//: c09:Map1.java // From 'Thinking in Java, 2nd ed.' by Bruce Eckel // www.BruceEckel.com. See copyright notice in CopyRight.txt. // Things you can do with Maps. import java.util.*; import com.bruceeckel.util.*; public class Map1 { static Collections2.StringPairGenerator geo = Collections2.geography; static Collections2.RandStringPairGenerator rsp = Collections2.rsp; // Producing a Set of the keys: public static void printKeys(Map m) { System.out.print("Size = " + m.size() +", "); System.out.print("Keys: "); System.out.println(m.keySet()); } // Producing a Collection of the values: public static void printValues(Map m) { System.out.print("Values: "); System.out.println(m.values()); } public static void test(Map m) { Collections2.fill(m, geo, 25); // Map has 'Set' behavior for keys: Collections2.fill(m, geo.reset(), 25); printKeys(m); printValues(m); System.out.println(m); String key = CountryCapitals.pairs[4][0]; String value = CountryCapitals.pairs[4][1]; System.out.println("m.containsKey(\"" + key + "\"): " + m.containsKey(key)); System.out.println("m.get(\"" + key + "\"): " + m.get(key)); System.out.println("m.containsValue(\"" + value + "\"): " + m.containsValue(value)); Map m2 = new TreeMap(); Collections2.fill(m2, rsp, 25); m.putAll(m2); printKeys(m); key = m.keySet().iterator().next().toString(); System.out.println("First key in map: "+key); m.remove(key); printKeys(m); m.clear(); System.out.println("m.isEmpty(): " + m.isEmpty()); Collections2.fill(m, geo.reset(), 25); // Operations on the Set change the Map: m.keySet().removeAll(m.keySet()); System.out.println("m.isEmpty(): " + m.isEmpty()); } public static void main(String[] args) { System.out.println("Testing HashMap"); test(new HashMap()); System.out.println("Testing TreeMap"); test(new TreeMap()); } } ///:~