42 lines
1.3 KiB
Java
42 lines
1.3 KiB
Java
// onjava/TypeCounter.java
|
|
// (c)2021 MindView LLC: see Copyright.txt
|
|
// We make no guarantees that this code is fit for any purpose.
|
|
// Visit http://OnJava8.com for more book information.
|
|
// Counts instances of a type family
|
|
package onjava;
|
|
import java.util.*;
|
|
import java.util.stream.*;
|
|
|
|
public class
|
|
TypeCounter extends HashMap<Class<?>, Integer> {
|
|
private Class<?> baseType;
|
|
public TypeCounter(Class<?> baseType) {
|
|
this.baseType = baseType;
|
|
}
|
|
public void count(Object obj) {
|
|
Class<?> type = obj.getClass();
|
|
if(!baseType.isAssignableFrom(type))
|
|
throw new RuntimeException(
|
|
obj + " incorrect type: " + type +
|
|
", should be type or subtype of " + baseType);
|
|
countClass(type);
|
|
}
|
|
private void countClass(Class<?> type) {
|
|
Integer quantity = get(type);
|
|
put(type, quantity == null ? 1 : quantity + 1);
|
|
Class<?> superClass = type.getSuperclass();
|
|
if(superClass != null &&
|
|
baseType.isAssignableFrom(superClass)) {
|
|
countClass(superClass);
|
|
}
|
|
}
|
|
@Override public String toString() {
|
|
String result = entrySet().stream()
|
|
.map(pair -> String.format("%s=%s",
|
|
pair.getKey().getSimpleName(),
|
|
pair.getValue()))
|
|
.collect(Collectors.joining(", "));
|
|
return "{" + result + "}";
|
|
}
|
|
}
|