Java - 通过HashMap访问对象的数组列表(Key是对象)

Question

我试图循环遍历 HashMap，然后对于每个键，我想访问与该键关联的对象(发货)并访问我的数组列表以进行进一步分析。 HashMap中的每个对象/键都有相同的数组列表(metricList)。尽管我已经检查了私有(private)/公共(public)事物，但我似乎无法访问它。有人能指出我正确的方向吗？

我想我可能需要获取对象的类，然后使用方法“getList”...我尝试过但没有运气。

这是代码示例(删除了不相关的部分)，如果有帮助的话:

这是我的对象:

public class Shipment{

    //Members of shipment
    private final String shipment;
    public Date creationDate;
    public int creationTiming;
    public int processingTiming;
    public ArrayList<Integer> metricList;

    public void createArrayList() {
        // create list 
        metricList = new ArrayList<Integer>();
        // add metric to list
        metricList.add(creationTiming);
        metricList.add(processingTiming);
   }

    public ArrayList<Integer> getList() {
       return metricList;
   }
}

这是我创建 hashMap 并运行不同分析的类:

public class AnalysisMain {

    public static Map<String, Shipment> shipMap = new HashMap();

    public static void main(String[] args) {     
        try {
        ... // Different calls to analysis
        }
        catch {}  
    }
}

这就是问题发生的地方(它无法识别我已经有一个“metricList”，询问我是否要创建局部变量)

public class Metric_Analysis{
    public static void analyze() throws Exception{

        ResultSet rs;

            try {
                rs = getSQL("SELECT * FROM TEST_METRICS"); 
            }
            catch(Exception e) {
                //Pass the error
                throw new java.lang.Exception("DB Error: " + e.getMessage());
            }

            Iterator<Map.Entry<String, Shipment>> iterator = shipMap.entrySet().iterator();
            while(iterator.hasNext()){

                   Iterator<String> metricIterator = metricList.iterator();

                   //Above is the Array List I want to access and loop through
                   //I will then perform certain checked against other values on a table...

                    while (metricIterator.hasNext()) {
                    //I will perform certain things here
                    }
            }
    }
}

Answer 1

您需要从货件中取出 list 。您可以通过迭代器访问该对象: iterator.next();这还将把指针设置为列表/ map 中的下一个条目。

更改您的代码:

  Iterator<Map.Entry<String, Shipment>> iterator = shipMap.entrySet().iterator();
            while(iterator.hasNext()){

                   // Get the Entry from your Map and get the value from the Entry
                   Entry<String, Shipment> entry = iterator.next();
                   List<Integer> metricList = entry.getValue().getList();

                   Iterator<String> metricIterator = metricList.iterator();

                   //Above is the Array List I want to access and loop through
                   //I will then perform certain checked against other values on a table...

                    while (metricIterator.hasNext()) {
                    //I will perform certain things here
                    }
            }