Here is an example that creates a randomply sized int array with random numbers.

import java.awt.*;
import java.util.*;
import javax.swing.*;
import java.awt.event.*;

class ShowElement extends JFrame{
JButton ADD;
JPanel panel;
JLabel label1,label2;
final JTextField text1,text2;
ShowElement(){
label1 = new JLabel();
label1.setText("Enter Index:");
text1 = new JTextField(20);

label2 = new JLabel();
label2.setText("Element at specific Index:");
text2 = new JTextField(20);

ADD=new JButton("Show Element");

panel=new JPanel(new GridLayout(3,2));
panel.add(label1);
panel.add(text1);
panel.add(label2);
panel.add(text2);
panel.add(ADD);
add(panel,BorderLayout.CENTER);
Random r=new Random(); 
final int size=r.nextInt(50)+1;
final int arr[]=new int[size];
for(int i=0;i<arr.length;i++){
    int x=r.nextInt(100)+1;
    arr[i]=x;
    System.out.println(arr[i]);
}
ADD.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
    try{
    String value=text1.getText();
int in=Integer.parseInt(value);
if(in>=size){
    JOptionPane.showMessageDialog(null,"Out of Bounds");
}
else{
int ele=0;
for(int i=0;i<arr.length;i++){
    if(i==in){
        ele=arr[i];
    }
}

text2.setText(Integer.toString(ele));
}
    }
    catch(Exception e){}
    }
});
}

public static void main(String arg[])
{
try
{
ShowElement frame=new ShowElement();
frame.setSize(300,100);
frame.setVisible(true);
}
catch(Exception e){
}
}
}