Android ImageAdapter 与 Fragment 中的 Gridview

Posted 2023-04-19

【中文标题】Android ImageAdapter 与 Fragment 中的 Gridview

【英文标题】：Android ImageAdapter with Gridview in Fragment

【发布时间】：2013-10-13 10:09:30

【问题描述】：

我有一个带有 gridview 的适配器，可以作为 Activity 工作。我现在正试图将它放在一个片段中并转换了东西，但它不起作用。当我在我的 Activity 中包含 IconFragmentSystem 时，我在尝试打开 Activity 时会强制关闭。

我知道 Activity 可以正常工作，因为我可以使用其他 Fragments 并且一切正常，所以我知道我的问题出在这个文件中。

package com.designrifts.ultimatethemeui;
import com.designrifts.ultimatethemeui.R;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;

import java.util.ArrayList;

public class IconFragmentSystem extends Fragment implements AdapterView.OnItemClickListener
private static final String RESULT_OK = null;
public Uri CONTENT_URI;

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) 

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

    super.onCreate(savedInstanceState);
    int iconSize=getResources().getDimensionPixelSize(android.R.dimen.app_icon_size);

    GridView gridview = (GridView) getActivity().findViewById(R.id.icon_grid);
    gridview.setAdapter(new IconAdapter(this, iconSize));
    gridview.setOnItemClickListener(this);
    CONTENT_URI=Uri.parse("content://"+iconsProvider.class.getCanonicalName());
    return view;


@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) 
    String icon=adapterView.getItemAtPosition(i).toString();
    Intent result = new Intent(null, Uri.withAppendedPath(CONTENT_URI,icon));
    setResult(RESULT_OK, result);
    finish();

private void setResult(String resultOk, Intent result) 
    // TODO Auto-generated method stub



private void finish() 
    // TODO Auto-generated method stub


private class IconAdapter extends BaseAdapter
    private Context mContext;
    private int mIconSize;
    public IconAdapter(Context mContext, int iconsize) 
        super();
        this.mContext = mContext;
        this.mIconSize = iconsize;
        loadIcon();
    

    public IconAdapter(IconFragmentSystem iconssystem, int iconSize) 
        // TODO Auto-generated constructor stub
    

    @Override
    public int getCount() 
        return mThumbs.size();
    

    @Override
    public Object getItem(int position) 
        return mThumbs.get(position);
    

    @Override
    public long getItemId(int position) 
        return position;
    

    @Override
    public View getView(int position, View convertView, ViewGroup parent) 
        ImageView imageView;
        if (convertView == null) 
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(mIconSize, mIconSize));
         else 
            imageView = (ImageView) convertView;
        
        imageView.setImageResource(mThumbs.get(position));
        return imageView;
    

    private ArrayList<Integer> mThumbs;
    ////////////////////////////////////////////////
    private void loadIcon() 
        mThumbs = new ArrayList<Integer>();

        final Resources resources = getResources();
        final String packageName = getActivity().getApplication().getPackageName();

        addIcon(resources, packageName, R.array.systemicons);

    
    private void addIcon(Resources resources, String packageName, int list) 
        final String[] extras = resources.getStringArray(list);
        for (String extra : extras) 
            int res = resources.getIdentifier(extra, "drawable", packageName);
            if (res != 0) 
                final int thumbRes = resources.getIdentifier(extra,"drawable", packageName);
                if (thumbRes != 0) 
                    mThumbs.add(thumbRes);
                
            
            
           
        
    

我尝试了不同的方法来实现这一点，但都失败了，我真的可以使用帮助为我指明正确的方向。

这是我在布局中的 xml

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_
        android:layout_ >           
  <GridView
    android:id="@+id/gridview"
    android:layout_ 
    android:layout_
    android:columnWidth="90dp"
    android:numColumns="auto_fit"
    android:verticalSpacing="10dp"
    android:horizontalSpacing="10dp"
    android:stretchMode="columnWidth"
    android:gravity="center"
/>

    </RelativeLayout>

【问题讨论】：

LogCat 对此有何评论？

@Ray Stojonic 当我运行 logcat 它给了我'code'10-06 19:10:27.450: E/AndroidRuntime(10180): FATAL EXCEPTION: main 10-06 19:10:27.450: E/AndroidRuntime(10180): java.lang.NullPointerException 10-06 19:10:27.450: E/AndroidRuntime(10180): at com.designrifts.ultimatethemeui.IconFragmentSystem.onCreateView(IconFragmentSystem.java:28) 所以我知道它是从 onCreateView。我查看了示例并阅读了 Android 网站，但没有任何运气。

【参考方案1】：

我能够解决问题

我变了

    GridView gridview = (GridView) getActivity().findViewById(R.id.icon_grid);

到

    GridView gridview = (GridView) view.findViewById(R.id.icon_grid);

我也变了

     gridview.setAdapter(new IconAdapter(this, iconSize));

到

     gridview.setAdapter(new IconAdapter(getActivity(), iconSize));

【参考方案2】：

试试这个。

gridView = (GridView) rootView.findViewById(R.id.gridView);

gridView.setOnItemClickListener(new OnItemClickListener() 

            @Override
            public void onItemClick(AdapterView<?> adapterView, View view,int pos, long l) 

                // do something...

                           
        );

有关详细信息，请参阅此链接： Android gridview in fragment adapter constructor missing

【参考方案3】：

GridView gridview = (GridView) getActivity().findViewById(R.id.icon_grid);

应该是

GridView gridview = (GridView) container.findViewById(R.id.icon_grid);

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

    int iconSize = getResources().getDimensionPixelSize(android.R.dimen.app_icon_size);

    GridView gridview = (GridView) view.findViewById(R.id.icon_grid);
    gridview.setAdapter(new IconAdapter(this, iconSize));
    gridview.setOnItemClickListener(this);
    CONTENT_URI = Uri.parse("content://"+iconsProvider.class.getCanonicalName());
    return view;

您要删除对 super 的调用，这是您活动的剩余部分，片段不调用此方法。

【讨论】：

我添加时仍然遇到同样的错误。我把 logcat 以及工作的代码版本pastebin.com/ByjyURxs 是 logcat。这是来自 Activity github.com/designrifts/Ultimate_Theme_UI_Template/blob/master/…

的工作版本

在oncreateview中也不要调用super

我确实删除了超级。谢谢！