我有一個顯示文檔列表的 FirestoreRecyclerAdapter。我在列表中的每個項目旁邊都有一個按鈕。單擊此按鈕時，我想獲取所選項目的唯一 ID，然后將用戶帶到顯示該項目的個人詳細信息的頁面。本質上，我想將單擊的文檔的 ID 傳遞到下一頁。但是，我的按鈕在單擊時會引發空指針異常。這段代碼來自我的 ClubAdapter 類。public class ClubAdapter1 extends FirestoreRecyclerAdapter<Club, ClubAdapter1.ClubHolder> { private String clubId; private Context context; public ClubAdapter1(@NonNull FirestoreRecyclerOptions<Club> options) { super(options); } @Override protected void onBindViewHolder(@NonNull ClubHolder holder, int position, @NonNull Club model) { holder.lblName.setText(model.getClubName()); //getting the ID of the particular event clicked clubId = getSnapshots().getSnapshot(position).getId(); holder.btnDetails.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent i = new Intent(context, ViewSingleClub.class); i.putExtra("id", clubId); context.startActivity(i); } }); } @NonNull @Override public ClubHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) { View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.clublist_layout, parent, false); return new ClubHolder(v); } class ClubHolder extends RecyclerView.ViewHolder { TextView lblName; Button btnDetails; public ClubHolder(@NonNull View itemView) { super(itemView); lblName = itemView.findViewById(R.id.lblName); btnDetails = itemView.findViewById(R.id.btnDetails); } }}我不斷收到錯誤， Intent i = new Intent(context, ViewSingleClub.class); 我認為這可能與我的上下文變量引用自身有關，但也不確定我是否正確獲取了 ID。有人能幫忙嗎？
2 回答
白衣染霜花
TA貢獻1796條經驗 獲得超10個贊
這是因為您正在分配“自身的上下文”。從初始化適配器的類中傳遞上下文。
假設我有名為“ClubAdapter”的適配器和名為“ClubClass”的調用類
在俱樂部類：
ClubAdapter clubAdapter = new ClubAdapter(list, context);
// if you'r calling it from activity then pass "Activity.this" and if fragment then "getContext()" as context.
并在 ClubAdapter
public class ClubAdapter extends RecyclerView.Adapter<ClubAdapter.ClubHolder> {
private Context context;
private List<String> list;
public ClubAdapter(List<String> list, Context context) {
this.list = list;
this.context = context;
}
@NonNull
@Override
public ClubHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.item_sample, viewGroup, false);
return new ClubHolder(itemView, context);
}
public class ClubHolder extends RecyclerView.ViewHolder {
private Context context;
private ClunHolder(@NonNull View itemView,Context context) {
super(itemView);
this.context = context;
}
}
}
或者你可以制作這樣的界面。
public interface RecycleViewOnItemClickListener {
void onItemClick(int position);
}
并將其從調用類傳遞給您的適配器。
假設我有名為“SampleAdapter”的適配器并調用名為“SampleClass”的類在“SampleClass”中，您可以將適配器中的接口作為參數傳遞。
SampleAdapter sampleAdapter = new SampleAdapter(list, new RecycleViewOnItemClickListener() {
@Override
public void onItemClick(int position) {
// do what you want to perform
}
});
在“俱樂部適配器”中
public class ClubAdapter extends RecyclerView.Adapter<ClubAdapter.ClubHolder> {
private RecycleViewOnItemClickListener recycleViewOnItemClickListener;
private List<String> list;
public ClubAdapter(List<String> list, RecycleViewOnItemClickListener recycleViewOnItemClickListener) {
this.list = list;
this.recycleViewOnItemClickListener = recycleViewOnItemClickListener;
}
@NonNull
@Override
public ClubHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.item_sample, viewGroup, false);
return new ClubHolder(itemView, recycleViewOnItemClickListener);
}
public class ClubHolder extends RecyclerView.ViewHolder {
private RecycleViewOnItemClickListener recycleViewOnItemClickListener;
private ClunHolder(@NonNull View itemView,RecycleViewOnItemClickListener recycleViewOnItemClickListener) {
super(itemView);
this.recycleViewOnItemClickListener = recycleViewOnItemClickListener;
//you can callback onItemClick method from here on button click event so it give callback in "ClubActivity".
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
recycleViewOnItemClickListener.onItemClick(getAdapterPosition());
}
});
}
}
}
慕的地6264312
TA貢獻1817條經驗 獲得超6個贊
要解決此問題，請在方法中移動以下代碼行，onBindViewHolder()如下所示：
holder.btnDetails.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(context, ViewSingleClub.class);
i.putExtra("id", clubId);
context.startActivity(i);
}
});
看，我在holder.btnDetails.
編輯：
根據您的意見，還請進行以下操作。將構造函數更改為：
public ClubAdapter1(@NonNull FirestoreRecyclerOptions<Club> options, Context context) {
super(options);
this.context = context;
}
當您在活動中創建適配器類的對象時，還將 傳遞context給構造函數。
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