在RecyclerView中遇到onClickListener问题[重复]

Posted 2021-03-26

这个问题在这里已有答案：

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• Intent fails because of Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName() 2回答
• RecyclerView onClickListener Doesn't Work 2回答
• Intent is not working in my RecyclerView 4个答案
• What is a NullPointerException, and how do I fix it? 12个答案

我只是添加了一个意图，以便我可以在点击回收器视图中存在的项目之一时转到下一页，但是我在那里收到错误，我也点击了添加Toast消息og项目，这工作正常但意图是崩溃的应用程序。而且我在适配器中添加此代码而不是在主活动中。需要一些帮助，谢谢

public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, final int position) {
        if (holder instanceof ItemViewHolder) {
            final Notifications notification = notifications.get(position);
            final ItemViewHolder viewHolder = (ItemViewHolder) holder;
            viewHolder.title.setText(notifications.get(position).getTitle());
            viewHolder.description.setText(notifications.get(position).getDescription());
            viewHolder.date.setText(notifications.get(position).getDate());
            viewHolder.itemView.setBackgroundColor(Color.GRAY);

            viewHolder.notificationLay.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Toast.makeText((firebaseMain)activity, "Item clicked " + position, Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(firebaseMainActivity, NotificationDetails.class);
                    context.startActivity(intent);
                }
            });
        } else if (holder instanceof LoadingViewHolder) {
            LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
            loadingViewHolder.progressBar.setIndeterminate(true);
        }

    }

E/androidRuntime: FATAL EXCEPTION: main
    Process: com.app.sample.collegeautomation, PID: 1875
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
        at android.content.ComponentName.<init>(ComponentName.java:130)
        at android.content.Intent.<init>(Intent.java:6082)
        at com.app.sample.collegeautomation.firebaseNotifications.firebaseListViewAdapter$3.onClick(firebaseListViewAdapter.java:146)
        at android.view.View.performClick(View.java:6597)
        at com.balysv.materialripple.MaterialRippleLayout$PerformClickEvent.run(MaterialRippleLayout.java:648)
        at com.balysv.materialripple.MaterialRippleLayout$3.onAnimationEnd(MaterialRippleLayout.java:336)
        at android.animation.Animator$AnimatorListener.onAnimationEnd(Animator.java:552)
        at android.animation.AnimatorSet.endAnimation(AnimatorSet.java:1294)
        at android.animation.AnimatorSet.doAnimationFrame(AnimatorSet.java:1079)
        at android.animation.AnimationHandler.doAnimationFrame(AnimationHandler.java:146)

答案

**create the constrtuctor of the adapter class and pass context**

public UserListAdapter(Context context, int resource,List<UserListDataModel> objects) {
    super(context, resource, objects);
    this.ctx = context;
}
**now in Intent pass this ctx**

Intent intent = new Intent(ctx,AlarmDispositonActivity.class);
    intent.putExtras(bundle);