org.apache.juneau.internal.HashCode Maven / Gradle / Ivy
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package org.apache.juneau.internal;
/**
* Utility class for generating integer hash codes.
*
*
* General usage:
*
* int hashCode = new HashCode().add("foobar").add(myobject).add(123).get();
*
*/
public class HashCode {
private int hashCode = 1;
/**
* Create a new HashCode object.
*
* @return A new HashCode object.
*/
public static final HashCode create() {
return new HashCode();
}
/**
* Hashes the hashcode of the specified object into this object.
*
* @param o The object whose hashcode will be hashed with this object.
* @return This object (for method chaining).
*/
public HashCode add(Object o) {
o = unswap(o);
add(o == null ? 1 : o.hashCode());
return this;
}
/**
* Hashes the hashcode into this object.
*
*
* The formula is simply hashCode = 31*hashCode + i;
*
* @param i The hashcode to hash into this object's hashcode.
* @return This object (for method chaining).
*/
public HashCode add(int i) {
hashCode = 31*hashCode + i;
return this;
}
/**
* Return the calculated hashcode value.
*
* @return The calculated hashcode.
*/
public int get() {
return hashCode;
}
/**
* Converts the object to a normalized form before grabbing it's hashcode.
*
*
* Subclasses can override this method to provide specialized handling (e.g. converting numbers to strings so that
* 123 and "123" end up creating the same hashcode.)
*
*
* Default implementation does nothing.
*
* @param o The object to normalize before getting it's hashcode.
* @return The normalized object.
*/
protected Object unswap(Object o) {
return o;
}
}