Pure Programmer
Blue Matrix

Cluster Map

Enumerations

L1

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Enums1.java
import java.util.HashMap;
import java.util.Map;
import org.pureprogrammer.Utils;

public class Enums1 {

	enum CompassPoint {
		NORTH,EAST,SOUTH,WEST
	}

	static String compassPointToString(final CompassPoint c) {
		String result = "";
		switch (c) {
			case NORTH:
				result = "North";
				break;
			case EAST:
				result = "East";
				break;
			case SOUTH:
				result = "South";
				break;
			case WEST:
				result = "West";
				break;
		}
		return result;
	}

	static CompassPoint turnRight(final CompassPoint c) {
		if (c == CompassPoint.NORTH) {
			return CompassPoint.EAST;
		} else if (c == CompassPoint.EAST) {
			return CompassPoint.SOUTH;
		} else if (c == CompassPoint.SOUTH) {
			return CompassPoint.WEST;
		} else {
			return CompassPoint.NORTH;
		}
	}

	public static void main(String[] args) {
		CompassPoint cp1 = CompassPoint.NORTH;
		System.out.println(Utils.join("", "cp1: ", cp1));
		System.out.println(Utils.join("", "SOUTH: ", compassPointToString(CompassPoint.SOUTH)));
		System.out.println(Utils.join("", "turnRight(cp1): ", compassPointToString(turnRight(cp1))));
		final CompassPoint CP2 = CompassPoint.EAST;
		if (cp1 == CP2) {
			System.out.println("cp1 == cp2");
		} else {
			System.out.println("cp1 != cp2");
		}
		cp1 = CP2;
		if (cp1 == CP2) {
			System.out.println("cp1 == cp2");
		} else {
			System.out.println("cp1 != cp2");
		}
	}
}
Output
$ javac -Xlint Enums1.java $ java -ea Enums1 cp1: NORTH SOUTH: South turnRight(cp1): East cp1 != cp2 cp1 == cp2
Enums2.java
import java.util.HashMap;
import java.util.Map;
import org.pureprogrammer.Utils;

public class Enums2 {

	enum Color {
		RED(1),
		GREEN(2),
		YELLOW(3),
		BLUE(4),
		MAGENTA(5),
		CYAN(6);

		private static Map<Integer, Color> byValue = new HashMap<>();
		static {
		    for (Color e: values()) {
		        byValue.put(e.value, e);
		    }
		}
		public final int value;
		private Color(int v) { value = v; }
		public int value() { return value; }
		public static Color valueOf(int i) {
		    Color result = byValue.get(i);
		    return result;
		}
	}

	static Color combineColors(final Color c1, final Color c2) {
		final int i1 = c1.value();
		final int i2 = c2.value();
		final int RESULT = i1 | i2;
		final Color RETURN_COLOR = Color.valueOf(RESULT);
		return RETURN_COLOR;
	}

	public static void main(String[] args) {
		Color c1 = Color.BLUE;
		System.out.println(Utils.join("", "c1: ", c1));
		System.out.println(Utils.join("", "RED: ", Color.RED));
		System.out.println(Utils.join("", "combineColors(c1, RED): ", combineColors(c1, Color.RED)));
		final Color c2 = Color.GREEN;
		System.out.println(Utils.join("", "combineColors(c1, c2): ", combineColors(c1, c2)));
		if (c1 == c2) {
			System.out.println("c1 == c2");
		} else {
			System.out.println("c1 != c2");
		}
		c1 = c2;
		if (c1 == c2) {
			System.out.println("c1 == c2");
		} else {
			System.out.println("c1 != c2");
		}
		final Color BAD = Color.valueOf(7);
		System.out.println(Utils.join("", "bad: ", BAD));
	}
}
Output
$ javac -Xlint Enums2.java $ java -ea Enums2 c1: BLUE RED: RED combineColors(c1, RED): MAGENTA combineColors(c1, c2): CYAN c1 != c2 c1 == c2 bad: null
java

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