跨多个活动的SharedPreferences

Question

首先，我很抱歉，如果这是一个副本，我搜索，但没有找到答案。

我试图在多个活动中保持得分。用户从MainActivity开始，选择要回答的问题，然后重定向到该活动。用户将获得一个正确答案的积分，并返回给MainActivity以选择一个新的问题。

它是正确评分的问题，但它没有保存之间的问题得分。

主活性

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


    SharedPreferences settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);

    SharedPreferences.Editor editor = settings.edit();
    editor.putInt("score", userPoints);
    editor.commit();


};

Q1(每个问题的逻辑相同)。它运行时按一下按钮)

private SharedPreferences settings;
private int userPoints;
private int points;
 public void submitAnswer (View view) {

    if (correctAnswer.isChecked()) {
        userPoints = userPoints + 1;
    } else {
        userPoints = userPoints;
    }

    settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);
    points = settings.getInt("score", userPoints);

    Toast.makeText(this, "Answer saved", Toast.LENGTH_SHORT).show();
    Intent intent = new Intent(Q1.this, MainActivity.class);
    startActivity(intent);
}

我对这件事很陌生，我知道我错过了一些东西，我只是不知道它是什么。任何帮助都是非常感谢的。

编辑*

这是呼叫得分的按钮，它仍然只计算6分中的1个。

private int userPoints;
TextView pointsAwarded;
ImageButton home;
Button check;
int points;
SharedPreferences settings;    

check.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);
                points = settings.getInt("score", userPoints);

                pointsAwarded.setText(String.valueOf(points));
            }
        });

Answer 1

实际上，代码有一些错误。首先，您要将score保存在MainActivity中，而不是阅读它。您正在以score代替submitAnswer阅读或编辑它。

在处理SharedPreferences时，我通常是悲观的，所以我检查键是否已经用contains()设置了。

private int points;

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

    SharedPreferences settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);
    if(settings.contains("score"){
        points = settings.getInt("score", userPoints);
    }
    else{
        Log.e(TAG, "No score yet!");

        SharedPreferences.Editor editor = settings.edit();
        editor.putInt("score", 0);
        editor.commit();
    }
}

现在，在问题活动中，您可以从SharedPreferences读取当前点，并更新值并保存回SharedPreferences。

public void submitAnswer (View view) {
    if (correctAnswer.isChecked()) {
        SharedPreferences settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);
        if(settings.contains("score"){
            int points = settings.getInt("score", 0);
            points++;

            SharedPreferences.Editor editor = settings.edit();
            editor.putInt("score", points);
            editor.commit();
            Toast.makeText(this, "Answer saved : points = " + points, Toast.LENGTH_SHORT).show();
        }
        else{
            Log.e(TAG, "No score yet!");
        }
    } 
    else{
            Toast.makeText(this, "Wrong Answer", Toast.LENGTH_SHORT).show();
    }

    // There is no need to start the MainActivity through a new Intent just call finish();
    finish();
    //... and you return to the Activity that is at the top of the stack.

    //Intent intent = new Intent(Q1.this, MainActivity.class);
    //startActivity(intent);
}

Answer 2

```javascript

if (correctAnswer.isChecked()) {

userPoints = userPoints + 1;}

```     after this , u should save userPoints. maybe you forget.

Answer 3

您必须将当前用户点添加到保存点中，然后在添加后保存它：

private SharedPreferences settings;
private int userPoints;
private int points;
public void submitAnswer (View view) {

if (correctAnswer.isChecked()) {
    userPoints = userPoints + 1;
} else {
    userPoints = userPoints;
}

settings = getSharedPreferences("userScore", Context.MODE_PRIVATE);
points = settings.getInt("score", userPoints);

userPoints = userPoints + points ; // addition of current userpoints with saved points 

  // Now save this points 
  SharedPreferences.Editor editor = settings.edit();
  editor.putInt("score", userPoints );
  editor.commit();

Toast.makeText(this, "Answer saved", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(Q1.this, MainActivity.class);
startActivity(intent);
}