ArrayUtils，ListUtils，MapUtils，ObjectUtils，SystemUtils
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ArrayUtils
数组工具类，可用于数组常用操作，如：
isEmpty(V[] sourceArray) 判断数组是否为空或长度为0
getLast(V[] sourceArray, V value, V defaultValue, boolean isCircle) 得到数组中某个元素前一个元素，isCircle表示是否循环
getNext(V[] sourceArray, V value, V defaultValue, boolean isCircle) 得到数组中某个元素下一个元素，isCircle表示是否循环
/**
* Array Utils
*
- {@link #isEmpty(Object[])} is null or its length is 0
- {@link #getLast(Object[], Object, Object, boolean)} get last element of the target element, before the first one
* that match the target element front to back - {@link #getNext(Object[], Object, Object, boolean)} get next element of the target element, after the first one
* that match the target element front to back - {@link #getLast(Object[], Object, boolean)}
- {@link #getLast(int[], int, int, boolean)}
- {@link #getLast(long[], long, long, boolean)}
- {@link #getNext(Object[], Object, boolean)}
- {@link #getNext(int[], int, int, boolean)}
- {@link #getNext(long[], long, long, boolean)}
*
*
*
*
*
*
*
*
*
*
*/
public class ArrayUtils {
private ArrayUtils() {
throw new AssertionError();
}
/**
* is null or its length is 0
*
* @param
* @param sourceArray
* @return
*/
public static
return (sourceArray == null || sourceArray.length == 0);
}
/**
* get last element of the target element, before the first one that match the target element front to back
*
- if array is empty, return defaultValue
- if target element is not exist in array, return defaultValue
- if target element exist in array and its index is not 0, return the last element
- if target element exist in array and its index is 0, return the last one in array if isCircle is true, else
* return defaultValue
*
*
*
*
*
*
* @param
* @param sourceArray
* @param value value of target element
* @param defaultValue default return value
* @param isCircle whether is circle
* @return
*/
public static
if (isEmpty(sourceArray)) {
return defaultValue;
}
int currentPosition = -1;
for (int i = 0; i < sourceArray.length; i++) {
if (ObjectUtils.isEquals(value, sourceArray[i])) {
currentPosition = i;
break;
}
}
if (currentPosition == -1) {
return defaultValue;
}
if (currentPosition == 0) {
return isCircle ? sourceArray[sourceArray.length - 1] : defaultValue;
}
return sourceArray[currentPosition - 1];
}
/**
* get next element of the target element, after the first one that match the target element front to back
*
- if array is empty, return defaultValue
- if target element is not exist in array, return defaultValue
- if target element exist in array and not the last one in array, return the next element
- if target element exist in array and the last one in array, return the first one in array if isCircle is
* true, else return defaultValue
*
*
*
*
*
*
* @param
* @param sourceArray
* @param value value of target element
* @param defaultValue default return value
* @param isCircle whether is circle
* @return
*/
public static
if (isEmpty(sourceArray)) {
return defaultValue;
}
int currentPosition = -1;
for (int i = 0; i < sourceArray.length; i++) {
if (ObjectUtils.isEquals(value, sourceArray[i])) {
currentPosition = i;
break;
}
}
if (currentPosition == -1) {
return defaultValue;
}
if (currentPosition == sourceArray.length - 1) {
return isCircle ? sourceArray[0] : defaultValue;
}
return sourceArray[currentPosition + 1];
}
/**
* @see {@link ArrayUtils#getLast(Object[], Object, Object, boolean)} defaultValue is null
*/
public static
return getLast(sourceArray, value, null, isCircle);
}
/**
* @see {@link ArrayUtils#getNext(Object[], Object, Object, boolean)} defaultValue is null
*/
public static
return getNext(sourceArray, value, null, isCircle);
}
/**
* @see {@link ArrayUtils#getLast(Object[], Object, Object, boolean)} Object is Long
*/
public static long getLast(long[] sourceArray, long value, long defaultValue, boolean isCircle) {
if (sourceArray.length == 0) {
throw new IllegalArgumentException("The length of source array must be greater than 0.");
}
Long[] array = ObjectUtils.transformLongArray(sourceArray);
return getLast(array, value, defaultValue, isCircle);
}
/**
* @see {@link ArrayUtils#getNext(Object[], Object, Object, boolean)} Object is Long
*/
public static long getNext(long[] sourceArray, long value, long defaultValue, boolean isCircle) {
if (sourceArray.length == 0) {
throw new IllegalArgumentException("The length of source array must be greater than 0.");
}
Long[] array = ObjectUtils.transformLongArray(sourceArray);
return getNext(array, value, defaultValue, isCircle);
}
/**
