java - 从 FirebaseRecyclerAdapter 获取文档 ID 并将值传递到新页面
问题描述
我有一个显示文档列表的 FirestoreRecyclerAdapter。我在列表中的每个项目旁边都有一个按钮。单击此按钮时,我想获取所选项目的唯一 ID,然后将用户带到显示该项目的个人详细信息的页面。
本质上,我想将单击的文档的 ID 传递到下一页。但是,我的按钮在单击时会引发空指针异常。
这段代码来自我的 ClubAdapter 类。
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);
}
}
}
我不断收到错误,
Intent i = new Intent(context, ViewSingleClub.class);
我认为这可能与我的上下文变量引用自身有关,但也不确定我是否正确获取了 ID。有人能帮忙吗?
这是我的错误:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.marykate.marykatefordefyp, PID: 2718
java.lang.NullPointerException
at android.content.ComponentName.<init>(ComponentName.java:77)
at android.content.Intent.<init>(Intent.java:3842)
at com.example.marykate.marykatefordefyp.ClubAdapter1$1.onClick(ClubAdapter1.java:36)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5336)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:681)
at dalvik.system.NativeStart.main(Native Method)
解决方案
这是因为您正在分配“自身的上下文”。从初始化适配器的类中传递上下文。
假设我有名为“ClubAdapter”的适配器和名为“ClubClass”的调用类
在俱乐部类:
ClubAdapter clubAdapter = new ClubAdapter(list, context);
// if you'r calling it from activity then pass "Activity.this" and if fragment then "getContext()" as context.
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;
}
}
}
或者你可以制作这样的界面。
public interface RecycleViewOnItemClickListener {
void onItemClick(int position);
}
并将其从调用类传递给您的适配器。
假设我有名为“SampleAdapter”的适配器并调用名为“SampleClass”的类在“SampleClass”中,您可以将适配器中的接口作为参数传递。
SampleAdapter sampleAdapter = new SampleAdapter(list, new RecycleViewOnItemClickListener() {
@Override
public void onItemClick(int position) {
// do what you want to perform
}
});
在“俱乐部适配器”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());
}
});
}
}
}
推荐阅读
- windows - ExAllocatePool2 未定义?
- spring-boot - java.lang.AssertionError:预期状态:200 实际:500
- java - 无法以反应方式在 webflux 中返回请求
- amazon-web-services - 如何在 Codebuild 中使用自定义 docker 镜像 node:16.13.0-alpine
- c# - EF Core 全局查询过滤器复杂表达式
- discord.py - 在后台任务中从 json 文件中获取新的频道 ID
- function - 某处有内部公式吗?
- node.js - 带有 where 子句的 node.js firestore 删除
- dagster - 是否可以使用 Dagster 创建动态工作?
- docker-compose - docker-compose 生成名称末尾的 -1 是什么意思