available", Toast.LENGTH_SHORT).show();
        }

        adapter = new CustomListAdapter(getActivity(), R.layout.productlistrowlayout, mListData);
        listView.setAdapter(adapter);
        listView.setEmptyView(emptytxt);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                String prod=mListData.get(position).getProd_id();
                String title=mListData.get(position).getTitle();
                Intent intent = new Intent(getActivity(), ProdDetailsActivity.class);
                intent.putExtra("prd_id",prod);
                intent.putExtra("title",title);
                startActivityForResult(intent,RQST_TWO);
            }
        });


    }

    private void fetchDetails() {

        pd.setMessage("Please wait..");
        pd.show();

        sharedpreferences = getActivity().getSharedPreferences("MyPREFERENCES", Context.MODE_PRIVATE);
        userid=sharedpreferences.getString("userid","");
        System.out.println("usersam_"+" "+userid);

        if(mListData!=null )mListData.clear();

        StringRequest stringRequest = new StringRequest(Request.Method.POST, URLUtil.FETCHLIST,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                        pd.dismiss();

                        try {

                            JSONObject obj1 = new JSONObject(response);
                            JSONArray jsonArray = obj1.getJSONArray("allProducts");
                            for(int i=0; i<jsonArray.length(); i++){
                                JSONObject obj = jsonArray.getJSONObject(i);

                                if(obj.length() != 0 ){
                                    Model model = new Model();
                                    model.setImage(obj.getString("prd_img"));
                                    model.setTitle(obj.getString("title"));
                                    model.setDate(obj.getString("date"));
                                    model.setPrice(obj.getString("price"));
                                    model.setProd_id(obj.getString("id"));
                                    double rate = i + (i*0.1);
                                    model.setRate(String.valueOf(rate));

                                    mListData.add(model);
                                }


                            }

                            adapter.notifyDataSetChanged();


                        } catch (JSONException e) {
                            e.printStackTrace();
                            //Toast.makeText(HomeActivity.this, "Json error: " + e.getMessage(), Toast.LENGTH_LONG).show();
                        }
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                //Toast.makeText(getActivity(), "VolleyError" + error.toString(), Toast.LENGTH_LONG).show();
                pd.dismiss();
                if (error instanceof TimeoutError || error instanceof NoConnectionError) {
                    Toast.makeText(getActivity(),getActivity().getString(R.string.error_network_timeout),Toast.LENGTH_LONG).show();
                } else if (error instanceof AuthFailureError) {
                    //TODO
                } else if (error instanceof ServerError) {
                    //TODO
                } else if (error instanceof NetworkError) {
                    //TODO
                } else if (error instanceof ParseError) {
                    //TODO
                }
            }
        }) {
            @Override
            protected Map<String, String> getParams() {
                Map<String, String> params = new HashMap<String, String>();

                params.put("user_id", userid);
                return params;
            }

        };

        RequestQueue requestQueue = Volley.newRequestQueue(getActivity());
        requestQueue.add(stringRequest);
        stringRequest.setRetryPolicy(new DefaultRetryPolicy(
                10000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(resultCode==RESULT_OK && requestCode==RQST_ONE){
            fetchDetails();
        }else if(resultCode==RESULT_OK && requestCode==RQST_TWO){
            fetchDetails();
        }
    }
}

Answer 1

尝试使用此代码而不是onOptionsItemSelected .....工具栏工具栏=（工具栏）findViewById（R.id.toolbar）; setSupportActionBar（栏）;

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowHomeEnabled(true);

    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent goBack = new Intent(getApplicationContext(),YourActivity.class);
            startActivity(goBack);
            finish();
        }
    });

Answer 2

在onCreate（）中编写以下代码：

 Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setHomeButtonEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onBackPressed();
            }
        });

并在您的课程中添加以下代码：

  @Override
public void onBackPressed() {
        Intent prev = new Intent(getApplicationContext(),PreviousActivity.class);
        startActivity(prev);
    finish();
}

从Activity回到片段

2 个答案: