分離片段代碼和MainActivity代碼

Question

我不擅長Android，我在學習階段。 這是我的問題。 下面的函數是MainActivity.class

public void callReportsFragment(int position) { 
    ReportsFragment cFragment = new ReportsFragment(); 
    Bundle data = new Bundle(); 
    data.putInt("position", position); 

    // Setting the position to the fragment 
    cFragment.setArguments(data); 
    // 
    FragmentManager fragmentManager = getFragmentManager(); 

    // Creating a fragment transaction 
    FragmentTransaction ft = fragmentManager.beginTransaction(); 

    // Adding a fragment to the fragment transaction 
    ft.replace(R.id.content_frame, cFragment); 

    // Committing the transaction 
    ft.commit(); 

} 

之下，以下是我的ReportsFragment類。

package com.example.reports; 

import android.os.Bundle; 

import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
import android.app.Fragment; 




public class ReportsFragment extends Fragment{ 


    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
    Bundle savedInstanceState) { 

     // Retrieving the currently selected item number 
     int position = getArguments().getInt("position"); 

     // List of option 
     String[] options = getResources().getStringArray(R.array.sidebar1); 

     // Creating view correspoding to the fragment 
     View v = inflater.inflate(R.layout.fragment_layout, container, false); 

     // Getting reference to the TextView of the Fragment 
     TextView tv = (TextView) v.findViewById(R.id.tv_content); 

     // Setting currently selected option name in the TextView 
     tv.setText(options[position]); 

     return v; 
    } 
} 

應用程序工作正常。但我想要callReportsFragment(int position)看起來像下面;

public void callReportsFragment(int position) { 
    ReportsFragment cFragment = new ReportsFragment(); 
    cFragment.fetchReportView(position); 
} 

並使ReportsFragment類中的fetchReportView方法，根據我看起來像這樣。

public class ReportsFragment extends Fragment { 


    @ 
    Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
     Bundle savedInstanceState) { 

     // Retrieving the currently selected item number 
     int position = getArguments().getInt("position"); 

     // List of option 
     String[] options = getResources().getStringArray(R.array.sidebar1); 

     // Creating view correspoding to the fragment 
     View v = inflater.inflate(R.layout.fragment_layout, container, false); 

     // Getting reference to the TextView of the Fragment 
     TextView tv = (TextView) v.findViewById(R.id.tv_content); 

     // Setting currently selected option name in the TextView 
     tv.setText(options[position]); 

     return v; 
    } 

    public void fetchReportView(int pos) { 

     Bundle data = new Bundle(); 
     data.putInt("position", pos); 


     this.setArguments(data); 

     FragmentManager fragmentManager = getFragmentManager(); 


     FragmentTransaction ft = fragmentManager.beginTransaction(); 

     // Adding a fragment to the fragment transaction 
     ft.replace(R.id.content_frame, this); 

     // Committing the transaction 
     ft.commit(); 

    } 

} 

請幫我做到這一點。我的動機是保持代碼分離。

Answer 1

您可以在ReportsFragment類中創建公共靜態方法，該方法將返回使用特定參數準備的片段的新實例。但是你應該只在你的活動中使用你的FragmentManager。

Answer 2

如果此片段尚未附加到任何活動，則從片段內調用getFragmentManager()或getActivity()將始終返回空值。 在Android中使用你想達到什麼樣的正確的模式是具有靜態公共方法，在該片段中，像這樣：

public static ReportsFragment newInstance(int position) { 
    Bundle data = new Bundle(); 
    data.putInt("position", position); 
    ReportsFragment fragment = new ReportsFragment(); 
    fragment.setArguments(data); 
    return fragment; 
} 

，然後從託管活動電話： getFragmentManager().beginTransaction().replace(R.id.content_frame, ReportsFragment.newInstance(position)).commit();