How to save data by using SharedPreferences in a Fragment

问题

1. I'm having a problem with saving data permanently. It should be simple, I'm sending data to another Fragment and it works perfectly, however, I have no idea how to save data.
   I tried something, but I was wondering if you could help me out.

In my code, I'm sending a data to another Fragment by pushing a Button.

2. So this is the code:

   package com.example.mskydraw.notetech;

   import android.content.Context;
   import android.content.SharedPreferences;
   import android.os.Bundle;
   import android.support.v4.app.Fragment;
   import android.support.v4.app.FragmentManager;
   import android.view.LayoutInflater;
   import android.view.View;
   import android.view.ViewGroup;
   import android.widget.Button;
   import android.widget.EditText;
   import android.widget.Gallery;
   import android.widget.TextView;
   import android.widget.Toast;
   
   import java.io.FileOutputStream;
   
   import static android.content.Context.MODE_PRIVATE;
   

/** * A simple {@link Fragment} subclass. */ public class Cofo extends Fragment {

final static String SHARED_NAME_STRING="sharedp";
final static String USER_NAME_STRING="user";




public Cofo() {
    // Required empty public constructor
}

EditText newTxt;
Button newBtn;
SharedPreferences sharedPreferences;
Context c = getActivity();

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_cofo, container, false);
    // finding my bouton and text on layout
    newTxt = (EditText)view.findViewById(R.id.Txt);
    newBtn = (Button)view.findViewById(R.id.Btn);



    sharedPreferences=this.c.getSharedPreferences(SHARED_NAME_STRING,Context.MODE_PRIVATE);
    String userNameString=sharedPreferences.getString(USER_NAME_STRING, "");

    newTxt.setText(userNameString);

    // whenever I click on the bouton
    newBtn.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){


            //This code allows you to jump into another fragment
            // Call the fragment to where I want to jump
            Main_content newmain = new Main_content();

            //Here we are going to learn to how to save data
            String Message = newTxt.getText().toString();
            String file_name = "Hello_file";
            // Create an object output string


            //here we are sending data to another fragment
            //You have declare bundle
            Bundle bundle = new Bundle();
            // You can use bundle.putxx everything such as String...float..
            bundle.putInt("N1",5);
            //calling the fragment I'm going to send the data
            // and I'm going to send data I saved on bundle.
            newmain.setArguments(bundle);
            // The process of declaration fragment
            FragmentManager manager = getFragmentManager();
            // Jumping into main content fragment
            manager.beginTransaction().replace(R.id.fragment,newmain).commit();

            if (newTxt.getText().toString().equals("Hello")){
                Toast.makeText(Cofo.this.getActivity(), "true", Toast.LENGTH_SHORT).show();
            }
            else{
                Toast.makeText(Cofo.this.getActivity(), "Hi", Toast.LENGTH_SHORT).show();
            }

            SharedPreferences.Editor editor=sharedPreferences.edit();



        }
    });

    return view;
}

}

回答1:

If you want to use Shared Preferences instead of sending the data through bundles, use this code:

    String stringToSave = "Save me!";

    // To save data to SP
    SharedPreferences.Editor editor = getContext().getSharedPreferences(SHARED_NAME_STRING, MODE_PRIVATE).edit();
    editor.putString(USER_NAME_STRING, stringToSave);
    editor.apply();

    // To load the data at a later time
    SharedPreferences prefs = getContext().getSharedPreferences(SHARED_NAME_STRING, MODE_PRIVATE);
    String loadedString = prefs.getString(USER_NAME_STRING, null);

This code is setup to work with fragments. If you use an Activity instead, remove getContext() in front of getSharedPreferences().

来源：https://stackoverflow.com/questions/46051658/how-to-save-data-by-using-sharedpreferences-in-a-fragment