Sort and create new Objects before using TreeMap

[Lucian Botezatul]

have: List with 15 Objects (dummy)

public class Teilnehmer {
	
	String T_name;
	int richtigeAntworten;
	
	public void nichts (){
		
	}
		
}

The int value, random updated each ten steps (int)Math.round( Math.random() * 9 ).

Objects are sorted with TreeMap:

// Liste with dummy Objects
       
       SortedMap<Integer,String>Sortierte_liste2 = new TreeMap<Integer,String>(Collections.reverseOrder());
       
       Teilnehmer Ben1 = new Teilnehmer();
       Ben1.T_name = "Bernd \n";
       Ben1.richtigeAntworten = n1;
       Sortierte_liste2.put(Ben1.richtigeAntworten, Ben1.T_name);
       
    ...........
 
       Teilnehmer Ben10 = new Teilnehmer();
       Ben10.T_name = "Noemi \n";
       Ben10.richtigeAntworten = n10;
       Sortierte_liste2.put(Ben10.richtigeAntworten, Ben10.T_name);
       
       Teilnehmer Anwender = new Teilnehmer();
       Anwender.T_name = "--->  " + nam + "  <---" + "\n";
       Anwender.richtigeAntworten = antwortenAnwender;
       Sortierte_liste2.put(Anwender.richtigeAntworten, Anwender.T_name);
       
       
       ArrayList<String> namen;                  
       namen = new ArrayList<String>();
              
       JOptionPane myStatisticWindow = new JOptionPane();
       
       JTextArea MyList = new JTextArea("Richtig beantwortete Fragen   \n\n");   // inhalt in den Rahmen
       MyList.setEditable(false);                                        
       MyList.setOpaque(false);
       MyList.setFont(new Font("Arial", Font.PLAIN, 20));   
       
            for (Iterator it = Sortierte_liste2.entrySet().iterator(); it.hasNext(); ) 
           {                                                                             // inner loop
             Map.Entry entry = (Map.Entry) it.next();  
             MyList.append(entry.getKey().toString());  
             MyList.append(" " + "Fragen:   ");  
             MyList.append(entry.getValue().toString());  
             MyList.append("\n");  
             
          }  
            myStatisticWindow.showMessageDialog(null, MyList, "Teilnehmer Liste", JOptionPane.DEFAULT_OPTION);  // 
       
          
            
            result = namen.toArray();     
            return result;
            
        }

If i have some Objects like this: 20 Max, 18 Jane, 20 Mike, 22 John,

With my actual code i get the Result:

18 Jane
20 Mike
22 John

I would like something like this:

18 Jane
20 Max, Mike
22 John

My Idea: Put the Strings of the objects with the same int in one String together:

20 Max, 18 Jane, 20 Mike, 22 John, -> persort

20 Max compare 18 Jane -> no int mach
20 Max comparte 20 Mike-> match -> new Object 20 Max, Mike
....

result 20 Max, Mike; 18 Jane; 22 John -> run TreeMap over them and

18 Jane
20 Max, Mike
22 John

Any suggestions how i can make this pre sort, put the strings from the objects with the same (int) key on one new string of a new object?

[Luigi Plinge]

When you put a value into a map, it will return the previous value, or null if there was no previous entry. So do something like

String prev = map.put(key, newValue);
if(prev != null){
    map.put(key, prev + ", " + newValue)
}

[Lucian Botezatul]

THANK YOU LUIGI !!! it works, very nice idea !!

Final working version:

SortedMap<Integer,String>Sortierte_liste2 = new TreeMap<Integer,String>(Collections.reverseOrder());

Teilnehmer Ben1 = new Teilnehmer();
Ben1.T_name = "Bernd";
Ben1.richtigeAntworten = n1;
String prev = Sortierte_liste2.put(Ben1.richtigeAntworten, Ben1.T_name);
if(prev != null){
Sortierte_liste2.put(Ben1.richtigeAntworten, prev + ", " + Ben1.T_name);
}


...........

Teilnehmer Ben10 = new Teilnehmer();
Ben10.T_name = "Noemi";
Ben10.richtigeAntworten = n10;
String prev10 = Sortierte_liste2.put(Ben10.richtigeAntworten, Ben10.T_name);
if(prev10 != null){
Sortierte_liste2.put(Ben10.richtigeAntworten, prev10 + ", " + Ben10.T_name);
}

Teilnehmer Anwender = new Teilnehmer();
Anwender.T_name = "----> " + nam + " <----";
Anwender.richtigeAntworten = antwortenAnwender;
Sortierte_liste2.put(Anwender.richtigeAntworten, Anwender.T_name);


ArrayList<String> namen;
namen = new ArrayList<String>();

JOptionPane myStatisticWindow = new JOptionPane();

JTextArea MyList = new JTextArea("Richtig beantwortete Fragen \n\n"); // inhalt in den Rahmen
MyList.setEditable(false);
MyList.setOpaque(false);
MyList.setFont(new Font("Arial", Font.PLAIN, 20));

for (Iterator it = Sortierte_liste2.entrySet().iterator(); it.hasNext(); )
{ // inner loop
Map.Entry entry = (Map.Entry) it.next();
MyList.append(entry.getKey().toString());
MyList.append(" " + "Fragen: ");
MyList.append(entry.getValue().toString());
MyList.append("\n");

}
myStatisticWindow.showMessageDialog(null, MyList, "Teilnehmer Liste", JOptionPane.DEFAULT_OPTION); //



result = namen.toArray();
return result;

}