How to retrieve values stored in Tree map collections?

Question

And how to compare values with that of the values retrieved from database to conclude into just 1 result?

I am new to programming, please be kind.

below is my complete function:-

public String startpgm(String x){

    String p    = null;
    double West     = 2;
    double North    = 3;
    double South    = 4;    
    double East     = 4;

    String w    =null;
    String n    =null;
    String s    =null;
    String e    =null;

    TreeMap<Double, Collection<String>> names = new TreeMap<Double, Collection<String>>();
    put(names, West, "west");
    put(names, North, "north");
    put(names, South, "south");
    put(names, East, "east");


    Collection<String> maximumPriorityValues = names.lastEntry().getValue();
    for(String value : maximumPriorityValues){
        System.out.println("Priority:"+value);    
        p=value;



        while(value.equals(maximumPriorityValues)){

            w= value.substring("west");
            n= value.substring("north");
            s= value.substring("south");
            e= value.substring("east");     
            }
    }

    System.out.println("Current Priority:"+w+","+n+","+s+","+e);


    String qrypriority = "select priority from tbl_priority order by updated_at ASC LIMIT 1";

    Statement stmt = (Statement) conn.createStatement();

    ResultSet PastPriority=stmt.executeQuery(qrypriority);
    if (PastPriority.equals(w)){

        String qryupdate = "update tbl_priority set active=1 where priority='west'";
        int b=stmt.executeUpdate(qryupdate);

    }
    if (PastPriority.equals(n)){

        String qryupdate = "update tbl_priority set active=1 where priority='north'";
        int b=stmt.executeUpdate(qryupdate);

    }
    if (PastPriority.equals(s)){

        String qryupdate = "update tbl_priority set active=1 where priority='south'";
        int b=stmt.executeUpdate(qryupdate);

    }
    if (PastPriority.equals(e)){

        String qryupdate = "update tbl_priority set active=1 where priority='east'";
        int b=stmt.executeUpdate(qryupdate);

    }

    String qrystatus = "select priority from tbl_priority order by updated_at ASC LIMIT 1";


    ResultSet status=stmt.executeQuery(qrystatus);

    if (!PastPriority.next()){
        String qrypriority2 = "select priority from tbl_priority order by updated_at ASC LIMIT 2";


        ResultSet PastPriority2=stmt.executeQuery(qrypriority);
        if (PastPriority.equals(w)){

            String qryupdate = "update tbl_priority set active=1 where priority='west'";
            int b=stmt.executeUpdate(qryupdate);

        }
        if (PastPriority.equals(n)){

            String qryupdate = "update tbl_priority set active=1 where priority='north'";
            int b=stmt.executeUpdate(qryupdate);

        }
        if (PastPriority.equals(s)){

            String qryupdate = "update tbl_priority set active=1 where priority='south'";
            int b=stmt.executeUpdate(qryupdate);

        }
        if (PastPriority.equals(e)){

            String qryupdate = "update tbl_priority set active=1 where priority='east'";
            int b=stmt.executeUpdate(qryupdate);

        }


    }



    return p;
}

I am beginner to programming, please do not disappoint me!! My problem is, i cannot obtain the data stored in "value" rather than just printing it. i want to store each data obtained in to variable for further process

What i am trying to do with this program is:-

1. To find the highest priority values among north, east, west and south. (to determine highest priority, if multiple values are returned below methods is applied)
2. find the existing priority of the sames sides in the db, in which priority is high for the last updated side.
3. If the obtained priority doesn't match with last updated side, then last updated two sides are considered.

My objective in a nutshell:- to identify the highest priority side & when multiple values are returned compare the existing priority and conclude at which side have to be provided with priority, i.e updating 'tbl_priroty' with 'active=1' for the respective side.

Thanks in advance.

Answer 1

Here is what I would do.

NavigableMap<Double, List<String>> priorityMap = new TreeMap<Double, List<String>>();
// create a map that contains priorities and names

Afterwards fill the map. To do so I would recommend using a different data structure for reading, e.g.,

double[] priorities = new double[] {2, 3, 4, 4};
String[] names = new String[] {"west", "north", "south", "east"};

Because if you use priorityMap.put(4, "String1"); followed by priorityMap.put(4, "String2"); you overwrite the first put.

So:

for (int i = 0; i < priorities.length; i++) {
     // if the priority, i.e., the String is no key so far
     if (!priorityMap.contains(priorities[i])
        // we create a new List that saves the names containing 
        // those which belong to the priority.
        priorityMap.put(priorities[i], new ArrayList<String>());
     // afterwards we add the name to the priority list
     priorityMap.get(priorities[i]).add(names[i]);
}

Now you have the map that contains all your priorities and their respective names.

List<String> highestPriorityNames = priorityMap.lastEntry();
for (String name : highestPriorityNames) {
      // do whatever you want with the high priority name
}

Additionally, this loop makes no sense

while(value.equals(maximumPriorityValues)){
    w= value.substring("west");
    n= value.substring("north");
    s= value.substring("south");
    e= value.substring("east");     
}

You cannot compare a String with a Collection or List. As it will never be true. You do not have to check whether highestPriorityNames.contains(name), because you loop through all names that are within this list.