java - 未使用 SharedPreferences 存储的字符串

Question

我试图在 SharedPreferences 中保存两个字符串。当我第一次运行该应用程序时，它们会按预期显示。当我关闭应用程序并重新打开应用程序时，字符串不再设置为关闭应用程序之前的值，而是使用默认字符串值。为什么是这样？下面是我保存和检索这两个字符串的方法。

这是两个字符串

Intent intent = getIntent();

    playerName1 = intent.getStringExtra("PLAYER_ONE");
    playerName2 = intent.getStringExtra("PLAYER_TWO");

这是存储字符串的方法

private void savePlayerNames()
{
    SharedPreferences sharedPreferences = getSharedPreferences("playerNames", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString("playerOne", playerName1);
    editor.putString("playerTwo", playerName2);
    editor.commit();
}

这里是他们被取回的地方

private void displayPlayerNames(int current)
{
    SharedPreferences sharedPreferences = getSharedPreferences("playerNames", Context.MODE_PRIVATE);

    String playerOne = sharedPreferences.getString("playerOne","Player 1");
    String playerTwo = sharedPreferences.getString("playerTwo","Player 2");

    if(playerchoice[current].getText().toString().equals(""))
    {
        if (savedTracker % 2 == 0)
        {
            playerchoice[current].setText(x);
            playerNameDisplay.setText(playerTwo + "'s Go!");
            savedTracker++;
        }
     }
 }

Answer 1

使用下面的类。这将帮助您摆脱所有令人困惑的代码

public class PlayersData {

private SharedPreferences sharedPreferences;
private SharedPreferences.Editor editor;
private static final String PLAYERS_DATA = "PLAYERS_DATA";
private static final String PLAYERS = "PLAYERS";

public PlayersData(Context context) {
    sharedPreferences = context.getSharedPreferences(PLAYERS_DATA, Context.MODE_PRIVATE);
    editor = sharedPreferences.edit();
}

public void savePlayers(Players players) {
    Gson gson = new Gson();
    String json = gson.toJson(players);
    editor.putString(PLAYERS, json);
    editor.commit();
}

public Players getPlayers() {
    Gson gson = new Gson();
    String json = sharedPreferences.getString(PLAYERS, null);
    return gson.fromJson(json, Players.class);
}

public class Players{

    private String one;
    private String two;

    public Players() {

    }

    public Players(String one, String two) {
        this.one = one;
        this.two = two;
    }

    public String getOne() {
        return one;
    }

    public void setOne(String one) {
        this.one = one;
    }

    public String getTwo() {
        return two;
    }

    public void setTwo(String two) {
        this.two = two;
    }
}

}

要获取/保存数据，只需初始化类并执行操作:

PlayersData playersData = new PlayersData(this); //this is the context

有一件事我忘了提，我使用了 gson lib，所以将这一行添加到您的应用级 Gradle 文件并构建您的 Gradle:

implementation 'com.google.code.gson:gson:2.8.5'