Java 为什么我的自定义listview没有显示任何内容?
我正在制作一个列表视图,以显示codeforces中所有即将举行的比赛。因此,我创建了一个Java 为什么我的自定义listview没有显示任何内容?,java,android,listview,android-fragments,Java,Android,Listview,Android Fragments,我正在制作一个列表视图,以显示codeforces中所有即将举行的比赛。因此,我创建了一个CodeforcesContest对象和一个包含ListView的片段。我希望有关竞赛的所有信息都在ListView的一行中。竞赛信息是竞赛名称、竞赛时间和保存站点名称的另一个字符串,该字符串始终为“Codeforces”。这是我到目前为止所拥有的。我对Java和android非常陌生。我已经搜索并找到了使用自定义类实现自定义listview的方法。但是,我的listview没有显示任何内容。我正在使用an
CodeforcesContest
对象和一个包含ListView
的片段。我希望有关竞赛的所有信息都在ListView的一行中。竞赛信息是竞赛名称、竞赛时间和保存站点名称的另一个字符串,该字符串始终为“Codeforces”。这是我到目前为止所拥有的。我对Java和android非常陌生。我已经搜索并找到了使用自定义类实现自定义listview的方法。但是,我的listview没有显示任何内容。我正在使用android studio 3.0
CodeforcesContest.java
package com.example.redwanul.cptracker;
/**
* Created by redwanul on 12/1/17.
*/
public class CodeforcesContest {
private String name;
private String time;
public CodeforcesContest(String name, String time) {
this.name = name;
this.time = time;
}
public String getName() {
return name;
}
public String getTime() {
return time;
}
public void setName(String name) { this.name = name; }
public void setTime(String time) { this.time = time; }
}
package com.example.redwanul.cptracker;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import org.json.JSONArray;
import org.json.JSONObject;
import java.util.ArrayList;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link FragmentUpcomingContest.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link FragmentUpcomingContest#newInstance} factory method to
* create an instance of this fragment.
*/
public class FragmentUpcomingContest extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public FragmentUpcomingContest() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment FragmentUpcomingContest.
*/
// TODO: Rename and change types and number of parameters
public static FragmentUpcomingContest newInstance(String param1, String param2) {
FragmentUpcomingContest fragment = new FragmentUpcomingContest();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ArrayList <CodeforcesContest> arrayList = new ArrayList<>();
CodeforcesContest[] contests;
View myLayout = inflater.inflate(R.layout.fragment_fragment_upcoming_contest,container,false);
ListView listView = myLayout.findViewById(R.id.listView);
try {
JSONArray jsonArray = new GetCodeforcesContestList().execute().get();
for(int i = 0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String _name = jsonObject.getString("name");
String _phase = jsonObject.getString("phase");
String _time = jsonObject.getString("startTimeSeconds");
Log.d("Debug: name",_name);
Log.d("Debug: phase",_phase);
Log.d("Debug: Time",_time);
if(_phase.equals(new String("BEFORE"))){
arrayList.add(new CodeforcesContest(_name,_time));
}
}
}
catch (Exception ex){
ex.printStackTrace();
}
contests = new CodeforcesContest[arrayList.size()];
for(int i = 0; i < arrayList.size(); i++){
contests[i] = arrayList.get(i);
}
Log.d("Array Length: ", new Integer(arrayList.size()).toString());
ContestAdapter mAdapter = new ContestAdapter(getContext(),R.layout.row,contests);
listView.setAdapter(mAdapter);
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_fragment_upcoming_contest, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
package com.example.redwanul.cptracker;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
/**
* Created by redwanul on 12/1/17.
*/
public class ContestAdapter extends ArrayAdapter<CodeforcesContest> {
Context context;
int layourResourceId;
private static LayoutInflater inflater = null;
CodeforcesContest[] data = null;
public ContestAdapter(Context context, int layoutResourceId, CodeforcesContest[] data){
super(context,layoutResourceId,data);
this.layourResourceId = layoutResourceId;
this.context = context;
this.data = data;
int ll = data.length;
Log.d("Constructor",new Integer(data.length).toString());
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View vi = convertView;
if(vi == null)
vi = inflater.inflate(R.layout.row,null);
CodeforcesContest contest = data[position];
Log.d("In Adapter",contest.getName());
TextView contestName = (TextView)vi.findViewById(R.id.contest_name);
TextView contestSite = (TextView)vi.findViewById(R.id.contest_site);
TextView timeDate = (TextView)vi.findViewById(R.id.date_time);
Date date = new Date(Integer.parseInt(contest.getTime()) * 1000);
SimpleDateFormat formatter = new SimpleDateFormat("M/D/YYYY");
String dateString = formatter.format(date);
contestName.setText(contest.getName());
contestSite.setText("Codeforces");
timeDate.setText(dateString);
return vi;
}
}
单行的自定义布局
row.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:weightSum="9">
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:id="@+id/contest_name"
android:layout_weight="3"/>
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:id="@+id/contest_site"
android:layout_weight="3"
/>
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:id="@+id/date_time"
android:layout_weight="3"/>
</LinearLayout>
用于显示ListView的片段类
FragmentUpcomingContest.java
package com.example.redwanul.cptracker;
/**
* Created by redwanul on 12/1/17.
