panda.lang.builder.EqualsBuilder Maven / Gradle / Ivy
package panda.lang.builder;
/**
* Assists in implementing {@link Object#equals(Object)} methods.
*
* This class provides methods to build a good equals method for any
* class. It follows rules laid out in
* Effective Java
* , by Joshua Bloch. In particular the rule for comparing doubles,
* floats, and arrays can be tricky. Also, making sure that
* equals() and hashCode() are consistent can be
* difficult.
*
* Two Objects that compare as equals must generate the same hash code,
* but two Objects with the same hash code do not have to be equal.
*
* All relevant fields should be included in the calculation of equals.
* Derived fields may be ignored. In particular, any field used in
* generating a hash code must be used in the equals method, and vice
* versa.
*
* Typical use for the code is as follows:
*
* public boolean equals(Object obj) {
* if (obj == null) { return false; }
* if (obj == this) { return true; }
* if (obj.getClass() != getClass()) {
* return false;
* }
* MyClass rhs = (MyClass) obj;
* return new EqualsBuilder()
* .appendSuper(super.equals(obj))
* .append(field1, rhs.field1)
* .append(field2, rhs.field2)
* .append(field3, rhs.field3)
* .isEquals();
* }
*
*
*/
public class EqualsBuilder implements Builder {
/**
* If the fields tested are equals. The default value is true.
*/
private boolean isEquals = true;
/**
*
* Constructor for EqualsBuilder.
*
*
* Starts off assuming that equals is true.
*
*
* @see Object#equals(Object)
*/
public EqualsBuilder() {
// do nothing for now.
}
// -------------------------------------------------------------------------
/**
*
* Adds the result of super.equals() to this builder.
*
*
* @param superEquals the result of calling super.equals()
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder appendSuper(boolean superEquals) {
if (isEquals == false) {
return this;
}
isEquals = superEquals;
return this;
}
// -------------------------------------------------------------------------
/**
*
* Test if two Objects are equal using their equals method.
*
*
* @param lhs the left hand object
* @param rhs the right hand object
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(Object lhs, Object rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
Class lhsClass = lhs.getClass();
if (!lhsClass.isArray()) {
// The simple case, not an array, just test the element
isEquals = lhs.equals(rhs);
}
else if (lhs.getClass() != rhs.getClass()) {
// Here when we compare different dimensions, for example: a boolean[][] to a boolean[]
this.setEquals(false);
}
// 'Switch' on type of array, to dispatch to the correct handler
// This handles multi dimensional arrays of the same depth
else if (lhs instanceof long[]) {
append((long[])lhs, (long[])rhs);
}
else if (lhs instanceof int[]) {
append((int[])lhs, (int[])rhs);
}
else if (lhs instanceof short[]) {
append((short[])lhs, (short[])rhs);
}
else if (lhs instanceof char[]) {
append((char[])lhs, (char[])rhs);
}
else if (lhs instanceof byte[]) {
append((byte[])lhs, (byte[])rhs);
}
else if (lhs instanceof double[]) {
append((double[])lhs, (double[])rhs);
}
else if (lhs instanceof float[]) {
append((float[])lhs, (float[])rhs);
}
else if (lhs instanceof boolean[]) {
append((boolean[])lhs, (boolean[])rhs);
}
else {
// Not an array of primitives
append((Object[])lhs, (Object[])rhs);
}
return this;
}
/**
*
* Test if two long s are equal.
*
*
* @param lhs the left hand long
* @param rhs the right hand long
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(long lhs, long rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Test if two ints are equal.
*
*
* @param lhs the left hand int
* @param rhs the right hand int
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(int lhs, int rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Test if two shorts are equal.
*
*
* @param lhs the left hand short
* @param rhs the right hand short
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(short lhs, short rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Test if two chars are equal.
*
*
* @param lhs the left hand char
* @param rhs the right hand char
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(char lhs, char rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Test if two bytes are equal.
*
*
* @param lhs the left hand byte
* @param rhs the right hand byte
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(byte lhs, byte rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Test if two doubles are equal by testing that the pattern of bits returned by
* doubleToLong are equal.
