Java 如何在片段中而不是在活动中使用setContentView
亲爱的飞越者:)Java 如何在片段中而不是在活动中使用setContentView,java,android,android-fragments,setcontentview,Java,Android,Android Fragments,Setcontentview,亲爱的飞越者:) AllAssetsFragment从Main活动打开。在这个片段中,我无法正确设置setContentView()和getApplicationContext() 我知道有点不对劲。一些代码适用于正常的活动,但在此片段中它们不起作用 AllAssetsFragment: import android.content.Intent; import android.os.Bundle; import androidx.appcompat.app.AppCompatActivit
AllAssetsFragment
从Main活动打开。在这个片段中,我无法正确设置setContentView()
和getApplicationContext()
我知道有点不对劲。一些代码适用于正常的活动,但在此片段中它们不起作用
AllAssetsFragment:
import android.content.Intent;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.room.Room;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class AllAssetsFragment extends Fragment {
public AllAssetsFragment(){
}
private static final String HI = "https://uniqueandrocode.000webhostapp.com/hiren/favouritelist.php";
private List<AssetsItem>assetsItems;
private RecyclerView recyclerView;
AssetsAdapter adapter;
private JsonArrayRequest request;
private RequestQueue requestQueue;
public static FavoritesDatabase favoritesDatabase;
Button btn;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_allassets, container, false);
recyclerView = (RecyclerView)getView().findViewById(R.id.recyclerview);
recyclerView.setHasFixedSize(true);
// +++ PROBLEM 1: Context doesn't work (same on Problem 3 and 4) +++
recyclerView.setLayoutManager(new LinearLayoutManager(this));
assetsItems = new ArrayList<>();
btn=(Button)getView().findViewById(R.id.favbtn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// +++ PROBLEM 2: This code doesn't work to open Fragment from Fragment +++
startActivity(new Intent(AllAssetsFragment.this, FavoritesFragment.class));
}
});
favoritesDatabase = Room.databaseBuilder(getActivity().getApplicationContext(), FavoritesDatabase.class, "myfavdb").allowMainThreadQueries().build();
getData();
}
private void getData() {
request = new JsonArrayRequest(HI, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
JSONObject jsonObject = null;
for (int i = 0; i < response.length(); i++) {
try {
JSONObject ob = response.getJSONObject(i);
AssetsItem pr = new AssetsItem(ob.getInt("id"),
ob.getString("product_name"),
ob.getString("product_img"));
assetsItems.add(pr);
} catch (JSONException e) {
e.printStackTrace();
}
}
setupData(assetsItems);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
// +++ PROBLEM 3: Context doesn't work +++
requestQueue = Volley.newRequestQueue(this);
requestQueue.add(request);
}
private void setupData(List<AssetsItem>assetsItems){
adapter=new AssetsAdapter(assetsItems,getActivity().getApplicationContext());
recyclerView.setAdapter(adapter);
}
}
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;
/**
* A simple {@link Fragment} subclass.
*/
public class FavoritesFragment extends Fragment {
public FavoritesFragment() {
}
private RecyclerView rv;
private FavoritesAdapter adapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_favorites, container, false);
rv=(RecyclerView)getView().findViewById(R.id.rec);
rv.setHasFixedSize(true);
// +++ PROBLEM 4: doesn't work +++
rv.setLayoutManager(new LinearLayoutManager(this));
getFavData();
}
private void getFavData(){
List<FavoritesItem>favoritesItems=AllAssetsFragment.favoritesDatabase.favoritesDao().getFavoritesData();
adapter = new FavoritesAdapter(favoritesItems,getActivity().getApplicationContext());
rv.setAdapter(adapter);
}
}
导入android.content.Intent;
导入android.os.Bundle;
导入androidx.appcompat.app.appcompat活动;
导入androidx.fragment.app.fragment;
导入androidx.recyclerview.widget.LinearLayoutManager;
导入androidx.recyclerview.widget.recyclerview;
导入androidx.room.room;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.view.ViewGroup;
导入android.widget.Button;
导入com.android.volley.RequestQueue;
导入com.android.volley.Response;
导入com.android.volley.VolleyError;
导入com.android.volley.toolbox.JsonArrayRequest;
导入com.android.volley.toolbox.volley;
导入org.json.JSONArray;
导入org.json.JSONException;
导入org.json.JSONObject;
导入java.util.ArrayList;
导入java.util.List;
公共类AllAssetsFragment扩展了片段{
公共AllAssetsFragment(){
}
私有静态最终字符串HI=”https://uniqueandrocode.000webhostapp.com/hiren/favouritelist.php";
私人上市资产项目;
私人回收站;
资产适配器;
私有JsonArrayRequest请求;
私有请求队列请求队列;
公共静态收藏夹数据库收藏夹数据库;
按钮btn;
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
返回充气机。充气(R.layout.fragment_allassets,容器,假);
RecycleView=(RecycleView)getView().findViewById(R.id.RecycleView);
recyclerView.setHasFixedSize(true);
//+++问题1:上下文不起作用(与问题3和4相同)+++
recyclerView.setLayoutManager(新的LinearLayoutManager(本));
assetsItems=新的ArrayList();
btn=(按钮)getView().findViewById(R.id.favbtn);
btn.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
//+++问题2:此代码无法从片段中打开片段+++
