Question

我正在研究基于片段的学校项目。我已经制作了XML文件，但我在nearfragment.java中收到错误。你能否告诉我错误的位置，因为我熟悉Activity但不熟悉Fragment。请帮我纠正错误。

near_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context="{relativePackage}.${activityClass}" >

    <ListView
        android:id="@+id/list_li"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" >
    </ListView>

</RelativeLayout>

near_layout_mylist.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="horizontal" >

    <ImageView
        android:id="@+id/icon_list"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:padding="5dp" />

    <LinearLayout android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:id="@+id/item_list"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Medium Text"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="5dp"
            android:padding="2dp"
            android:textColor="#33CC33" />
        <TextView
            android:id="@+id/textView1_list"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            android:layout_marginLeft="10dp"/>
    </LinearLayout>
</LinearLayout>

CustomListNearAdapter.java

import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class CustomListNearAdapter extends ArrayAdapter<String> {

    private final Activity context;
    private final String[] itemname;
    private final Integer[] imgid;

    public CustomListNearAdapter(Activity context, String[] itemname, Integer[] imgid) {
        super(context, R.layout.near_layout_mylist, itemname);
        // TODO Auto-generated constructor stub

        this.context=context;
        this.itemname=itemname;
        this.imgid=imgid;
    }

    public View getView(int position,View view,ViewGroup parent) {
        LayoutInflater inflater=context.getLayoutInflater();
        View rowView=inflater.inflate(R.layout.near_layout_mylist, null,true);

        TextView txtTitle = (TextView) rowView.findViewById(R.id.item_list);
        ImageView imageView = (ImageView) rowView.findViewById(R.id.icon_list);
        TextView extratxt = (TextView) rowView.findViewById(R.id.textView1_list);

        txtTitle.setText(itemname[position]);
        imageView.setImageResource(imgid[position]);
        extratxt.setText("Description "+itemname[position]);
        return rowView;

    };
}

NearFragment

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.GridView;
import android.widget.ListView;

/**
 * Created by Ratan on 7/29/2015.
 */
public class NearFragment extends Fragment {



    ListView list;
    String[] itemname ={
            "Safari",
            "Camera",
            "Global",
            "FireFox",
            "UC Browser",
            "Android Folder",
            "VLC Player",
            "Cold War"
    };

    Integer[] imgid={
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
            R.drawable.akash,
    };

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        View view = inflater.inflate(R.layout.near_layout, container,false);
        CustomListNearAdapter adapter=new CustomListNearAdapter(this, itemname, imgid);

        ListView listView = (ListView) view.findViewById(R.id.list_item);
        listView.setAdapter(new CustomListNearAdapter(getActivity()));
        return view;


    }


}

错误在于nearfragment，我无法为Fragment编写代码。所以请给我一些指示。

Answer 1

在您的代码中，在设置adapter时，您没有将正确的值传递给构造函数，意味着在您的代码中的行。

listView.setAdapter(new CustomListNearAdapter(getActivity()));

在上面的行中有问题，所以用下面的代码行替换代码。

        CustomListNearAdapter adapter=new CustomListNearAdapter(getActivity(), itemname, imgid);

        ListView listView = (ListView) view.findViewById(R.id.list_li);
        listView.setAdapter(adapter);

Answer 2

在下面的行中使用 getActivity（）而不是这个

CustomListNearAdapter adapter=new CustomListNearAdapter(this, itemname, imgid);

并将适配器设置为listview，如bellow

listView.setAdapter(adapter);

Answer 3

我建议您在加载活动后编写ListView的代码。所以让你的代码如下：

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.near_layout, container, false);
    return view;
}

public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    CustomListNearAdapter adapter=new CustomListNearAdapter(getActivity(), itemname, imgid);
    ListView listView = (ListView) view.findViewById(R.id.list_item);
    listView.setAdapter(new CustomListNearAdapter(getActivity()));
}

由于尚未创建活动，getActivity()可能会导致此处出现问题。此外，您没有正确初始化适配器。您未提供所有值。

Answer 4

像这样重新调整你的代码。

 View view = inflater.inflate(R.layout.near_layout, container,false);

    ListView listView = (ListView) view.findViewById(R.id.list_item);
    listView.setAdapter(new CustomListNearAdapter(getActivity(), itemname, imgid));
    return view;

带有Fragment的Android ListView

4 个答案: