Android 将数据从活动传递到第一次未加载的片段
我试图将数据从一个活动传递到一个片段。我有四张账单。数据已传递，但第一次未显示，当我滑动其他三个选项卡并返回到第一个选项卡时，数据将显示。我在活动的onCreate方法中调用JSON数据解析方法。这里我提供我的代码。 这是Main@Activity.javaAndroid 将数据从活动传递到第一次未加载的片段,android,fragment,Android,Fragment,我试图将数据从一个活动传递到一个片段。我有四张账单。数据已传递，但第一次未显示，当我滑动其他三个选项卡并返回到第一个选项卡时，数据将显示。我在活动的onCreate方法中调用JSON数据解析方法。这里我提供我的代码。 这是Main@Activity.java package com.example.iqbal.privateuniversityinfo; import android.os.Bundle; import android.support.design.widget.Tab
package com.example.iqbal.privateuniversityinfo;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.android.volley.Request;
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;
// https://api.myjson.com/bins/lb6b8
// new https://api.myjson.com/bins/1gzo6k
public class Main2Activity extends AppCompatActivity {
String name, fac_and_sub, tution_fees, admission_info, contact;
private String div;
private int pos;
private RequestQueue mqueue;
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
private Bundle bundle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
div = getIntent().getStringExtra("div");
pos = Integer.parseInt(getIntent().getStringExtra("pos"));
bundle = new Bundle();
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
jsonParse();
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
}
@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_main2, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public static class PlaceholderFragment extends Fragment {
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.university_details, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
FacultyAndSubject facultyAndSubject = new FacultyAndSubject();
facultyAndSubject.setArguments(bundle);
return facultyAndSubject;
case 1:
TutionFees tutionFees = new TutionFees();
return tutionFees;
case 2:
Admission_info admission_info = new Admission_info();
return admission_info;
case 3:
Contact contact = new Contact();
return contact;
default:
return null;
}
}
@Override
public int getCount() {
// Show 4 total pages.
return 4;
}
}
private void jsonParse() {
String url = "https://api.myjson.com/bins/1gzo6k";
mqueue = Volley.newRequestQueue(this);
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, url, null, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
for (int i = 0; i < response.length(); i++) {
try {
JSONObject jsonObject = response.getJSONObject(i);
switch (div) {
case "ctg":
if (i == pos) {
name = jsonObject.getString("name");
fac_and_sub = jsonObject.getString("faculty_and_sub");
tution_fees = jsonObject.getString("tution_fees");
admission_info = jsonObject.getString("admission_info");
contact = jsonObject.getString("contact");
bundle.putString("name", name);
bundle.putString("fac", fac_and_sub);
bundle.putString("fees", tution_fees);
bundle.putString("info", admission_info);
bundle.putString("contact", contact);
}
break;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
mqueue.add(jsonArrayRequest);
}
}
尝试将代码添加到
开关的案例0
中，与默认案例相同
同样按照@babich的建议，请在收到响应后尝试设置适配器。是否需要在收到数据后设置viewPager？
将完成日志消息添加到您的onResponse
end，并将其添加到FacultyAndSubject的onCreateView
而不是提前检查电话。
您知道如何添加日志消息以及如何使用LogCat
public class SectionsPagerAdapter extends FragmentPagerAdapter {
FacultyAndSubject facultyAndSubject;
TutionFees tutionFees;
Admission_info admission_info;
Contact contact;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
if(facultyAndSubject == null) {
facultyAndSubject = new FacultyAndSubject();
facultyAndSubject.setArguments(bundle);
}
return facultyAndSubject;
case 1:
if(tutionFees == null) tutionFees = new TutionFees();
return tutionFees;
case 2:
if(admission_info == null) admission_info = new Admission_info();
return admission_info;
case 3:
if(contact == null) contact = new Contact();
return contact;
default:
return null;
}
}
@Override
public int getCount() {
// Show 4 total pages.
return 4;
}
}
第一：
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.faculty_and_subject, container, false);
tv = v.findViewById(R.id.tv);
if (getArguments() != null) {
this.name = getArguments().getString("name");
this.fac = getArguments().getString("fac");
this.fees = getArguments().getString("fees");
this.info = getArguments().getString("info");
this.contact = getArguments().getString("contact");
updateData();
} else showLoading();
tv.setText(name + "\n" + " " + fac + "\n" + fees + "\n" + info + "\n" + contact);
return v;
}
public void updateData(String name, String fac, String fees, String info, String contact) {
stopLoading();
this.name = name;
this.fac = fac;
this.fees = fees;
this.info = info;
this.contact = contact;
}
第二点：
@Override
public void onResponse(JSONArray response) {
for (int i = 0; i < response.length(); i++) {
try {
JSONObject jsonObject = response.getJSONObject(i);
switch (div) {
case "ctg":
if (i == pos) {
name = jsonObject.getString("name");
fac_and_sub = jsonObject.getString("faculty_and_sub");
tution_fees = jsonObject.getString("tution_fees");
admission_info = jsonObject.getString("admission_info");
contact = jsonObject.getString("contact");
if(mSectionsPagerAdapter.facultyAndSubject != null) {
mSectionsPagerAdapter.facultyAndSubject.
updateDate(name, fac, fees, info, contact)
} else {
mSectionsPagerAdapter.facultyAndSubject = new FacultyAndSubject();
Bundle bundle = new Bundle();
bundle.putString("name", name);
bundle.putString("fac", fac_and_sub);
bundle.putString("fees", tution_fees);
bundle.putString("info", admission_info);
bundle.putString("contact", contact);
facultyAndSubject.setArguments(bundle);
}
}
break;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
@覆盖
公共void onResponse（JSONArray响应）{
对于（int i=0；i
09-04 00:27:51.175 6747-6747/com.example.iqbal.private university信息E/AAA:FacultyAndSubject call 09-04 00:28:02.386 6747-6747/com.example.iqbal.private university信息E/AAA:onResponse finishedFirst调用FacultyAndSubject这就是它第一次变为空的原因你能告诉我如何设置viewPager吗？@zhiki认为你必须检查一下吗在FacultyAndSubject中，没有数据，如果仍然没有数据，则显示加载微调器。在这种情况下，这是最好的解决方案。还有一件事。如果全局声明片段，并在fragment==null
时创建它们，效果会更好。在jsonParse
中再次检查FacultyAndSubject
是否为空。如果为空，则使用数据创建它；如果不为空，则更新数据。
@Override
public void onResponse(JSONArray response) {
for (int i = 0; i < response.length(); i++) {
try {
JSONObject jsonObject = response.getJSONObject(i);
switch (div) {
case "ctg":
if (i == pos) {
name = jsonObject.getString("name");
fac_and_sub = jsonObject.getString("faculty_and_sub");
tution_fees = jsonObject.getString("tution_fees");
admission_info = jsonObject.getString("admission_info");
contact = jsonObject.getString("contact");
if(mSectionsPagerAdapter.facultyAndSubject != null) {
mSectionsPagerAdapter.facultyAndSubject.
updateDate(name, fac, fees, info, contact)
} else {
mSectionsPagerAdapter.facultyAndSubject = new FacultyAndSubject();
Bundle bundle = new Bundle();
bundle.putString("name", name);
bundle.putString("fac", fac_and_sub);
bundle.putString("fees", tution_fees);
bundle.putString("info", admission_info);
bundle.putString("contact", contact);
facultyAndSubject.setArguments(bundle);
}
}
break;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}