Question

我使用SharedPreferences来保存登录数据，就像记住我一样，

我设置了三个按钮，它有保存，清除，读取功能，

但在我保存一个登录数据后，我无法再更新保存信息，

顺便说一句，我已经设置了一个复选框来保存数据

但它看起来也不起作用..

有人可以帮我解决这个问题吗？

这是我的代码：

package com.example.escanui;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.MultiAutoCompleteTextView;

public class UserInfoActivity extends ActionBarActivity {

    public MultiAutoCompleteTextView userName;
    public MultiAutoCompleteTextView ipAddress;
    public Button loginConfirmBtw;
    public EditText passWord;
    public CheckBox memUserInfoCb;
    public Button save, read, clear;

    private SharedPreferences settings;
    private static final String data = "DATA";
    public static final String nameField ="NAME";
    public static final String passwordField = "PASSWORD";
    public static final String ipField = "IP";
    public static final String filePathFile ="FILEPATH";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_info);

        ipAddress = (MultiAutoCompleteTextView) findViewById(R.id.multiAutoCompleteTextView1);
        userName = (MultiAutoCompleteTextView) findViewById(R.id.multiAutoCompleteTextView2);
        passWord = (EditText) findViewById(R.id.editPassword1);
        loginConfirmBtw = (Button) findViewById(R.id.loginButton);
        memUserInfoCb = (CheckBox) findViewById(R.id.checkBox1);
        save = (Button) findViewById(R.id.saveBtw);
        read = (Button) findViewById(R.id.readBtw);
        clear = (Button) findViewById(R.id.clearBtw);

        setEventListener();


        if (memUserInfoCb.isChecked())
        {
            saveUserInfo();
            readData();
        }else{
            ipAddress.setText("");
            userName.setText("");
            passWord.setText("");
        }
    }

    public void readData()
    {
        settings = getSharedPreferences(data,0);
        userName.setText(settings.getString(nameField, ""));
        ipAddress.setText(settings.getString(ipField, ""));
        passWord.setText(settings.getString(passwordField, ""));
    }

    public void saveUserInfo()
    {
        settings = getSharedPreferences(data, 0);
        settings.edit().putString(ipField, ipAddress.getText().toString());
        settings.edit().putString(nameField, userName.getText().toString());
        settings.edit().putString(passwordField, passWord.getText().toString());
        settings.edit().commit();
    }

     public void setEventListener(){
            save.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    saveUserInfo();
                }
            });
            read.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    readData();
                }
            });
            clear.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    ipAddress.setText("");
                    userName.setText("");
                    passWord.setText("");
                }
            });
        }
}

Answer 1

您的问题是在保存数据时

每次调用settings.edit()时，您都会创建一个新的Editor对象。

当您致电editor.commit()或editor.apply()时，您会写下您对编辑器对象所做的所有更改。

因此，在您的代码中，每次调用Editor时都会创建4个settings.edit()个对象

    settings.edit().putString(ipField, ipAddress.getText().toString());
    settings.edit().putString(nameField, userName.getText().toString());
    settings.edit().putString(passwordField, passWord.getText().toString());
    settings.edit().commit();

只提交了最后一个settings.edit()，但您没有对该Editor个对象进行任何更改，因此，您什么也没有提交。

考虑一下

public void saveUserInfo()
{
    settings = getSharedPreferences(data, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = settings.edit();
    editor.putString(ipField, ipAddress.getText().toString());
    editor.putString(nameField, userName.getText().toString());
    editor.putString(passwordField, passWord.getText().toString());
    editor.commit();
}

Answer 2

如果要更新现有数据，则应使用edit().apply()而不是commit()，因为它会立即覆盖值。来自documentation：

与commit（）不同，后者将其首选项写入持久性同步存储，apply（）将其更改提交到内存中 SharedPreferences立即

使用SharedPreferences保存登录数据，但它只能保存一个

2 个答案: