leap.lang.Objects2 Maven / Gradle / Ivy
/*
* Copyright 2013 the original author or authors.
*
* Licensed 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 leap.lang;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
/**
* null safe utils for {@link Object}
*/
public class Objects2 {
public static final int HASH_SEED = 17;
public static final int HASH_OFFSET = 37;
public static final String NULL = "null";
@SuppressWarnings("rawtypes")
public static boolean isEmpty(Object value){
if(null == value){
return true;
}
if(value instanceof CharSequence){
return ((CharSequence) value).length() == 0;
}
if(value instanceof Object[]){
return ((Object[]) value).length == 0;
}
if(value instanceof Collection){
return ((Collection) value).size() == 0;
}
if(value instanceof Map){
return ((Map) value).isEmpty();
}
if(value instanceof Emptiable){
return ((Emptiable) value).isEmpty();
}
if(value.getClass().isArray()){
return Array.getLength(value) == 0;
}
return false;
}
public static String toStringOrEmpty(Object o){
return Objects.toString(o, Strings.EMPTY);
}
public static T firstNotNull(T first, T second) {
return null != first ? first : second;
}
/**
* Convert the given array (which may be a primitive array) to an
* object array (if necessary of primitive wrapper objects).
* A {@code null} source value will be converted to an
* empty Object array.
* @param array the (potentially primitive) array
* @return the corresponding object array (never {@code null})
* @throws IllegalArgumentException if the parameter is not an array
*/
public static Object[] toObjectArray(Object array) {
if (array instanceof Object[]) {
return (Object[]) array;
}
if (array == null) {
return new Object[0];
}
if (!array.getClass().isArray()) {
throw new IllegalArgumentException("Source is not an array: " + array);
}
int length = Array.getLength(array);
if (length == 0) {
return new Object[0];
}
Class wrapperType = Array.get(array, 0).getClass();
Object[] newArray = (Object[]) Array.newInstance(wrapperType, length);
for (int i = 0; i < length; i++) {
newArray[i] = Array.get(array, i);
}
return newArray;
}
/**
* Return a hex String form of an object's identity hash code.
* @param obj the object
* @return the object's identity code in hex notation
*/
//from spring framework
public static String getIdentityHexString(Object obj) {
return Integer.toHexString(System.identityHashCode(obj));
}
public static int hashCode(final int seed, final int hashcode) {
return seed * HASH_OFFSET + hashcode;
}
public static int hashCode(final int seed, final Object obj) {
return hashCode(seed, obj != null ? obj.hashCode() : 0);
}
public static int hashCode(final int seed, final boolean b) {
return hashCode(seed, b ? 1 : 0);
}
protected Objects2(){
}
}