Question

我在Mainactivity上使用以下代码将用户名存储为AlertDialog中的字符串。

但是，我想使用SharedPreferences或任何方法（如果有的话）存储用户名，当用户打开应用程序时，最初存储的用户名将首先显示。

  private void request_user_name() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Enter name:");

        final EditText input_field = new EditText(this);
        String e  = input_field.getText().toString();

        builder.setView(input_field);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {


                  name = input_field.getText().toString();
            }
        });

        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                dialogInterface.cancel();
                request_user_name();
            }
        });

        builder.show();
    }

我使用了像下面这样的共享Prefrences，但它不起作用

  private void request_user_name() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Enter name:");

        final EditText input_field = new EditText(this);
        String e  = input_field.getText().toString();
        SharedPreferences.Editor editor = sharedpreferences.edit();
        editor.putString(username, e);
        editor.commit();
        builder.setView(input_field);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {


                  name = input_field.getText().toString();
            }
        });

        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                dialogInterface.cancel();
                request_user_name();
            }
        });

        builder.show();
    }

以下是首次初始化应用时的图片

我的整个Mainactivity文件是

package com.nepalpolice.mnemonics.chat;

import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.nepalpolice.mnemonics.R;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;



public class MainActivity extends AppCompatActivity {

    private Button  add_room;
    private EditText room_name;
    EditText edittext;
    private Toolbar mainToolbar;
    public static final String MyPREFERENCES = "MyPrefs" ;
    public static final String username = "userKey";
    ProgressBar progressBar;
    private ListView listView;
    private ArrayAdapter<String> arrayAdapter;
    private ArrayList<String> list_of_rooms = new ArrayList<>();
    private String name;
    private DatabaseReference root = FirebaseDatabase.getInstance().getReference().getRoot();
    SharedPreferences sharedpreferences;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chat);

        mainToolbar = (Toolbar) findViewById(R.id.main_chatbar);
        setSupportActionBar(mainToolbar);
        getSupportActionBar().setTitle("Chat Rooms");

        progressBar= (ProgressBar) findViewById(R.id.webViewProgressfaq);


        listView = (ListView) findViewById(R.id.listView);
        sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);


        arrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list_of_rooms);

        listView.setAdapter(arrayAdapter);


        if(isNetworkStatusAvialable (getApplicationContext())) {
            request_user_name();
            root.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    Set<String> set = new HashSet<String>();
                    Iterator i = dataSnapshot.getChildren().iterator();

                    while (i.hasNext()) {
                        set.add(((DataSnapshot) i.next()).getKey());
                    }

                    list_of_rooms.clear();
                    list_of_rooms.addAll(set);

                    arrayAdapter.notifyDataSetChanged();
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

        }else{
            Toast.makeText(getBaseContext(), "You're Offline!", Toast.LENGTH_SHORT).show();
            progressBar.setVisibility(View.VISIBLE);
        }



            listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

                    Intent intent = new Intent(getApplicationContext(),Chat_Room.class);
                    intent.putExtra("room_name",((TextView)view).getText().toString() );
                    intent.putExtra("user_name",name);
                    startActivity(intent);
                }
            });
        }





    private void request_user_name() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Enter name:");

        final EditText input_field = new EditText(this);
        builder.setCancelable(false);
        builder.setView(input_field);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {

                  name = input_field.getText().toString();
                SharedPreferences.Editor editor = sharedpreferences.edit();
                editor.putString("username", name);
                editor.commit();
            }
        });

        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                dialogInterface.cancel();
                request_user_name();
            }
        });

        builder.show();
    }

    public static boolean isNetworkStatusAvialable (Context context) {
        ConnectivityManager cm =
                (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        return activeNetwork != null &&
                activeNetwork.isConnectedOrConnecting();

    }
}

Answer 1

更改

editor.putString(username, e);
editor.commit();
builder.setView(input_field);
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {


                name = input_field.getText().toString();
        }
    });

要：

builder.setView(input_field);
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {

                name = input_field.getText().toString();

                editor.putString("username", name);
                editor.commit();
        }
    });

您尝试在用户输入任何内容之前保存用户名并按“确定”

修改

要在开头设置值：

创建EditText时设置用户名的值，否则如果username不存在，则会设置为空白字符串

final EditText input_field = new EditText(this); input_field.setText(sharedpreferences.getString("username",""));

强制光标位于EditText add：
的末尾
input_field.setSelection(input_field.getText().length());

Answer 2

如果您已保存数据，则不会在“确定”按钮单击上保存用户名并显示已保存的用户名设置文本。

用下面的替换你的功能，你会看到你的预期结果。

private void request_user_name() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Enter name:");

        final EditText input_field = new EditText(this);
        //String e  = input_field.getText().toString();
        final SharedPreferences.Editor editor = sharedpreferences.edit();       
        builder.setView(input_field);
        String savedName = sharedpreferences.getString(username,"");
        input_field.setText(savedName);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                  String name = input_field.getText().toString();
                  editor.putString(username, name);
                  editor.apply();
            }
        });

        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                dialogInterface.cancel();
                request_user_name();
            }
        });

        builder.show();
    }

使用Shared Prefrences在AlertDialog Builder中存储用户名字符串

2 个答案: