如何使用 Glide 向 RecyclerView 显示图像？

Question

我有用于图像的 Sqlite 数据库，但它只存储 URL，我希望 glide 处理该 URL 以显示图像，

案例：我需要使用 glide 显示图像 url 从 sqlite 到 recycleview。

我之所以使用此代码，是因为它让我想到的不仅仅是将数据从字节解析为图像或其他任何内容。

请帮忙，现在我收到错误“Java.lang.nullPointerException”

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ListViewHolder> {

    private Context mContext;

    private List<Produk> listList = new ArrayList<>();

    public ListAdapter(List<Produk> listList){

        this.listList = listList;
        this.mContext = mContext;
    }

    @Override
    public ListAdapter.ListViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_list ,parent, false);

        ListViewHolder ListViewHolder = new ListViewHolder(view);
        return ListViewHolder;
    }

    @Override
    public void onBindViewHolder(ListAdapter.ListViewHolder holder, int position) {

        holder.txt_rKode.setText((listList.get(position).getKd_produk()));
        holder.txt_rNama.setText(listList.get(position).getNama_produk());
        holder.txt_rMerk.setText(listList.get(position).getMerk_produk());
        holder.txt_rJenis.setText(listList.get(position).getJenis_produk());
        holder.txt_rVariasi.setText(listList.get(position).getVariasi_produk());
        holder.txt_rFoto2.setText(listList.get(position).getFoto_produk());

        String currentUrl = listList.get(position).getFoto_produk();

        Glide.with(mContext)
                .load(currentUrl)
                .into(holder.iv_rFoto);




    }

    @Override
    public int getItemCount() {
        return listList.size();
    }

    public Produk getItem(int Position) {
        return listList.get(Position);
    }

错误日志

这是错误日志。

01-31 14:49:58.795 12577-12577/? E/AndroidRuntime: FATAL EXCEPTION: main
   Process: ptacs.ekatalog.com.e_katalogproduk, PID: 12577
   java.lang.NullPointerException: You cannot start a load on a not yet attached View or a Fragment where getActivity() returns null (which usually occurs when getActivity() is called before the Fragment is attached or after the Fragment is destroyed).
       at com.bumptech.glide.util.Preconditions.checkNotNull(Preconditions.java:31)
       at com.bumptech.glide.Glide.getRetriever(Glide.java:665)
       at com.bumptech.glide.Glide.with(Glide.java:697)
       at ptacs.ekatalog.com.e_katalogproduk.adapter.ListAdapter.onBindViewHolder(ListAdapter.java:56)
       at ptacs.ekatalog.com.e_katalogproduk.adapter.ListAdapter.onBindViewHolder(ListAdapter.java:23)
       at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6482)
       at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6515)
       at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5458)
       at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5724)
       at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5563)
       at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5559)
       at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2229)
       at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1556)
       at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1516)
       at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:608)
       at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3693)
       at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3410)
       at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3962)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:610)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
       at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
       at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:132)
       at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
       at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1361)
       at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:869)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
       at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
       at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
       at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
       at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
       at android.view.View.layout(View.java:15604)
       at android.view.ViewGroup.layout(ViewGroup.java:4968)
       at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
       at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
       at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
       at android.view.View.layout(View.java:15604)
    at android.view.View

Answer 1

我觉得this.mContext = mContext;有问题，可能mContext是null，所以你可以这样写

public ListAdapter(List<Produk> listList,Context mContext){
        this.listList = listList;
        this.mContext = mContext;
    }

确认mContext

Answer 2

首先在您的onCreateViewHolder 中，修复此行：

ListViewHolder ListViewHolder = new ListViewHolder(view);
return ListViewHolder;

到：

return new ListViewHolder(view);

然后在onBindViewHolder 中获取如下URI：

String currentUrl = listList.get(position).getFoto_produk();

Uri uri = Uri.Parse(currentUrl);

Glide.with(mContext).load(uri).into(holder.iv_rFoto);

希望对您有所帮助，同时检查您的 getFoto_produk 字符串值是否正确。 在将 Adapter 设置为 recyclerview 之前，您需要确定此字符串的值

Answer 3

你可以试试下面的代码滑行。

//Glide to load images from url 
if(currentUrl!=null) { 

    //Check whether the url is null   
    Glide.with(mContext)
        .load(currentUrl)//Pass url to be appended
        .asBitmap()
        .fitCenter()
        .diskCacheStrategy(DiskCacheStrategy.SOURCE)
        .placeholder(ContextCompat.getDrawable(mContext, R.drawable.ic_dummy_user))
        .error(ContextCompat.getDrawable(mContext, R.drawable.ic_dummy_user))
        .into(new SimpleTarget<Bitmap>() {

            @Override
            public void onResourceReady(Bitmap bitmapp, GlideAnimation<? super Bitmap> glideAnimation) {
                mMarkerImageView.setImageBitmap(bitmap);
            }
        });
}

Answer 4

由于您的 mContext 为空，您需要将您的上下文传递给 Adapter 类 通常适配器类是纯java类没有上下文。

每当您调用 Adapter 时，您必须从 Fragment 或 Activity 传递您的上下文。

首先，在你的适配器中这样初始化。

public ListAdapter(List<Produk> listList, Context mContext){
    this.listList = listList;
    this.mContext = mContext;
}

如果你从 Fragment 调用适配器然后这样做

ListAdapter listAdapter = new ListAdapter(listList, getActivity());

如果你从活动中调用适配器，那么就这样做

ListAdapter listAdapter = new ListAdapter(listList, YourActivity.this);

祝你好运，请告诉我。