org.apache.wicket.util.lang.Objects Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.wicket.util.lang;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.HashMap;
/**
* Object utilities.
*
* @author Jonathan Locke
*/
public final class Objects
{
/** Type tag meaning java.math.BigDecimal. */
private static final int BIGDEC = 9;
/** Type tag meaning java.math.BigInteger. */
private static final int BIGINT = 6;
/** Type tag meaning boolean. */
private static final int BOOL = 0;
/** Type tag meaning byte. */
private static final int BYTE = 1;
/** Type tag meaning char. */
private static final int CHAR = 2;
/** Type tag meaning double. */
private static final int DOUBLE = 8;
/** Type tag meaning float. */
private static final int FLOAT = 7;
/** Type tag meaning int. */
private static final int INT = 4;
/** Type tag meaning long. */
private static final int LONG = 5;
/**
* The smallest type tag that represents reals as opposed to integers. You can see whether a
* type tag represents reals or integers by comparing the tag to this constant: all tags less
* than this constant represent integers, and all tags greater than or equal to this constant
* represent reals. Of course, you must also check for NONNUMERIC, which means it is not a
* number at all.
*/
private static final int MIN_REAL_TYPE = FLOAT;
/** Type tag meaning something other than a number. */
private static final int NONNUMERIC = 10;
/** Type tag meaning short. */
private static final int SHORT = 3;
/** defaults for primitives. */
private static final HashMap, Object> primitiveDefaults = Generics.newHashMap();
static
{
primitiveDefaults.put(Boolean.TYPE, Boolean.FALSE);
primitiveDefaults.put(Byte.TYPE, (byte)0);
primitiveDefaults.put(Short.TYPE, (short)0);
primitiveDefaults.put(Character.TYPE, (char)0);
primitiveDefaults.put(Integer.TYPE, 0);
primitiveDefaults.put(Long.TYPE, 0L);
primitiveDefaults.put(Float.TYPE, 0.0f);
primitiveDefaults.put(Double.TYPE, 0.0);
primitiveDefaults.put(BigInteger.class, new BigInteger("0"));
primitiveDefaults.put(BigDecimal.class, new BigDecimal(0.0));
}
/**
* Evaluates the given object as a BigDecimal.
*
* @param value
* an object to interpret as a BigDecimal
* @return the BigDecimal value implied by the given object
* @throws NumberFormatException
* if the given object can't be understood as a BigDecimal
*/
public static BigDecimal bigDecValue(final Object value) throws NumberFormatException
{
if (value == null)
{
return BigDecimal.valueOf(0L);
}
Class c = value.getClass();
if (c == BigDecimal.class)
{
return (BigDecimal)value;
}
if (c == BigInteger.class)
{
return new BigDecimal((BigInteger)value);
}
if (c.getSuperclass() == Number.class)
{
return new BigDecimal(((Number)value).doubleValue());
}
if (c == Boolean.class)
{
return BigDecimal.valueOf((Boolean)value ? 1 : 0);
}
if (c == Character.class)
{
return BigDecimal.valueOf(((Character)value).charValue());
}
return new BigDecimal(stringValue(value, true));
}
/**
* Evaluates the given object as a BigInteger.
*
* @param value
* an object to interpret as a BigInteger
* @return the BigInteger value implied by the given object
* @throws NumberFormatException
* if the given object can't be understood as a BigInteger
*/
public static BigInteger bigIntValue(final Object value) throws NumberFormatException
{
if (value == null)
{
return BigInteger.valueOf(0L);
}
Class c = value.getClass();
if (c == BigInteger.class)
{
return (BigInteger)value;
}
if (c == BigDecimal.class)
{
return ((BigDecimal)value).toBigInteger();
}
if (c.getSuperclass() == Number.class)
{
return BigInteger.valueOf(((Number)value).longValue());
}
if (c == Boolean.class)
{
return BigInteger.valueOf((Boolean)value ? 1 : 0);
}
if (c == Character.class)
{
return BigInteger.valueOf((Character)value);
}
return new BigInteger(stringValue(value, true));
}
/**
* Evaluates the given object as a boolean: if it is a Boolean object, it's easy; if it's a
* Number or a Character, returns true for non-zero objects; and otherwise returns true for
* non-null objects.
