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Semester 1/Programming 1/Java/examples/projects/chapter03/clock-display/NumberDisplay.java

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+
+/**
+ * The NumberDisplay class represents a digital number display that can hold
+ * values from zero to a given limit. The limit can be specified when creating
+ * the display. The values range from zero (inclusive) to limit-1. If used,
+ * for example, for the seconds on a digital clock, the limit would be 60, 
+ * resulting in display values from 0 to 59. When incremented, the display 
+ * automatically rolls over to zero when reaching the limit.
+ * 
+ * @author Michael Kölling and David J. Barnes
+ * @version 2016.02.29
+ */
+public class NumberDisplay
+{
+    private int limit;
+    private int value;
+
+    /**
+     * Constructor for objects of class NumberDisplay.
+     * Set the limit at which the display rolls over.
+     */
+    public NumberDisplay(int rollOverLimit)
+    {
+        limit = rollOverLimit;
+        value = 0;
+    }
+
+    /**
+     * Return the current value.
+     */
+    public int getValue()
+    {
+        return value;
+    }
+
+    /**
+     * Return the display value (that is, the current value as a two-digit
+     * String. If the value is less than ten, it will be padded with a leading
+     * zero).
+     */
+    public String getDisplayValue()
+    {
+        if(value < 10) {
+            return "0" + value;
+        }
+        else {
+            return "" + value;
+        }
+    }
+
+    /**
+     * Set the value of the display to the new specified value. If the new
+     * value is less than zero or over the limit, do nothing.
+     */
+    public void setValue(int replacementValue)
+    {
+        if((replacementValue >= 0) && (replacementValue < limit)) {
+            value = replacementValue;
+        }
+    }
+
+    /**
+     * Increment the display value by one, rolling over to zero if the
+     * limit is reached.
+     */
+    public void increment()
+    {
+        value = (value + 1) % limit;
+    }
+}