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Java arrayList

Posted on 2013-11-22
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Last Modified: 2013-11-23
I want to be able to loop through my arraylist and determine which class it came from. I want to use that value for things further.

public class test extends JFrame{
            
    int [] people ;

    public test(){
          
	  Person [] people = new Person[4];
	  float grades[] = {90,90,91,92,92,93,93,94,94,95,96,96,95,95,95};
          
          ArrayList<Person> list = new ArrayList<Person>(4);
	  list.add(new Teacher("Teacher ", "One", 420));
	  list.add(new Student("Student ", "One", 11111, grades));
          list.add(new Teacher("Teacher ", "Two", 421));
	  list.add(new Student("Student ", "Two", 22222, grades));
          
          setLayout(new GridLayout(4, 2, 5, 5));
          
          for (int i=0; i< list.size(); ++i){
              
              add(new JTextField("" + list.get(i)), BorderLayout.WEST);
          }
           

    
    }
    
      public static void main(String[] args){
                  
      test frame = new test(); 
      frame.setTitle("Listing");
      frame.setSize(400, 400);
      frame.setLocationRelativeTo(null); 
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //allow x to exit
      frame.setVisible(true);
       
}
}

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Question by:lostinspace9
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Expert Comment

by:krakatoa
ID: 39669532
Just use the instanceof operator -  if(it.next() instanceof Student){do smthg;}
 
Of course you won't be able to do that for the Person class, as they are all people.

(Iterator "it" = list.iterator())
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Accepted Solution

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CEHJ earned 500 total points
ID: 39669616
Why put teachers and students in the same list in the first place?
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Expert Comment

by:krakatoa
ID: 39669654
Why put teachers and students in the same list in the first place?

 . . . which is a rather excellent point.
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Author Closing Comment

by:lostinspace9
ID: 39670748
Thanks again for the rather simple tip.......Just been staring at this thing too long..
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Expert Comment

by:krakatoa
ID: 39671014
Hmm. Right answer to the wrong question.
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Expert Comment

by:CEHJ
ID: 39671337
:)
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Expert Comment

by:krakatoa
ID: 39671339
:(
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