*
* @param value
* an object to interpret as a boolean
* @return the boolean value implied by the given object
*/
public static boolean booleanValue(final Object value)
{
if (value == null)
{
return false;
}
Class c = value.getClass();
if (c == Boolean.class)
{
return (Boolean)value;
}
if (c == Character.class)
{
return (Character)value != 0;
}
if (value instanceof Number)
{
return ((Number)value).doubleValue() != 0;
}
return true; // non-null
}
/**
* Compares two objects for equality, even if it has to convert one of them to the other type.
* If both objects are numeric they are converted to the widest type and compared. If one is
* non-numeric and one is numeric the non-numeric is converted to double and compared to the
* double numeric value. If both are non-numeric and Comparable and the types are compatible
* (i.e. v1 is of the same or superclass of v2's type) they are compared with
* Comparable.compareTo(). If both values are non-numeric and not Comparable or of incompatible
* classes this will throw and IllegalArgumentException.
*
* @param v1
* First value to compare
* @param v2
* second value to compare
*
* @return integer describing the comparison between the two objects. A negative number
* indicates that v1 < v2. Positive indicates that v1 > v2. Zero indicates v1 == v2.
*
* @throws IllegalArgumentException
* if the objects are both non-numeric yet of incompatible types or do not implement
* Comparable.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static int compareWithConversion(final Object v1, final Object v2)
{
int result;
if (v1 == v2)
{
result = 0;
}
else
{
int t1 = getNumericType(v1), t2 = getNumericType(v2), type = getNumericType(t1, t2,
true);
switch (type)
{
case BIGINT :
result = bigIntValue(v1).compareTo(bigIntValue(v2));
break;
case BIGDEC :
result = bigDecValue(v1).compareTo(bigDecValue(v2));
break;
case NONNUMERIC :
if ((t1 == NONNUMERIC) && (t2 == NONNUMERIC))
{
if ((v1 instanceof Comparable) &&
v1.getClass().isAssignableFrom(v2.getClass()))
{
result = ((Comparable)v1).compareTo(v2);
break;
}
else
{
throw new IllegalArgumentException("invalid comparison: " +
v1.getClass().getName() + " and " + v2.getClass().getName());
}
}
// else fall through
case FLOAT :
case DOUBLE :
double dv1 = doubleValue(v1),
dv2 = doubleValue(v2);
return (dv1 == dv2) ? 0 : ((dv1 < dv2) ? -1 : 1);
default :
long lv1 = longValue(v1),
lv2 = longValue(v2);
return (lv1 == lv2) ? 0 : ((lv1 < lv2) ? -1 : 1);
}
}
return result;
}
/**
* Convert between basic Java types, i.e. primitives and their wrappers, numbers and strings.
*
* This method also detects when arrays are being converted and converts the components of one
* array to the type of the other.
*
* @param
* target type
* @param value
* an object to be converted to the given type
* @param toType
* class type to be converted to
* @return converted value of the type given, or null if the value cannot be converted to the
* given type.
*/
public static T convertValue(final Object value, final Class toType)
{
Object result = null;
if (value != null)
{
/* If array -> array then convert components of array individually */
if (value.getClass().isArray() && toType.isArray())
{
Class componentType = toType.getComponentType();
result = Array.newInstance(componentType, Array.getLength(value));
for (int i = 0, icount = Array.getLength(value); i < icount; i++)
{
Array.set(result, i, convertValue(Array.get(value, i), componentType));
}
}
else
{
if ((toType == Integer.class) || (toType == Integer.TYPE))
{
result = (int)longValue(value);
}
if ((toType == Double.class) || (toType == Double.TYPE))
{
result = doubleValue(value);
}
if ((toType == Boolean.class) || (toType == Boolean.TYPE))
{
result = booleanValue(value) ? Boolean.TRUE : Boolean.FALSE;
}
if ((toType == Byte.class) || (toType == Byte.TYPE))
{
result = (byte)longValue(value);
}
if ((toType == Character.class) || (toType == Character.TYPE))
{
result = (char)longValue(value);
}
if ((toType == Short.class) || (toType == Short.TYPE))
{
result = (short)longValue(value);
}
if ((toType == Long.class) || (toType == Long.TYPE))
{
result = longValue(value);
}
if ((toType == Float.class) || (toType == Float.TYPE))
{
result = new Float(doubleValue(value));
}
if (toType == BigInteger.class)
{
result = bigIntValue(value);
}
if (toType == BigDecimal.class)
{
result = bigDecValue(value);
}
if (toType == String.class)
{
result = stringValue(value);
}
}
}
else
{
if (toType.isPrimitive())
{
result = primitiveDefaults.get(toType);
}
}
@SuppressWarnings("unchecked")
T finalResult = (T)result;
return finalResult;
}
/**
* Evaluates the given object as a double-precision floating-point number.
