java - 使用共享首选项存储数据

Question

在过去的 3 天里，我实际上每天花费 6-8 小时来搜索、阅读和执行有关共享首选项的各种示例，但没有任何成功。我走到了死胡同……非常令人沮丧!我的问题如下:

- 目标:我目前正在做一个非常基础的数学游戏，玩家将得到一个(随机)方程式，其中两个数字相互相乘。然后玩家将通过简单地按下三个选项按钮之一(一个包括正确答案)来给出答案。每个正确答案都会加分。

- 问题:现在，我想为游戏添加一个高分来存储最高分。我如何使用共享首选项或任何其他工作方法来存储我的数据。

"Score:"(@+id/textScore) 是我的包含分数 (TESTActivity.java) 的 TextView。 “Top Scores”(@+id/textTopScores) 是我的 TextView，我想在其中存储我的高分 (HighScoreActivity.java)。

- 应用的结构:

My app looks like this:
(a) MainActivity - main page with a start button leading the player to the Menu (= MenuActivity)
(b) MenuActivity - here the player have 3 buttons options which includes:
       Play Button --> leading to the TESTActivity
       High Score button -->> leading to the HighScoreActivity
       Help button -->> leading to the HelpActivity

.

activity_test.xml

 <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_test"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        tools:context="com.example.android.laboration2.TESTActivity">

        <TextView
            android:id="@+id/textOperator"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignTop="@+id/textPartA"
            android:layout_centerHorizontal="true"
            android:text="x"
            android:textSize="55sp" />

        <TextView
            android:text="="
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/textOperator"
            android:layout_alignLeft="@+id/textOperator"
            android:layout_alignStart="@+id/textOperator"
            android:layout_marginTop="70dp"
            android:id="@+id/textView"
            android:textSize="70sp" />

        <TextView
            android:id="@+id/textPartA"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignEnd="@+id/buttonChoice1"
            android:layout_alignParentTop="true"
            android:layout_alignRight="@+id/buttonChoice1"
            android:layout_marginTop="36dp"
            android:text="2"
            android:textSize="60sp" />

        <TextView
            android:id="@+id/textPartB"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="2"
            android:textSize="60sp"
            android:layout_alignTop="@+id/textOperator"
            android:layout_alignLeft="@+id/buttonChoice3"
            android:layout_alignStart="@+id/buttonChoice3" />

        <Button
            android:id="@+id/buttonChoice2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignTop="@+id/buttonChoice1"
            android:layout_centerHorizontal="true"
            android:text="4"
            android:textSize="30sp" />

        <Button
            android:id="@+id/buttonChoice3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@+id/buttonChoice2"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true"
            android:text="6"
            android:textSize="30sp" />

        <Button
            android:id="@+id/buttonChoice1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_below="@+id/textView"
            android:layout_marginTop="70dp"
            android:text="2"
            android:textSize="30sp" />

        <TextView
            android:id="@+id/textScore"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Score:"
            android:textSize="24sp"
            android:layout_alignParentBottom="true"
            android:layout_toLeftOf="@+id/buttonChoice2"
            android:layout_toStartOf="@+id/buttonChoice2"
            android:layout_marginRight="30dp"
            android:layout_marginEnd="30dp"
            android:layout_marginBottom="14dp" />

        <TextView
            android:id="@+id/textLevel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Level:"
            android:textSize="24sp"
            android:layout_alignBaseline="@+id/textScore"
            android:layout_alignBottom="@+id/textScore"
            android:layout_alignRight="@+id/textPartB"
            android:layout_alignEnd="@+id/textPartB" />

    </RelativeLayout>

TESTActivity.java

package com.example.android.laboration2;

import android.content.Context;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Random;


public class TESTActivity extends AppCompatActivity implements View.OnClickListener {


    Button buttonObjectChoice1;
    Button buttonObjectChoice2;
    Button buttonObjectChoice3;
    TextView textObjectPartA;
    TextView textObjectPartB;
    TextView textObjectScore;
    TextView textObjectLevel;
    TextView textObjectHighScoresScores;

    int correctAnswer;
    int currentScore = 0;
    int currentLevel = 1;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);


        textObjectPartA = (TextView) findViewById(R.id.textPartA);
        textObjectPartB = (TextView) findViewById(R.id.textPartB);
        textObjectHighScoresScores = (TextView) findViewById(R.id.textHighScoresScores);

        textObjectScore = (TextView) findViewById(R.id.textScore);
        textObjectLevel = (TextView) findViewById(R.id.textLevel);

        buttonObjectChoice1 = (Button) findViewById(R.id.buttonChoice1);
        buttonObjectChoice2 = (Button) findViewById(R.id.buttonChoice2);
        buttonObjectChoice3 = (Button) findViewById(R.id.buttonChoice3);

        buttonObjectChoice1.setOnClickListener(this);
        buttonObjectChoice2.setOnClickListener(this);
        buttonObjectChoice3.setOnClickListener(this);

        //Storing the score
        String highScore = textObjectHighScoresScores.getText().toString();
        int newHighScore = currentScore;