*
*
* This handles NaNs, Infinities, and -0.0.
*
*
* It is compatible with the hash code generated by HashCodeBuilder.
*
*
* @param lhs the left hand double
* @param rhs the right hand double
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(double lhs, double rhs) {
if (isEquals == false) {
return this;
}
return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
}
/**
*
* Test if two floats are equal byt testing that the pattern of bits returned by
* doubleToLong are equal.
*
*
* This handles NaNs, Infinities, and -0.0.
*
*
* It is compatible with the hash code generated by HashCodeBuilder.
*
*
* @param lhs the left hand float
* @param rhs the right hand float
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(float lhs, float rhs) {
if (isEquals == false) {
return this;
}
return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
}
/**
*
* Test if two booleanss are equal.
*
*
* @param lhs the left hand boolean
* @param rhs the right hand boolean
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(boolean lhs, boolean rhs) {
if (isEquals == false) {
return this;
}
isEquals = (lhs == rhs);
return this;
}
/**
*
* Performs a deep comparison of two Object arrays.
*
*
* This also will be called for the top level of multi-dimensional, ragged, and multi-typed
* arrays.
*
*
* @param lhs the left hand Object[]
* @param rhs the right hand Object[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(Object[] lhs, Object[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of long. Length and all values are compared.
*
*
* The method {@link #append(long, long)} is used.
*
*
* @param lhs the left hand long[]
* @param rhs the right hand long[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(long[] lhs, long[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of int. Length and all values are compared.
*
*
* The method {@link #append(int, int)} is used.
*
*
* @param lhs the left hand int[]
* @param rhs the right hand int[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(int[] lhs, int[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of short. Length and all values are compared.
*
*
* The method {@link #append(short, short)} is used.
*
*
* @param lhs the left hand short[]
* @param rhs the right hand short[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(short[] lhs, short[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of char. Length and all values are compared.
*
*
* The method {@link #append(char, char)} is used.
*
*
* @param lhs the left hand char[]
* @param rhs the right hand char[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(char[] lhs, char[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of byte. Length and all values are compared.
*
*
* The method {@link #append(byte, byte)} is used.
*
*
* @param lhs the left hand byte[]
* @param rhs the right hand byte[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(byte[] lhs, byte[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of double. Length and all values are compared.
*
*
* The method {@link #append(double, double)} is used.
*
*
* @param lhs the left hand double[]
* @param rhs the right hand double[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(double[] lhs, double[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of float. Length and all values are compared.
*
*
* The method {@link #append(float, float)} is used.
*
*
* @param lhs the left hand float[]
* @param rhs the right hand float[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(float[] lhs, float[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Deep comparison of array of boolean. Length and all values are compared.
*
*
* The method {@link #append(boolean, boolean)} is used.
*
*
* @param lhs the left hand boolean[]
* @param rhs the right hand boolean[]
* @return EqualsBuilder - used to chain calls.
*/
public EqualsBuilder append(boolean[] lhs, boolean[] rhs) {
if (isEquals == false) {
return this;
}
if (lhs == rhs) {
return this;
}
if (lhs == null || rhs == null) {
this.setEquals(false);
return this;
}
if (lhs.length != rhs.length) {
this.setEquals(false);
return this;
}
for (int i = 0; i < lhs.length && isEquals; ++i) {
append(lhs[i], rhs[i]);
}
return this;
}
/**
*
* Returns true if the fields that have been checked are all equal.
*
*
* @return boolean
*/
public boolean isEquals() {
return this.isEquals;
}
/**
*
* Returns true if the fields that have been checked are all equal.
*
*
* @return true if all of the fields that have been checked are equal,
* false otherwise.
*/
public Boolean build() {
return Boolean.valueOf(isEquals());
}
/**
* Sets the isEquals value.
*
* @param isEquals The value to set.
*/
protected void setEquals(boolean isEquals) {
this.isEquals = isEquals;
}
/**
* Reset the EqualsBuilder so you can use the same object again
*/
public void reset() {
this.isEquals = true;
}
}