*
* @param value
* an object to interpret as a double
* @return the double value implied by the given object
* @throws NumberFormatException
* if the given object can't be understood as a double
*/
public static double doubleValue(final Object value) throws NumberFormatException
{
if (value == null)
{
return 0.0;
}
Class c = value.getClass();
if (c.getSuperclass() == Number.class)
{
return ((Number)value).doubleValue();
}
if (c == Boolean.class)
{
return (Boolean)value ? 1 : 0;
}
if (c == Character.class)
{
return (Character)value;
}
String s = stringValue(value, true);
return (s.length() == 0) ? 0.0 : Double.parseDouble(s);
}
/**
* Returns true if a and b are equal. Either object may be null.
*
* @param a
* Object a
* @param b
* Object b
* @return True if the objects are equal
*/
public static boolean equal(final Object a, final Object b)
{
if (a == b)
{
return true;
}
if ((a != null) && (b != null) && a.equals(b))
{
return true;
}
return false;
}
/**
* Returns the constant from the NumericTypes interface that best expresses the type of an
* operation, which can be either numeric or not, on the two given types.
*
* @param t1
* type of one argument to an operator
* @param t2
* type of the other argument
* @param canBeNonNumeric
* whether the operator can be interpreted as non-numeric
* @return the appropriate constant from the NumericTypes interface
*/
public static int getNumericType(int t1, int t2, final boolean canBeNonNumeric)
{
if (t1 == t2)
{
return t1;
}
if (canBeNonNumeric &&
((t1 == NONNUMERIC) || (t2 == NONNUMERIC) || (t1 == CHAR) || (t2 == CHAR)))
{
return NONNUMERIC;
}
if (t1 == NONNUMERIC)
{
t1 = DOUBLE; // Try to interpret strings as doubles...
}
if (t2 == NONNUMERIC)
{
t2 = DOUBLE; // Try to interpret strings as doubles...
}
if (t1 >= MIN_REAL_TYPE)
{
if (t2 >= MIN_REAL_TYPE)
{
return Math.max(t1, t2);
}
if (t2 < INT)
{
return t1;
}
if (t2 == BIGINT)
{
return BIGDEC;
}
return Math.max(DOUBLE, t1);
}
else if (t2 >= MIN_REAL_TYPE)
{
if (t1 < INT)
{
return t2;
}
if (t1 == BIGINT)
{
return BIGDEC;
}
return Math.max(DOUBLE, t2);
}
else
{
return Math.max(t1, t2);
}
}
/**
* Returns a constant from the NumericTypes interface that represents the numeric type of the
* given object.
*
* @param value
* an object that needs to be interpreted as a number
* @return the appropriate constant from the NumericTypes interface
*/
public static int getNumericType(final Object value)
{
if (value != null)
{
Class c = value.getClass();
if (c == Integer.class)
{
return INT;
}
if (c == Double.class)
{
return DOUBLE;
}
if (c == Boolean.class)
{
return BOOL;
}
if (c == Byte.class)
{
return BYTE;
}
if (c == Character.class)
{
return CHAR;
}
if (c == Short.class)
{
return SHORT;
}
if (c == Long.class)
{
return LONG;
}
if (c == Float.class)
{
return FLOAT;
}
if (c == BigInteger.class)
{
return BIGINT;
}
if (c == BigDecimal.class)
{
return BIGDEC;
}
}
return NONNUMERIC;
}
/**
* Returns the constant from the NumericTypes interface that best expresses the type of a
* numeric operation on the two given objects.
*
* @param v1
* one argument to a numeric operator
* @param v2
* the other argument
* @return the appropriate constant from the NumericTypes interface
*/
public static int getNumericType(final Object v1, final Object v2)
{
return getNumericType(v1, v2, false);
}
/**
* Returns the constant from the NumericTypes interface that best expresses the type of an
* operation, which can be either numeric or not, on the two given objects.
