从 BaseAdapter 访问 Activity 的变量

Question

我想从 BaseAdapter class 中的 activity 访问一个变量，我用它设置了 activity 的 ListView。但我总是得到这个错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Integer.toString()' on a null object reference

这些是我的代码的相关部分：

public class GetAllEntrysListViewAdapter extends BaseAdapter {

Integer markerID;
PinboardActivity pinboard = new PinboardActivity();

public GetAllEntrysListViewAdapter(JSONArray jsonArray, Context context) {
    this.dataArray = jsonArray;
    this.context= context;
    //I want to get the markerID variable from pinboardActivity:
    markerID = pinboard.markerID;
    inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
//...
public Cursor getLikes(DbHelper dbh) {
    //The following line is the one the error occurs
    String args[] = {markerID.toString(), pos};
    //...
}

Answer 1

那是因为markerID是null.
检查您的下一行

//I want to get the markerID variable from pinboardActivity:
    markerID = pinboard.markerID;

此处 pinboard.markerID 返回空对象。

从 BaseAdapter 访问 Activity 的变量

Access Variable of Activity from BaseAdapter

java

android

baseadapter