715: Mainline

The following definition both extends JComponent and implements MeterInterface.

Note that the setters required by the MeterInterface include calls to the zero-argument repaint method. You learned in Segment 712 that Java calls paint whenever you call repaint. Thus, calls to the meter setters cause the meter to be redrawn.

import java.awt.*; 
import javax.swing.*; 
public class Meter extends JComponent implements MeterInterface { 
 String title = "Title to be Supplied"; 
 int minValue, maxValue, value; 
 // Constructor: 
 public Meter (int x, int y) { 
  minValue = x;  
  maxValue = y; 
  value = (y + x) / 2; 
 } 
 // Setters: 
 public void setValue(int v) {value = v; repaint();} 
 public void setTitle(String t) {title = t; repaint();} 
 // Getter to be defined 
 // Paint to be defined 
}