如何从一个物体拉一个ArrayList的具体数据 [英] How to pull specific data from an object in an arraylist

问题描述

好吧，不知道标题的措辞是正确，但说我有每个数据的两个字符串（比方说，一个Statename的和的cityName）存储到一个ArrayList三个对象。是有可能的状态名作为字符串变量（称之为searchStateName），则必须通过在列表中的对象的方法，搜索输入和比较searchStateName到Statename的ArrayList中的每个对象物的内部，并且当发现匹配有它返回的cityName是相同的对象匹配Statename的？

Ok, not sure if the title worded that correctly but say I have three objects with two strings of data each(Lets say a stateName and a cityName) stored into an arraylist. Is it possible to enter in a state name in as a string variable(call it searchStateName), then have a method search through the objects in the list and compare searchStateName to the stateName inside each object in the arraylist, and when a match is found have it return the cityName that is inside the same object as the matching stateName?

我试图做同样的事情目前并想找出自己，但我一直在做这个了几个小时和我完全丧失。任何人都可以点我在正确的方向？

I am trying to do something similar currently and would like to figure it out myself, but I have been working on this for the past hour and am completely lost. Could anyone point me in the right direction?

推荐答案

这是这种方法。假设你有一个叫做类 SC ，你必须在为他们两个实例变量和getter和setter。您需要初始化内部主其中3个对象：

This is the approach. Say you have a class called SC and you have two instance variables in it and getters and setters for them. You need to initialize 3 objects of them inside your main:

SC a = new SC("Illinois ","Chicago ");
SC b = new SC("Michigan ","Detroit");
SC c = new SC("New York"," New York");

然后创建一个的ArrayList 对象的 SC 并添加 SC的那些3个对象到的ArrayList

And then create an ArrayList of object SC and add those 3 objects of SC to that ArrayList.

ArrayList<SC> list = new ArrayList<SC>();
list.add(a);
list.add(b);
list.add(c);

现在调用搜索状态名称，并返回该城市名称的方法，如果找到它：

Now call the method that search for a state name and returns the city name if it finds it:

this.searchStateName("Illinois");

实际的此方法的实现与的for-each 循环：

public String searchStateName(String stateName){
 String result = "No city found.";
      for (SC sc : list )
         if (sc.getStateName().equalsIgnoreCase(stateName)){
          result = sc.getCityName();
          break;
        }
    }
 return result;
}

如果你不舒服的for-each 循环，那么你可以使用常规的为下面循环。我注释掉的目的。但它会正常工作，给你正确的城市名称。

If you are not comfortable with for-each loop then you can use the regular for loop below. I commented out on purpose. But it will work correctly and give you the correct city name.

//public String searchStateName(String stateName){
// String result = null;
//      for (int i = 0; i < list.size(); i++){
//         if (list.get(i).getStateName() .equalsIgnoreCase(stateName)){
//          result = list.get(i).getCityName();
//          break;
//        }
//    }
// return result;
//}

和多数民众赞成它。让我知道如果你需要进一步的帮助。

And thats it. Let me know if you need help further.

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