66 lines
2.3 KiB
Java
66 lines
2.3 KiB
Java
// containersindepth/Maps.java
|
|
// Things you can do with Maps.
|
|
import java.util.concurrent.*;
|
|
import java.util.*;
|
|
import com.mindviewinc.util.*;
|
|
|
|
public class Maps {
|
|
public static void printKeys(Map<Integer,String> map) {
|
|
System.out.print("Size = " + map.size() + ", ");
|
|
System.out.print("Keys: ");
|
|
System.out.println(map.keySet()); // Produce a Set of the keys
|
|
}
|
|
public static void test(Map<Integer,String> map) {
|
|
System.out.println(map.getClass().getSimpleName());
|
|
map.putAll(new CountingMapData(25));
|
|
// Map has 'Set' behavior for keys:
|
|
map.putAll(new CountingMapData(25));
|
|
printKeys(map);
|
|
// Producing a Collection of the values:
|
|
System.out.print("Values: ");
|
|
System.out.println(map.values());
|
|
System.out.println(map);
|
|
System.out.println("map.containsKey(11): " + map.containsKey(11));
|
|
System.out.println("map.get(11): " + map.get(11));
|
|
System.out.println("map.containsValue(\"F0\"): "
|
|
+ map.containsValue("F0"));
|
|
Integer key = map.keySet().iterator().next();
|
|
System.out.println("First key in map: " + key);
|
|
map.remove(key);
|
|
printKeys(map);
|
|
map.clear();
|
|
System.out.println("map.isEmpty(): " + map.isEmpty());
|
|
map.putAll(new CountingMapData(25));
|
|
// Operations on the Set change the Map:
|
|
map.keySet().removeAll(map.keySet());
|
|
System.out.println("map.isEmpty(): " + map.isEmpty());
|
|
}
|
|
public static void main(String[] args) {
|
|
test(new HashMap<>());
|
|
test(new TreeMap<>());
|
|
test(new LinkedHashMap<>());
|
|
test(new IdentityHashMap<>());
|
|
test(new ConcurrentHashMap<>());
|
|
test(new WeakHashMap<>());
|
|
}
|
|
}
|
|
/* Output: (First 11 Lines)
|
|
HashMap
|
|
Size = 25, Keys: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
|
|
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
|
|
Values: [A0, B0, C0, D0, E0, F0, G0, H0, I0, J0, K0, L0,
|
|
M0, N0, O0, P0, Q0, R0, S0, T0, U0, V0, W0, X0, Y0]
|
|
{0=A0, 1=B0, 2=C0, 3=D0, 4=E0, 5=F0, 6=G0, 7=H0, 8=I0,
|
|
9=J0, 10=K0, 11=L0, 12=M0, 13=N0, 14=O0, 15=P0, 16=Q0,
|
|
17=R0, 18=S0, 19=T0, 20=U0, 21=V0, 22=W0, 23=X0, 24=Y0}
|
|
map.containsKey(11): true
|
|
map.get(11): L0
|
|
map.containsValue("F0"): true
|
|
First key in map: 0
|
|
Size = 24, Keys: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
|
|
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
|
|
map.isEmpty(): true
|
|
map.isEmpty(): true
|
|
...
|
|
*/
|