45 lines
1.4 KiB
Java
45 lines
1.4 KiB
Java
// onjava/TypeCounter.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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// Counts instances of a type family.
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package onjava;
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import java.util.*;
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public class
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TypeCounter extends HashMap<Class<?>, Integer> {
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private Class<?> baseType;
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public TypeCounter(Class<?> baseType) {
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this.baseType = baseType;
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}
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public void count(Object obj) {
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Class<?> type = obj.getClass();
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if(!baseType.isAssignableFrom(type))
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throw new RuntimeException(
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obj + " incorrect type: " + type +
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", should be type or subtype of " + baseType);
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countClass(type);
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}
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private void countClass(Class<?> type) {
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Integer quantity = get(type);
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put(type, quantity == null ? 1 : quantity + 1);
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Class<?> superClass = type.getSuperclass();
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if(superClass != null &&
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baseType.isAssignableFrom(superClass))
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countClass(superClass);
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}
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@Override
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public String toString() {
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StringBuilder result = new StringBuilder("{");
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for(Map.Entry<Class<?>, Integer> pair : entrySet()) {
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result.append(pair.getKey().getSimpleName());
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result.append("=");
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result.append(pair.getValue());
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result.append(", ");
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}
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result.delete(result.length() - 2, result.length());
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result.append("}");
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return result.toString();
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}
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}
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