尝试不重复自己（android / java）

Question

这是怎么回事？ 我是开发的初学者，在任何地方我读到“不要重复自己”，所以我真的很想重复自己。 我在应用程序的每个活动中复制并粘贴了一段代码，我怀疑可能有一种不重复的代码-可能创建一个类并调用其方法-但我不知道如何实现它。 下面的代码就是我在说的：我在导航抽屉中使用的东西，它在我的应用程序的每个活动的主类中：

@Override
        public void onItemClick(AdapterView<?> parent, View arg1, int position,
                long arg3) {

            if (position == 0) {
                Toast.makeText(this, "categories baby", Toast.LENGTH_SHORT).show();
            } else if (position == 1){

                final Context context = this;

                Intent getUserData = getIntent();
                String userEmail = getUserData.getStringExtra("user_email");

                Intent intent = new Intent(context, NewAdActivity.class);
                intent.putExtra("userEmail", userEmail);
                startActivity(intent);


            } else if (position == 2){

                final Context context = this;

                Intent getUserData = getIntent();
                String userEmail = getUserData.getStringExtra("user_email");

                Intent intent = new Intent(context, AdListActivity.class);
                intent.putExtra("userEmail", userEmail);
                startActivity(intent);

            } else {
                Session session = Session.getActiveSession();
                session.closeAndClearTokenInformation();

                Intent intent = new Intent(context, MainActivity.class);
                startActivity(intent);
            }
        }

您能给我一些关于如何重用它而不是复制/粘贴的提示吗？ 谢谢！

Answer 1

您可以创建一个扩展Activity并实现您的代码的新类，然后使所有活动都对该类进行扩展。

该代码似乎是AdapterView.OnItemClickListener的实现，因此您可以创建类似以下内容的代码：

public abstract class MyActivityWithListener extends Activity 
        implements AdapterView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView<?> parent, View arg1, int position, long arg3) {
        ....
    }

}

然后您的主要活动可能是这样的：

public class MainActivity extends MyActivityWithListener {
    ...
}

Answer 2

如您在以下块中清楚看到的

        } else if (position == 1){

            final Context context = this;

            Intent getUserData = getIntent();
            String userEmail = getUserData.getStringExtra("user_email");

            Intent intent = new Intent(context, NewAdActivity.class);
            intent.putExtra("userEmail", userEmail);
            startActivity(intent);


        } else if (position == 2){

            final Context context = this;

            Intent getUserData = getIntent();
            String userEmail = getUserData.getStringExtra("user_email");

            Intent intent = new Intent(context, AdListActivity.class);
            intent.putExtra("userEmail", userEmail);
            startActivity(intent);

        }

除了活动的类，您执行了两次相同的操作。 因此，您可以将其分解为如下功能：

        } else if (position == 1){
            beginAdActivity(NewAdActivity.class);
        } else if (position == 2){
            beginAdActivity(AdListActivity.class);
        }
 }

 public void beginAdActivity(Class<?> activityClass)
 {
      final Context context = this;

      Intent getUserData = getIntent();
      String userEmail = getUserData.getStringExtra("user_email");

      Intent intent = new Intent(context, activityClass);
      intent.putExtra("userEmail", userEmail);
      startActivity(intent);
 }

ta-dah，它只被写下一次。

Answer 3

像这样创建一个util类

public class MyUtils{

    public static void jumpToNewAd(Activity mContext){
        Intent getUserData = mContext.getIntent();
        String userEmail = getUserData.getStringExtra("user_email");

        Intent intent = new Intent(mContext, NewAdActivity.class);
        intent.putExtra("userEmail", userEmail);
        mContext.startActivity(intent);
    }
    public static void jumpToAdList(Activity mContext){
        Intent getUserData = mContext.getIntent();
        String userEmail = getUserData.getStringExtra("user_email");

        Intent intent = new Intent(mContext, AdListActivity.class);
        intent.putExtra("userEmail", userEmail);
        mContext.startActivity(intent);
    }
    public static void jumpToMain(Activity mContext){
        Session session = Session.getActiveSession();
        session.closeAndClearTokenInformation();

        Intent intent = new Intent(mContext, MainActivity.class);
        mContext.startActivity(intent);
    }

    public static void ting(Activity mContext,String message){
        Toast.makeText(mContext, message, Toast.LENGTH_SHORT).show();
    }

}

随时随地呼叫

MyUtils.jumpToAdList(this);
        MyUtils.jumpToNewAd(this);
        MyUtils.jumpToMain(this);
        MyUtils.ting(this,"Catagories Baby");