Question

I have this problem:

1) There are objects placed in the TreeMap through the JTextField. (Phonebook-like program).

2)There are buttons that implement view of available records in TreeMap.
When you click on these buttons next / previous available objects of TreeMap displaying in JTextField. (scroll through the available records).

I tried this code, but it didn’t work :/

btn[4].addActionListener(new ActionListener(){
     Iterator iter = tree.keySet().iterator();
      public void actionPerformed(ActionEvent e) {
         if (iter.hasNext()){
         String str = iter.next().toString();
         fldFio.setText(str);
         fldNumber.setText(tree.get(str));
         }
      }
}); 

I added this line in method actionPerformed as a first line:

System.out.println(iter1.hasNext());

Result is “false”, if it will be anyhow helpful.

Answer 1

I released this thing using methods from NavigableMap. Thx all for help:

btn[4].addActionListener(new ActionListener(){
       String str;
       public void actionPerformed(ActionEvent e) {
           if (tree.size() != 0){
               if ((str)==null){
                   str = tree.firstKey();
                   } else {
                   fldFio.setText(str);
                   fldNumber.setText(tree.get(str));
                   str = tree.higherKey(str);   
                   }
          }
       }
   });