startActivity(新意图(AllAssetsFragment.this,FavoritesFragment.class));
}
});
favoritesDatabase=Room.databaseBuilder(getActivity().getApplicationContext(),favoritesDatabase.class,“myfavdb”).allowMainThreadQueries().build();
getData();
}
私有void getData(){
request=newjsonarrayrequest(嗨,newresponse.Listener(){
@凌驾
公共void onResponse(JSONArray响应){
JSONObject JSONObject=null;
对于(int i=0;i
这里是我们的第二个片段:FavoritesFragment:
import android.content.Intent;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.room.Room;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class AllAssetsFragment extends Fragment {
public AllAssetsFragment(){
}
private static final String HI = "https://uniqueandrocode.000webhostapp.com/hiren/favouritelist.php";
private List<AssetsItem>assetsItems;
private RecyclerView recyclerView;
AssetsAdapter adapter;
private JsonArrayRequest request;
private RequestQueue requestQueue;
public static FavoritesDatabase favoritesDatabase;
Button btn;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_allassets, container, false);
recyclerView = (RecyclerView)getView().findViewById(R.id.recyclerview);
recyclerView.setHasFixedSize(true);
// +++ PROBLEM 1: Context doesn't work (same on Problem 3 and 4) +++
recyclerView.setLayoutManager(new LinearLayoutManager(this));
assetsItems = new ArrayList<>();
btn=(Button)getView().findViewById(R.id.favbtn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// +++ PROBLEM 2: This code doesn't work to open Fragment from Fragment +++
startActivity(new Intent(AllAssetsFragment.this, FavoritesFragment.class));
}
});
favoritesDatabase = Room.databaseBuilder(getActivity().getApplicationContext(), FavoritesDatabase.class, "myfavdb").allowMainThreadQueries().build();
getData();
}
private void getData() {
request = new JsonArrayRequest(HI, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
JSONObject jsonObject = null;
for (int i = 0; i < response.length(); i++) {
try {
JSONObject ob = response.getJSONObject(i);
AssetsItem pr = new AssetsItem(ob.getInt("id"),
ob.getString("product_name"),
ob.getString("product_img"));
assetsItems.add(pr);
} catch (JSONException e) {
e.printStackTrace();
}
}
setupData(assetsItems);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
// +++ PROBLEM 3: Context doesn't work +++
requestQueue = Volley.newRequestQueue(this);
requestQueue.add(request);
}
private void setupData(List<AssetsItem>assetsItems){
adapter=new AssetsAdapter(assetsItems,getActivity().getApplicationContext());
recyclerView.setAdapter(adapter);
}
}
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;
/**
* A simple {@link Fragment} subclass.
*/
public class FavoritesFragment extends Fragment {
public FavoritesFragment() {
}
private RecyclerView rv;
private FavoritesAdapter adapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_favorites, container, false);
rv=(RecyclerView)getView().findViewById(R.id.rec);
rv.setHasFixedSize(true);
// +++ PROBLEM 4: doesn't work +++
rv.setLayoutManager(new LinearLayoutManager(this));
getFavData();
}
private void getFavData(){
List<FavoritesItem>favoritesItems=AllAssetsFragment.favoritesDatabase.favoritesDao().getFavoritesData();
adapter = new FavoritesAdapter(favoritesItems,getActivity().getApplicationContext());
rv.setAdapter(adapter);
}
}
导入android.os.Bundle;
导入androidx.appcompat.app.appcompat活动;
导入androidx.fragment.app.fragment;
导入androidx.recyclerview.widget.LinearLayoutManager;
导入androidx.recyclerview.widget.recyclerview;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.view.ViewGroup;
导入java.util.List;
/**
*一个简单的{@link Fragment}子类。
*/
公共类FavoritesFragment扩展了片段{
公共偏好片段(){
}
私人回收车;
专用收藏夹适配器;
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
返回充气机。充气(R.layout.fragment\u收藏夹,容器,假);
rv=(RecyclerView)getView().findviewbyd(R.id.rec);
rv.setHasFixedSize(真);
//+++问题4:不起作用+++
rv.setLayoutManager(新直线布局经理(本));
getFavData();
}
私有void getFavData(){
ListfavoritesItems=AllAssetsFragment.favoritesDatabase.favoritesDao().getFavoritesData();
适配器=新的FavoritesAdapter(favoritesItems,getActivity().getApplicationContext());
rv.设置适配器(适配器);
}
}
您不需要在片段中调用setContentView
,您需要在onCreateView
方法中返回视图。你已经做了
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_allassets, container, false);
}
对于getApplicationContext
您需要调用getActivity()
像这样
getActivity().getApplicationContext()
您不需要在onCreateView
方法中调用setContentView
片段中的返回视图。你已经做了
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_allassets, container, false);
}
对于getApplicationContext
您需要调用getActivity()
像这样
getActivity().getApplicationContext()
不要使用
FragmentTransaction transaction = getActivity().getFragmentManager().beginTransaction();
transaction.replace(R.id.container, new AllAssetsFragment());
transaction.commit();