*/
public class CodeforcesContest {
private String name;
private String time;
public CodeforcesContest(String name, String time) {
this.name = name;
this.time = time;
}
public String getName() {
return name;
}
public String getTime() {
return time;
}
public void setName(String name) { this.name = name; }
public void setTime(String time) { this.time = time; }
}
package com.example.redwanul.cptracker;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import org.json.JSONArray;
import org.json.JSONObject;
import java.util.ArrayList;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link FragmentUpcomingContest.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link FragmentUpcomingContest#newInstance} factory method to
* create an instance of this fragment.
*/
public class FragmentUpcomingContest extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public FragmentUpcomingContest() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment FragmentUpcomingContest.
*/
// TODO: Rename and change types and number of parameters
public static FragmentUpcomingContest newInstance(String param1, String param2) {
FragmentUpcomingContest fragment = new FragmentUpcomingContest();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ArrayList <CodeforcesContest> arrayList = new ArrayList<>();
CodeforcesContest[] contests;
View myLayout = inflater.inflate(R.layout.fragment_fragment_upcoming_contest,container,false);
ListView listView = myLayout.findViewById(R.id.listView);
try {
JSONArray jsonArray = new GetCodeforcesContestList().execute().get();
for(int i = 0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String _name = jsonObject.getString("name");
String _phase = jsonObject.getString("phase");
String _time = jsonObject.getString("startTimeSeconds");
Log.d("Debug: name",_name);
Log.d("Debug: phase",_phase);
Log.d("Debug: Time",_time);
if(_phase.equals(new String("BEFORE"))){
arrayList.add(new CodeforcesContest(_name,_time));
}
}
}
catch (Exception ex){
ex.printStackTrace();
}
contests = new CodeforcesContest[arrayList.size()];
for(int i = 0; i < arrayList.size(); i++){
contests[i] = arrayList.get(i);
}
Log.d("Array Length: ", new Integer(arrayList.size()).toString());
ContestAdapter mAdapter = new ContestAdapter(getContext(),R.layout.row,contests);
listView.setAdapter(mAdapter);
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_fragment_upcoming_contest, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
package com.example.redwanul.cptracker;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
/**
* Created by redwanul on 12/1/17.
*/
public class ContestAdapter extends ArrayAdapter<CodeforcesContest> {
Context context;
int layourResourceId;
private static LayoutInflater inflater = null;
CodeforcesContest[] data = null;
public ContestAdapter(Context context, int layoutResourceId, CodeforcesContest[] data){
super(context,layoutResourceId,data);
this.layourResourceId = layoutResourceId;
this.context = context;
this.data = data;
int ll = data.length;
Log.d("Constructor",new Integer(data.length).toString());
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View vi = convertView;
if(vi == null)
vi = inflater.inflate(R.layout.row,null);
CodeforcesContest contest = data[position];
Log.d("In Adapter",contest.getName());
TextView contestName = (TextView)vi.findViewById(R.id.contest_name);
TextView contestSite = (TextView)vi.findViewById(R.id.contest_site);
TextView timeDate = (TextView)vi.findViewById(R.id.date_time);
Date date = new Date(Integer.parseInt(contest.getTime()) * 1000);
SimpleDateFormat formatter = new SimpleDateFormat("M/D/YYYY");
String dateString = formatter.format(date);
contestName.setText(contest.getName());
contestSite.setText("Codeforces");
timeDate.setText(dateString);
return vi;
}
}
package com.example.redwanul.cptracker;
导入android.content.Context;
导入android.net.Uri;
导入android.os.Bundle;
导入android.support.v4.app.Fragment;
导入android.util.Log;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.view.ViewGroup;
导入android.widget.ListView;
导入org.json.JSONArray;
导入org.json.JSONObject;
导入java.util.ArrayList;
/**
*一个简单的{@link Fragment}子类。
*包含此片段的活动必须实现
*{@link FragmentUpcomingContest.OnFragmentInteractionListener}接口
*处理交互事件。
*使用{@link FragmentUpcomingContest#newInstance}工厂方法
*创建此片段的实例。
*/
公共类FragmentUpcomingContest扩展了Fragment{
//TODO:重命名参数参数,选择匹配的名称
//片段初始化参数,例如ARG_ITEM_NUMBER
私有静态最终字符串ARG_PARAM1=“PARAM1”;
私有静态最终字符串ARG_PARAM2=“PARAM2”;
//TODO:重命名和更改参数类型
私有字符串mParam1;
私有字符串mParam2;
私有OnFragmentInteractionListener mListener;
公共碎片收集竞赛(){
//必需的空公共构造函数
}
/**
*使用此工厂方法创建的新实例
*使用提供的参数创建此片段。
*
*@param param1参数1。
*@param param2参数2。
*@return FragmentUpcomingContest的新实例。
*/
//TODO:重命名和更改参数的类型和数量
公共静态FragmentUpcomingContest newInstance(字符串param1,字符串param2){
FragmentUpcomingContest fragment=新的FragmentUpcomingContest();
Bundle args=新Bundle();
args.putString(ARG_PARAM1,PARAM1);
args.putString(ARG_PARAM2,PARAM2);
fragment.setArguments(args);
返回片段;
}
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
如果(getArguments()!=null){
mParam1=getArguments().getString(ARG_PARAM1);
mParam2=getArguments().getString(ARG_PARAM2);
}
}
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
ArrayList ArrayList=新的ArrayList();
CodeforcesContest[]竞赛;
查看myLayout=充气机。充气(R.layout.fragment\u fragment\u即将到来的比赛,容器,错误);
ListView ListView=myLayout.findViewById(R.id.ListView);
试一试{
JSONArray JSONArray=新GetCodeforcesContestList().execute().get();
for(int i=0;i