如何在没有活动的类中使用getContentResolver? [英] how use getContentResolver in a class without activity?

问题描述

我的课看起来像这样:

public class sendInformation{

  public void test() throws Exception {
    Uri uri = SuspiciousActivityTable.CONTENT_URI;
    getContentResolver().update(uri, values2, where,new String[]{"Null"});
    }
  }
}

但是它说 getContentResolver()不存在，我知道我需要一个Context或Activity来完成这项工作，但是如何在这里获取正确的Context?

but it say getContentResolver() doesn't exist, I know I need a Context or Activity to make this work but how do I get the correct Context here?

推荐答案

您将需要传递一个Context，甚至是

You will need to pass off a Context, even the ContentResolver class needs a valid context to be instantiated.

最简单的方法是将该方法作为参数:

Simplest way is as an argument to the method:

public void test(Context context) throws Exception {
    Uri uri = SuspiciousActivityTable.CONTENT_URI;
    context.getContentResolver().update(uri, values2, where,new String[]{"Null"});
  }

然后调用:(假设包含 test 的类被实例化 ，并且您的Activity的名称为 MyActivity <-替换为您正在调用的活动名称 test() from )

And to call: (assuming that the class that contains test is instantiated and your Activity's name is MyActivity <- Replace with the Activity name you're calling test() from)

try{
    sendInformationInstanceVariable.test (MyActivity.this);
}
catch (Exception e)
{
 e.printStackTrace();
}

MyActivity.this 可以简化为 this ，如果您不是从以下位置调用 test()在一个匿名内部类中.

MyActivity.this can be shortened to just this if you're not calling test() from inside an anonymous inner class.

此外，如果您的类确实没有充分的理由要实例化，请考虑将 test()设为 static 方法，如下所示:

Also, if your class really doesn't have a good reason to be instantiated, consider making test() a static method, like this:

public static void test(Context context) throws Exception {
        Uri uri = SuspiciousActivityTable.CONTENT_URI;
        context.getContentResolver().update(uri, values2, where,new String[]{"Null"});
      }

然后从您的 Activity 中调用该方法，而无需实例:

Then from your Activity, you call this method without needing an instance:

try{
    sendInformation.test (MyActivity.this);
}
catch (Exception e)
{
 e.printStackTrace();
}

最后，抛出 Exception 是不好的做法，不要没有充分的理由就不要这样做，如果确实有充分的理由，请尽可能具体.

Lastly, throwing Exception is bad practice, do don't do it without good reason and if you do have a good reason, be as specific as possible.

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