Question

我正在尝试使用java在Android应用中保存和存储数据。目前，数据无法保存，导致我的应用程序崩溃。有人可以对我的代码提出任何建议吗？我的部分页面包含总预算，我很难存储并节省总预算。

         public class Summary extends Activity implements TextWatcher, View.OnClickListener
          {
         DecimalFormat df = new DecimalFormat("£0.00");
         int noOfGifts, giftsPurchased;
         double cost;
        EditText budgetEntered;
        double savedBudget = 0;
        String budgetString;

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

     budgetEntered = (EditText) findViewById(R.id.s2TotalBudget);
     budgetEntered.addTextChangedListener(this);

      Button saveBudget = (Button) findViewById(R.id.s2ViewList);
     saveBudget.setOnClickListener(saveButtonListener);
     if(savedBudget != 0)
      {
     saveBudget.setText(budgetString);
      }

    Bundle passedInfo = getIntent().getExtras();
     if (passedInfo != null)
     {
     cost = passedInfo.getDouble("cost");
     noOfGifts = passedInfo.getInt("noOfGifts");
     giftsPurchased = passedInfo.getInt("giftsPurchased");
     }

    Button logoutButton = (Button) findViewById(R.id.s2LogoutButton);
     logoutButton.setOnClickListener(new View.OnClickListener()
     {
     public void onClick(View view)
     {
        Intent myIntent = new Intent(Summary.this, MainActivity.class);
        startActivity(myIntent);
     }
     });

     Button viewList = (Button) findViewById(R.id.s2ViewList);
    viewList.setOnClickListener(new View.OnClickListener()
     {
     public void onClick(View view)
     {
        Intent myIntent = new Intent(Summary.this, GiftList.class);
        startActivity(myIntent);
     }
     });

     String [][] summary = {{"Number of Presents to buy:   ", (noOfGifts + "")},
          {"Number of Presents bought:", (giftsPurchased + "")},
          {"Cost:                      £", (cost + "")},
          {"Budget:                    £", "50"}};



     String passedBudget=null;

     //convert totalPresents to double from String
     String tempPresents = summary[0][1];
    int presents = Integer.parseInt(tempPresents);

  //convert presentsBought to double from String
  String tempBought = summary[1][1];
  int presentsToBuy = Integer.parseInt(tempBought);



    //Number of presents
    TextView s2PresentResult = (TextView) findViewById(R.id.s2PresentsResult);
    s2PresentResult.setText(summary[0][1]);

    //Number of presents to buy
    TextView s2PresentsBuyResult = (TextView) findViewById(R.id.s2PresntsBuyResult);
    s2PresentsBuyResult.setText((noOfGifts - giftsPurchased) + "");


     Bundle passedId = getIntent().getExtras();
     if (passedId != null)
     {
     passedBudget = passedId.getString("Enter Budget");
     }


    //EditText s2TotalBudget = (EditText) findViewById(R.id.s2TotalBudget);
    //s2TotalBudget .addTextChangedListener((android.text.TextWatcher) this);
    //s2TotalBudget .setText(passedBudget, TextView.BufferType.EDITABLE);


    //Number of people
    //TextView s2TotalBudget = (TextView) findViewById(R.id.s2TotalBudget);
    //s2TotalBudget.setText("Enter budget");




    //Number of people
    TextView s2TotalCost = (TextView) findViewById(R.id.s2TotalCost);
    s2TotalCost.setText(df.format(Double.parseDouble(summary[2][1])));

    //Output if over or under budget
    TextView s2CalculateOverBudget = (TextView) findViewById(R.id.s2CalculateOverBudget);

    //convert totalCost to double from String
    String temp = summary[2][1];
    double totalCost = Double.parseDouble(temp);

    //convert totalBudget to double from String
      String tempTwo = "14";
    double totalBudget = Double.parseDouble(tempTwo);


       if((totalCost>totalBudget)&&(totalBudget!=0))
      {
       s2CalculateOverBudget.setTextColor(Color.rgb(209,0,0));
       s2CalculateOverBudget.setText("You are over budget");
      }
       else if(totalBudget==0){
       s2CalculateOverBudget.setText("");
      }
      else {
       s2CalculateOverBudget.setText("You are within budget");
      }


      }

         public View.OnClickListener saveButtonListener = new View.OnClickListener()
         {
       @Override
       public void onClick(View v)
       {
       if(budgetEntered.getText().length()>0)
     {
          budgetString = budgetEntered.getText().toString();


     }
      }
    };



        public void onClick(View v)
     {

     }

    @Override
         public void beforeTextChanged(CharSequence s, int start, int count, int after)
        {

           }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count)
    {

     }

    @Override
   public void afterTextChanged(Editable s)
  {

Answer 1

这是在Android中存储和加载价值的最佳方式：

保存值:(将其放在要保存值的位置，例如在onStop或onPause方法中。或者，在您的情况下，在onClick方法中）

SharedPreferences settings = getSharedPreferences("MyPref", 0); SharedPreferences.Editor editor = settings.edit(); editor.putInt("testValue", value); editor.commit();
加载值：

SharedPreferences settings = getSharedPreferences("MyPref", 0); value = settings.getInt("testValue", defValue);

难以保存和存储

1 个答案: