Android 应用程序在创建打开 Intent 时崩溃

Question

当我尝试打开“ReadActivity”时，我的 Android 应用“电子邮件”崩溃。

在 MainActivity 中声明的方法 OpenMail() 应该启动 ReadActivity：

public void OpenMail(View v, int index) {
    String[] mail = {"x", "y", "z"};

    Intent readIntent = new Intent(this, ReadActivity.class); <-- Error occurs here

    readIntent.putExtra("mail", mail);

    startActivity(readIntent);
}

方法在ListViewAdapter中被调用：

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    Holder holder = new Holder();

    View rowView = inflater.inflate(R.layout.listview_item, null);

    holder.imageView = (ImageView) rowView.findViewById(R.id.imageView);
    holder.txvSenderMail = (TextView) rowView.findViewById(R.id.txvSender);
    holder.txvSubject = (TextView) rowView.findViewById(R.id.txvSubject);

    holder.imageView.setImageResource(ImageID[position]);
    holder.txvSenderMail.setText(SenderMail[position]);
    holder.txvSubject.setText(Subject[position]);

    rowView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new MainActivity().OpenMail(v, position);
        }
    });

    return rowView;
}

错误：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()'

我希望有人可以帮助我！ 谢谢！

Answer 1

当你这样做时，你实际上是在尝试创建新的 MainActivity

new MainActivity().OpenMail(v, context, position);

如果你目前在 MainActivity 课上，我想你想做这样的事情：

getActivity().OpenMail(v, context, position);

当然，别忘了将ReadActivity添加到AndroidManifest