Listview内部使用customadapter的可滑动标签片段

【问题标题】：Listview Inside swipeable tabs fragment using customadapterListview内部使用customadapter的可滑动标签片段
【发布时间】：2015-11-21 17:37:44
【问题描述】：

我正在尝试在可滑动标签片段中设置列表视图，但不知何故，数据没有存储在 customlistitem（setter 和 getter 类）中。它总是显示空值。请帮忙

这是tab1片段代码

package com.example.ic071034.materialstabs;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import java.util.ArrayList;


public class Tab1 extends Fragment {

private ListView mListView;
public ListviewContactAdapter adapter;
public ArrayList<ListviewContactItem> listContact;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.tab1, container, false);

    mListView = (ListView) rootView.findViewById(android.R.id.list);

    return rootView;
}
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    listContact = GetlistContact();
    adapter=new ListviewContactAdapter(getActivity(), listContact);
    mListView.setAdapter(adapter);

}
private ArrayList<ListviewContactItem> GetlistContact(){
    ArrayList<ListviewContactItem> contactlist = new ArrayList<>();

    ListviewContactItem contact = new ListviewContactItem();

    contact.setPickUpPoint("xyz");
    contact.setArea("xyz City");
    contact.setLandmark("near xyz");
    contact.setStreetName("xyz Road");
    contactlist.add(contact);


    contact = new ListviewContactItem();
    contact.setPickUpPoint("xyz");
    contact.setArea("xyz City");
    contact.setLandmark("near xyz");
    contact.setStreetName("xyz Road");
    contactlist.add(contact);

    contact = new ListviewContactItem();
    contact.setPickUpPoint("xyz");
    contact.setArea("xyz City");
    contact.setLandmark("near xyz");
    contact.setStreetName("xyz Road");
    contactlist.add(contact);

    return contactlist;
}
}

这是自定义适配器代码

package com.example.ic071034.materialstabs;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.ArrayList;


public class ListviewContactAdapter extends BaseAdapter {
private static ArrayList<ListviewContactItem> listContact=null;

private LayoutInflater mInflater;
private Context context;

public ListviewContactAdapter(Context photosFragment, ArrayList<ListviewContactItem> results){
    listContact = results;
 //   mInflater = LayoutInflater.from(photosFragment);
    this.context=photosFragment;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return listContact.size();
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return listContact.get(arg0);
}

@Override
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return arg0;
}


public View getView(int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    ViewHolder holder;
    LayoutInflater mInflater = (LayoutInflater) context
            .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
    if(convertView == null){
        convertView = mInflater.inflate(R.layout.pickup_point_list_layout, null);
        holder = new ViewHolder();
        holder.txtpickuppoint = (TextView) convertView.findViewById(R.id.rd_header_text);
        holder.txtarea = (TextView) convertView.findViewById(R.id.area);
        holder.txtlandmark = (TextView) convertView.findViewById(R.id.landmark);
        holder.txtstreetname = (TextView) convertView.findViewById(R.id.streetname);

        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    holder.txtpickuppoint.setText(listContact.get(position).getPickUpPoint());
    holder.txtarea.setText(listContact.get(position).getArea());
    holder.txtlandmark.setText(listContact.get(position).getLandmark());
    holder.txtstreetname.setText(listContact.get(position).getStreetName());

    return convertView;
}

static class ViewHolder{
    TextView txtpickuppoint, txtarea,txtlandmark,txtstreetname;
}
}

这是自定义项类

public class ListviewContactItem {

private String PickUpPoint="";
private String Area = "";
private String Landmark="";
private String StreetName="";


//Area
public String getArea() {
    return Area;
}

public void setArea(String Area) {
    this.Area = Area;
}

//landmark
public String getLandmark() {
    return Landmark;
}

public void setLandmark(String Landmark) {
    this.Landmark = Landmark;
}

//PickUpPoint
public void setPickUpPoint(String PickUpPoint) {
    this.PickUpPoint = PickUpPoint;
}

public String getPickUpPoint() {
    return PickUpPoint;
}


//streetname
public void setStreetName(String StreetName) {
    this.StreetName = StreetName;
}

public String getStreetName() {
    return StreetName;
}

}

这里是日志猫

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
        at com.example.ic071034.materialstabs.Tab1.onCreateView(Tab1.java:28)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1016)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1197)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1562)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:535)
        at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1106)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560)
        at android.view.View.measure(View.java:17448)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2031)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1189)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1402)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1077)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5884)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
        at android.view.Choreographer.doCallbacks(Choreographer.java:580)
        at android.view.Choreographer.doFrame(Choreographer.java:550)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5312)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)

还有布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">

<include
    android:id="@+id/tool_bar"
    layout="@layout/tool_bar"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    />

<com.example.ic071034.materialstabs.SlidingTabLayout
    android:id="@+id/tabs"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:elevation="2dp"
    android:background="@color/ColorPrimary"/>

<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:layout_weight="1">
</android.support.v4.view.ViewPager>


</LinearLayout>

标签布局

<?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">

<ListView
    android:id="@+id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />

</LinearLayout>

【问题讨论】：

  • 我认为问题是android.R.id.list，当您为片段声明布局时，您需要在 xml 文件中使用 listView 的 id。你可以发布xml文件吗？
  • 为什么你在mListView中使用android.R.id.list = (ListView) rootView.findViewById(android.R.id.list);您必须使用自己的 R.id.list，该列表肯定不在您的 xml 视图中！
  • 嘿，非常感谢。愚蠢的错误..它现在就像一个魅力。谢谢。

标签： android list fragment


【解决方案1】： 
listContact = GetlistContact();
adapter=new ListviewContactAdapter(getActivity(), listContact);
mListView.setAdapter(adapter);

在 onCreateView 上移动这些行

【讨论】：

  • onViewCreate 优于 onCreateView
  • 不，它不起作用。分配空值仍然会引发错误。
  • 我会将 logcat 添加到问题中
  • 根据你的 logcat.. 你的 listview 本身是空的.. 检查一次
  • 这就是我想知道的。数据应该显示在列表视图中，因为我存储在 arraylist 变量中。但是 arralist 变量本身并没有存储它。我无法追踪原因..
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