递归计数
package t20220518;
import java.util.HashMap;
import java.util.Map;
/**
* @Author: DengJia
* @Date: 2022/5/21 0:17
* @Description:
*/
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() {
StringBuilder result = new StringBuilder("{");
for (Map.Entry<Class<?>, Integer> pair : entrySet()) {
result.append(pair.getKey().getSimpleName());
result.append("=");
result.append(pair.getValue());
result.append(", ");
}
result.delete(result.length() - 2, result.length());
result.append("}");
return result.toString();
}
public static void main(String[] args) {
TypeCounter typeCounter = new TypeCounter(Object.class);
Integer i = 10;
Double j = 1.1;
Byte k = 7;
typeCounter.count(i);
typeCounter.count(j);
typeCounter.count(k);
System.out.println(typeCounter);
}
}
DJOSIMON