        SharedPreferences prefs = this.getSharedPreferences("StoringScore", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putInt(highScore, newHighScore);
        editor.apply();


        setQuestion();
    }//onCreate ends here



    @Override
    public void onClick(View view) {
        //Declaring a new int which will be used in all the cases
        int answerGiven = 0;
        switch (view.getId()) {

            //Initializes a new int with a value for buttonObjectChoice1,2,3
            case R.id.buttonChoice1:
                answerGiven = Integer.parseInt("" + buttonObjectChoice1.getText());
                break;

            case R.id.buttonChoice2:
                answerGiven = Integer.parseInt("" + buttonObjectChoice2.getText());
                break;

            case R.id.buttonChoice3:
                answerGiven = Integer.parseInt("" + buttonObjectChoice3.getText());
                break;
        }//switch ends here

        updateScoreAndLevel(answerGiven);
        setQuestion();
        
    }//onClick ends here



    void setQuestion() {
        //Generates the parts of the question
        int numberRange = currentLevel * 3;
        Random randInt = new Random();

        int partA = randInt.nextInt(numberRange);
        partA++;//To avoid a zero value

        int partB = randInt.nextInt(numberRange);
        partB++;//To avoid a zero value

        correctAnswer = partA * partB;
        int wrongAnswer1 = correctAnswer - 2;
        int wrongAnswer2 = correctAnswer + 2;

        textObjectPartA.setText("" + partA);
        textObjectPartB.setText("" + partB);

        //Gives a number between 0 and 2 for the multi choice buttons
        int buttonLayout = randInt.nextInt(3);
        switch (buttonLayout) {
            case 0:
                buttonObjectChoice1.setText("" + correctAnswer);
                buttonObjectChoice2.setText("" + wrongAnswer1);
                buttonObjectChoice3.setText("" + wrongAnswer2);
                break;

            case 1:
                buttonObjectChoice2.setText("" + correctAnswer);
                buttonObjectChoice3.setText("" + wrongAnswer1);
                buttonObjectChoice1.setText("" + wrongAnswer2);
                break;

            case 2:
                buttonObjectChoice3.setText("" + correctAnswer);
                buttonObjectChoice1.setText("" + wrongAnswer1);
                buttonObjectChoice2.setText("" + wrongAnswer2);
                break;
                
        }//switch ends here
    }//setQuestion ends here


    //Updates the Score & Level for the player
    void updateScoreAndLevel(int answerGiven){
        if(isCorrect(answerGiven)){
            for(int i = 1; i <= currentLevel; i++){
                currentScore = currentScore + i;
            }
            currentLevel++;
        }else{
            currentScore = 0;
            currentLevel = 1;
        }
        //Updates the Score & Level TextViews
        textObjectScore.setText("Score: " + currentScore);
        textObjectLevel.setText("Level: " + currentLevel);
    }//updateScoreAndLevel ends here


    //Sends a toast message to the player - if right = Correct!, if wrong = Wrong! :(.
    boolean isCorrect(int answerGiven){
        boolean correctTrueOrFalse;
        if(answerGiven == correctAnswer){
            Toast.makeText(getApplicationContext(), "Correct!", Toast.LENGTH_LONG).show();
            correctTrueOrFalse=true;
        }else{
            Toast.makeText(getApplicationContext(), "Wrong! :(", Toast.LENGTH_LONG).show();
            correctTrueOrFalse=false;
        }
        return correctTrueOrFalse;
    }//isCorrect ends here



}//TESTActivity ends here

activity_high_score.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_high_score"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.android.laboration2.HighScoreActivity">

    <TextView
        android:text="@string/high_scores"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="62dp"
        android:id="@+id/textHighScore"
        android:textSize="30sp"/>

    <TextView
        android:text="@string/top_scores"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textTopScores"
        android:textSize="16sp"
        android:layout_below="@+id/textHighScore"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="86dp" />

</RelativeLayout>

HighScoreActivity.java

package com.example.android.laboration2;

import android.content.Context;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class HighScoreActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_high_score);

        //getting preferences
        SharedPreferences prefs = this.getSharedPreferences("StoringScore", Context.MODE_PRIVATE);
        int newHighscore = prefs.getInt(highScore, null); //0 is the default value
        
    }//onCreate ends here


}//HighScoreActivity ends here

Answer 1

其实主要问题就在这里

 //Storing the score
    String highScore = textObjectHighScoresScores.getText().toString();
    int newHighScore = currentScore;

    SharedPreferences prefs = this.getSharedPreferences("StoringScore", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    editor.putInt(highScore, newHighScore);
    editor.apply();

editor.putInt(key,value) 您正在使用高分作为键，这将被更改，但共享偏好可以通过存储时使用的相同键获得。

你应该这样存储

SharedPreferences prefs = this.getSharedPreferences("StoringScore", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("myKey", score);
editor.apply();

获取分数->

SharedPreferences prefs = this.getSharedPreferences("StoringScore", Context.MODE_PRIVATE);
int newHighscore = prefs.getInt("myKey", 0);

Main point is KEY should be same