Java Doc for CompareToBuilder.java in  » Library » Apache-common-lang » org » apache » commons » lang » builder » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Two Objects that compare equal using equals(Object) should normally also compare equal using compareTo(Object).

All relevant fields should be included in the calculation of the comparison. Derived fields may be ignored. The same fields, in the same order, should be used in both compareTo(Object) and equals(Object).

To use this class write code as follows:

 public class MyClass {
 String field1;
 int field2;
 boolean field3;
 ...
 public int compareTo(Object o) {
 MyClass myClass = (MyClass) o;
 return new CompareToBuilder()
 .appendSuper(super.compareTo(o)
 .append(this.field1, myClass.field1)
 .append(this.field2, myClass.field2)
 .append(this.field3, myClass.field3)
 .toComparison();
 }
 }
 

Alternatively, there are CompareToBuilder.reflectionCompare(Object,Object) reflectionCompare methods that use reflection to determine the fields to append. Because fields can be private, reflectionCompare uses java.lang.reflect.AccessibleObject.setAccessible(boolean) to bypass normal access control checks. This will fail under a security manager, unless the appropriate permissions are set up correctly. It is also slower than appending explicitly.

A typical implementation of compareTo(Object) using reflectionCompare looks like:

 public int compareTo(Object o) {
 return CompareToBuilder.reflectionCompare(this, o);
 }
 

Constructor for CompareToBuilder.

Starts off assuming that the objects are equal.

Appends to the builder the comparison of two Objects.

1. Check if lhs == rhs
2. Check if either lhs or rhs is null, a null object is less than a non-null object
3. Check the object contents

If lhs is an array, array comparison methods will be used.

Appends to the builder the deep comparison of two Object arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a short length array is less than a long length array
4. Check array contents element by element using CompareToBuilder.append(Object,Object,Comparator)

This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks.

Constructor for CompareToBuilder.

Starts off assuming that the objects are equal. Multiple calls are then made to the various append methods, followed by a call to CompareToBuilder.toComparison to get the result.

Appends to the builder the comparison of two Objects.

1. Check if lhs == rhs
2. Check if either lhs or rhs is null, a null object is less than a non-null object
3. Check the object contents

lhs must either be an array or implement Comparable .

Appends to the builder the comparison of two Objects.

1. Check if lhs == rhs
2. Check if either lhs or rhs is null, a null object is less than a non-null object
3. Check the object contents

If lhs is an array, array comparison methods will be used. Otherwise comparator will be used to compare the objects. If comparator is null, lhs must implement Comparable instead.

Appends to the builder the comparison of two doubles.

This handles NaNs, Infinities, and -0.0.

It is compatible with the hash code generated by HashCodeBuilder.

Appends to the builder the comparison of two floats.

This handles NaNs, Infinities, and -0.0.

It is compatible with the hash code generated by HashCodeBuilder.

Appends to the builder the deep comparison of two Object arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a short length array is less than a long length array
4. Check array contents element by element using CompareToBuilder.append(Object,Object,Comparator)

This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.

Appends to the builder the deep comparison of two Object arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a short length array is less than a long length array
4. Check array contents element by element using CompareToBuilder.append(Object,Object,Comparator)

This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.

Appends to the builder the deep comparison of two long arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(long,long)

Appends to the builder the deep comparison of two int arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(int,int)

Appends to the builder the deep comparison of two short arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(short,short)

Appends to the builder the deep comparison of two char arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(char,char)

Appends to the builder the deep comparison of two byte arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(byte,byte)

Appends to the builder the deep comparison of two double arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(double,double)

Appends to the builder the deep comparison of two float arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(float,float)

Appends to the builder the deep comparison of two boolean arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using CompareToBuilder.append(boolean,boolean)

Appends to the builder the compareTo(Object) result of the superclass.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• Transient members will be not be compared, as they are likely derived fields
• Superclass fields will be compared

If both lhs and rhs are null, they are considered equal.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• If compareTransients is true, compares transient members. Otherwise ignores them, as they are likely derived fields.
• Superclass fields will be compared

If both lhs and rhs are null, they are considered equal.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• If compareTransients is true, compares transient members. Otherwise ignores them, as they are likely derived fields.
• Superclass fields will be compared

If both lhs and rhs are null, they are considered equal.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• If compareTransients is true, compares transient members. Otherwise ignores them, as they are likely derived fields.
• Superclass fields will be compared

If both lhs and rhs are null, they are considered equal.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• If the compareTransients is true, compares transient members. Otherwise ignores them, as they are likely derived fields.
• Compares superclass fields up to and including reflectUpToClass. If reflectUpToClass is null, compares all superclass fields.

If both lhs and rhs are null, they are considered equal.

Compares two Objects via reflection.

Fields can be private, thus AccessibleObject.setAccessible is used to bypass normal access control checks. This will fail under a security manager unless the appropriate permissions are set.

• Static fields will not be compared
• If the compareTransients is true, compares transient members. Otherwise ignores them, as they are likely derived fields.
• Compares superclass fields up to and including reflectUpToClass. If reflectUpToClass is null, compares all superclass fields.

If both lhs and rhs are null, they are considered equal.