*
* @param v1
* one argument to an operator
* @param v2
* the other argument
* @param canBeNonNumeric
* whether the operator can be interpreted as non-numeric
* @return the appropriate constant from the NumericTypes interface
*/
public static int getNumericType(final Object v1, final Object v2, final boolean canBeNonNumeric)
{
return getNumericType(getNumericType(v1), getNumericType(v2), canBeNonNumeric);
}
/**
* Returns true if object1 is equal to object2 in either the sense that they are the same object
* or, if both are non-null if they are equal in the equals() sense.
*
* @param object1
* First object to compare
* @param object2
* Second object to compare
*
* @return true if v1 == v2
*/
public static boolean isEqual(final Object object1, final Object object2)
{
boolean result = false;
if (object1 == object2)
{
result = true;
}
else
{
if ((object1 != null) && object1.getClass().isArray())
{
if ((object2 != null) && object2.getClass().isArray() &&
(object2.getClass() == object1.getClass()))
{
result = (Array.getLength(object1) == Array.getLength(object2));
if (result)
{
for (int i = 0, icount = Array.getLength(object1); result && (i < icount); i++)
{
result = isEqual(Array.get(object1, i), Array.get(object2, i));
}
}
}
}
else
{
// Check for converted equivalence first, then equals()
// equivalence
result = (object1 != null) && (object2 != null) &&
((compareWithConversion(object1, object2) == 0) || object1.equals(object2));
}
}
return result;
}
/**
* Evaluates the given object as a long integer.
*
* @param value
* an object to interpret as a long integer
* @return the long integer value implied by the given object
* @throws NumberFormatException
* if the given object can't be understood as a long integer
*/
public static long longValue(final Object value) throws NumberFormatException
{
if (value == null)
{
return 0L;
}
Class c = value.getClass();
if (c.getSuperclass() == Number.class)
{
return ((Number)value).longValue();
}
if (c == Boolean.class)
{
return (Boolean)value ? 1 : 0;
}
if (c == Character.class)
{
return (Character)value;
}
return Long.parseLong(stringValue(value, true));
}
/**
* Returns a new Number object of an appropriate type to hold the given integer value. The type
* of the returned object is consistent with the given type argument, which is a constant from
* the NumericTypes interface.
*
* @param type
* the nominal numeric type of the result, a constant from the NumericTypes interface
* @param value
* the integer value to convert to a Number object
* @return a Number object with the given value, of type implied by the type argument
*/
public static Number newInteger(final int type, final long value)
{
switch (type)
{
case BOOL :
case CHAR :
case INT :
return (int)value;
case FLOAT :
return (float)value;
case DOUBLE :
return (double)value;
case LONG :
return value;
case BYTE :
return (byte)value;
case SHORT :
return (short)value;
default :
return BigInteger.valueOf(value);
}
}
/**
* Evaluates the given object as a String.
*
* @param value
* an object to interpret as a String
* @return the String value implied by the given object as returned by the toString() method, or
* "null" if the object is null.
*/
public static String stringValue(final Object value)
{
return stringValue(value, false);
}
/**
* returns hashcode of the objects by calling obj.hashcode(). safe to use when obj is null.
*
* @param obj
* @return hashcode of the object or 0 if obj is null
*/
public static int hashCode(final Object... obj)
{
if ((obj == null) || (obj.length == 0))
{
return 0;
}
int result = 37;
for (int i = obj.length - 1; i > -1; i--)
{
result = 37 * result + (obj[i] != null ? obj[i].hashCode() : 0);
}
return result;
}
/**
* Evaluates the given object as a String and trims it if the trim flag is true.
*
* @param value
* an object to interpret as a String
* @param trim
* whether to trim the string
* @return the String value implied by the given object as returned by the toString() method, or
* "null" if the object is null.
*/
public static String stringValue(final Object value, final boolean trim)
{
String result;
if (value == null)
{
result = "null";
}
else
{
result = value.toString();
if (trim)
{
result = result.trim();
}
}
return result;
}
/**
* Returns the original object if this one is != null. If the original object is null
* the default one is returned. The default object has no restriction, it might be itself null.
*
* @param originalObj
* the original object
* @param defaultObj
* the default object
* @return the original object if not null, the default one otherwise.
*/
public static T defaultIfNull(T originalObj, T defaultObj)
{
return originalObj != null ? originalObj : defaultObj;
}
/**
* Instantiation not allowed
*/
private Objects()
{
}
}