Java

Question

我正在尝试遍历 HashMap，然后对于每个键，我想访问与该键关联的对象 (Shipment)，并访问我的数组列表以进行进一步分析。 HashMap中的每个object/key都有相同的数组列表（metricList）。我似乎无法访问它，尽管我已经检查了 private/public 东西。有人能指出我正确的方向吗？

我想我可能需要获取我的对象的 class 然后使用方法 "getList"...我尝试过但没有成功。

这是代码示例（删除了不相关的部分）如果有帮助：

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class我通过不同的分析创建hashMap和运行的地方：

public class AnalysisMain {

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

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

这是问题所在（它不识别我已经有一个"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

您需要从您的货件中取出清单。您可以通过以下方式从迭代器访问对象：iterator.next(); 这还将在您的 List/Map.

中设置指向下一个条目的指针

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
                    }
            }

Java - 通过HashMap访问对象的数组列表（Key为object）

Java - Access Object's Array List through HashMap (Key is object)

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