Question

public final class ConnectAsync extends AsyncTask<Void, String, String>
{
    private MainActivity mActivity = new MainActivity();
    private TextView mTextView;

    // other codes...

    @Override
    protected void onProgressUpdate(String... params)
    {
        // exception throws in this line
        mTextView = new TextView(mActivity.getApplicationContext());
    }
}

我调用了publishProgress(myString + " five");并希望生成TextView运行时。但NullPointerException抛出。怎么了？

你能解释一下吗？

感谢。

Answer 1

尝试使用活动上下文代替应用程序上下文代码：

public final class ConnectAsync extends AsyncTask<Void, String, String>
{
    private Context context;
    // other codes...

    public ConnectAsync(Context context)
    {
        this.context = context;
    }

    @Override
    protected void onProgressUpdate(String... params)
    {
        // exception throws in this line
        mTextView = new TextView(context);
    }
}

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启动TextView时，在getapplicationContext（）中使用Java.lang.NullPointerException

1 个答案: