使用时getApplicationContext（）抛出一个异常 [英] getApplicationContext() throws an exception when used

问题描述

我指定一个类的基础上，另一位在现有的Andr​​oid项目。该addRow（）方法应该是动态添加行到表中。 当创建一个新的TextView创建行时添加到我行也，我应该指定背景。目前的办法，试图getApplicationContext（）抛出了一个NullPointerException异常。 那么，我应该得到这方面？

 公共类DistanceTableView扩展ContactListActivity
{
    公共无效addRow（LocationMessage locationMsg）{
        查看消息查看= theInflater.inflate（R.layout.homepage，NULL）;
        TableLayout表=（TableLayout）messageView.findViewById（R.id.distanceTable）;

        TextView的senderNameTextView =新的TextView（getApplicationContext（））;
        senderNameTextView.setText（locationMsg.getSenderName（））;

        的TableRow TR =新的TableRow（getApplicationContext（））;
        tr.addView（distanceTextView）;
        table.addView（TR）;

        rows.addFirst（消息查看）;
    }
}
 

这是我的观点是扩展类：

 公共类ContactListActivity扩展MapActivity工具
        ConnectionListener {}
 

解决方案

我想你有上下文传递到您的类的构造函数。

I've specified a class, based on another one in an existing Android project. The addRow() method is supposed to dynamically add rows to a table. When creating a new TextView to add to my row and also when creating that row, I'm supposed to specify the "context". The current way, trying "getApplicationContext()" throws a NullPointerException. So where am I supposed to get that context from?

public class DistanceTableView extends ContactListActivity
{
    public void addRow(LocationMessage locationMsg){
        View messageView = theInflater.inflate(R.layout.homepage, null);
        TableLayout table = (TableLayout)messageView.findViewById(R.id.distanceTable);

        TextView senderNameTextView = new TextView(getApplicationContext());
        senderNameTextView.setText(locationMsg.getSenderName());

        TableRow tr = new TableRow(getApplicationContext());
        tr.addView(distanceTextView);
        table.addView(tr);

        rows.addFirst(messageView);
    }
}

The class that my view is extending:

public class ContactListActivity extends MapActivity implements
        ConnectionListener {}

解决方案

I guess you have to pass the context to the constructor of your class.

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