我如何从onactivityresult总结价值 [英] How do I sum up value from onactivityresult

问题描述

我在活动A中有一个列表视图。我想总结从活动B返回到活动A的总金额，但我不知道如何添加它们。

  @覆盖 
  public   void  onActivityResult（ int  requestCode， int  resultCode ，Intent数据）{ //  从活动B接收并填充ListView A  
  if （resultCode == RESULT_OK）{
  if （requestCode == PROJECT_REQUEST_CODE）{
 ReceiveAmount = data.getStringExtra（  amount）; 
 Toast.makeText（getApplication（）， 总金额为 + ReceiveAmount，LENGTH_SHORT） 。节目（）; 
} 
} 
} 
} 

假设活动BI返回金额5 ，然后我再次去活动B并返回值10.我希望吐司显示值15而不是总是5.





< b>已编辑

  public   void  onActivityResult（ int  requestCode， int  resultCode，Intent data） { //  从活动B接收并填充ListView A  
  if （resultCode == RESULT_OK）{
  if （requestCode == PROJECT_REQUEST_CODE）{
  double  sum =  0 ; 
 ReceiveAmount = data.getStringExtra（  amount）; 
 sum = + ReceiveAmount; 
 Toast.makeText（getApplication（）， 总金额为 + sum，LENGTH_SHORT） 。节目（）; 
} 
} 
} 
} 

我尝试了什么：



谷歌但未找到答案。谢谢

解决方案

在活动A中创建一个变量说sum，初始值为零，每当从活动B返回时，将返回的金额添加到此总和 并将其展示在吐司中。这就是全部。



+++++ [第2轮] +++++

 < span class =code-keyword> public   class  MainActivity  extends 活动{
 
  double  sum =  0 ; 
 
  protected   void  onCreate（Bundle savedInstanceState）{
  //   ...  

了解详情了解类成员（Java™教程>学习Java语言>类和对象） [ ^ ]



+++++ [第3轮] +++++

我注意到了这个

 sum = + ReceiveAmount; 

你确定你的代码实际运行了吗？

检查出来： Java中的操作员 [ ^

I have a listview in Activity A. I want to sum up the total amount which are return from Activity B to Activity A, but I have no idea on how to add them up.

@Override
  public void onActivityResult(int requestCode, int resultCode, Intent data) { // receive from Activity B and populate ListView A
      if (resultCode == RESULT_OK) {
          if (requestCode == PROJECT_REQUEST_CODE) {
              ReceiveAmount = data.getStringExtra("amount");
             Toast.makeText(getApplication(),"Total Amount is"+ReceiveAmount,LENGTH_SHORT).show();
              }
          }
      }
  }

Assume in Activity B I return amount 5, then I go to Activity B again and return value 10. I want the toast display value 15 instead of always 5.


Edited

public void onActivityResult(int requestCode, int resultCode, Intent data) { // receive from Activity B and populate ListView A
     if (resultCode == RESULT_OK) {
         if (requestCode == PROJECT_REQUEST_CODE) {
             double sum = 0;
             ReceiveAmount = data.getStringExtra("amount");
            sum = + ReceiveAmount;
            Toast.makeText(getApplication(),"Total Amount is"+sum,LENGTH_SHORT).show();
             }
         }
     }
 }

What I have tried:

Google but no answer found. Thanks

解决方案

Create a variable say "sum" in activity A with an initial value of zero, whenever it returns from activity B, add the returned amount to this "sum" and display it in toast. That's all.

+++++[round 2]+++++

public class MainActivity extends Activity {

    double sum = 0;

    protected void onCreate(Bundle savedInstanceState){
//...

Learn more Understanding Class Members (The Java™ Tutorials > Learning the Java Language > Classes and Objects)[^]

+++++[round 3]+++++
I noticed this

sum = + ReceiveAmount;

are you sure your code actually run?
check this out: Operators in Java[^]

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