* @see {@link ArrayUtils#getLast(Object[], Object, Object, boolean)} Object is Integer
*/
public static int getLast(int[] sourceArray, int value, int defaultValue, boolean isCircle) {
if (sourceArray.length == 0) {
throw new IllegalArgumentException("The length of source array must be greater than 0.");
}
Integer[] array = ObjectUtils.transformIntArray(sourceArray);
return getLast(array, value, defaultValue, isCircle);
}
/**
* @see {@link ArrayUtils#getNext(Object[], Object, Object, boolean)} Object is Integer
*/
public static int getNext(int[] sourceArray, int value, int defaultValue, boolean isCircle) {
if (sourceArray.length == 0) {
throw new IllegalArgumentException("The length of source array must be greater than 0.");
}
Integer[] array = ObjectUtils.transformIntArray(sourceArray);
return getNext(array, value, defaultValue, isCircle);
}
}
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ListUtils
List工具类，可用于List常用操作，如：
isEmpty(List sourceList) 判断List是否为空或长度为0
join(List list, String separator) List转换为字符串，并以固定分隔符分割
addDistinctEntry(List sourceList, V entry) 向list中添加不重复元素
import java.util.ArrayList;
import java.util.List;
import android.text.TextUtils;
/**
* List Utils
*/
public class ListUtils {
/** default join separator **/
public static final String DEFAULT_JOIN_SEPARATOR = ",";
private ListUtils() {
throw new AssertionError();
}
/**
* get size of list
*
*
* getSize(null) = 0;
* getSize({}) = 0;
* getSize({1}) = 1;
*
*
* @param
* @param sourceList
* @return if list is null or empty, return 0, else return {@link List#size()}.
*/
public static
return sourceList == null ? 0 : sourceList.size();
}
/**
* is null or its size is 0
*
*
* isEmpty(null) = true;
* isEmpty({}) = true;
* isEmpty({1}) = false;
*
*
* @param
* @param sourceList
* @return if list is null or its size is 0, return true, else return false.
*/
public static
return (sourceList == null || sourceList.size() == 0);
}
/**
* compare two list
*
*
* isEquals(null, null) = true;
* isEquals(new ArrayList<String>(), null) = false;
* isEquals(null, new ArrayList<String>()) = false;
* isEquals(new ArrayList<String>(), new ArrayList<String>()) = true;
*
*
* @param
* @param actual
* @param expected
* @return
*/
public static
if (actual == null) {
return expected == null;
}
if (expected == null) {
return false;
}
if (actual.size() != expected.size()) {
return false;
}
for (int i = 0; i < actual.size(); i++) {
if (!ObjectUtils.isEquals(actual.get(i), expected.get(i))) {
return false;
}
}
return true;
}
/**
* join list to string, separator is ","
*
*
* join(null) = "";
* join({}) = "";
* join({a,b}) = "a,b";
*
*
* @param list
* @return join list to string, separator is ",". if list is empty, return ""
*/
public static String join(List
return join(list, DEFAULT_JOIN_SEPARATOR);
}
/**
* join list to string
*
*
* join(null, '#') = "";
* join({}, '#') = "";
* join({a,b,c}, ' ') = "abc";
* join({a,b,c}, '#') = "a#b#c";
*
*
* @param list
* @param separator
* @return join list to string. if list is empty, return ""
*/
public static String join(List
return join(list, new String(new char[] {separator}));
}
/**
* join list to string. if separator is null, use {@link #DEFAULT_JOIN_SEPARATOR}
*
*
* join(null, "#") = "";
* join({}, "#$") = "";
* join({a,b,c}, null) = "a,b,c";
* join({a,b,c}, "") = "abc";
* join({a,b,c}, "#") = "a#b#c";
* join({a,b,c}, "#$") = "a#$b#$c";
*
*
* @param list
* @param separator
* @return join list to string with separator. if list is empty, return ""
*/
public static String join(List
return list == null ? "" : TextUtils.join(separator, list);
}
/**
* add distinct entry to list
*
* @param
* @param sourceList
* @param entry
* @return if entry already exist in sourceList, return false, else add it and return true.
*/
public static
return (sourceList != null && !sourceList.contains(entry)) ? sourceList.add(entry) : false;
}
/**
* add all distinct entry to list1 from list2
*
* @param
* @param sourceList
* @param entryList
* @return the count of entries be added
*/
public static
if (sourceList == null || isEmpty(entryList)) {
return 0;
}
int sourceCount = sourceList.size();
for (V entry : entryList) {
if (!sourceList.contains(entry)) {
sourceList.add(entry);
}
}
return sourceList.size() - sourceCount;
}
/**
* remove duplicate entries in list
*
* @param
* @param sourceList
* @return the count of entries be removed
*/
public static
if (isEmpty(sourceList)) {
return 0;
}
int sourceCount = sourceList.size();
int sourceListSize = sourceList.size();
for (int i = 0; i < sourceListSize; i++) {
for (int j = (i + 1); j < sourceListSize; j++) {
if (sourceList.get(i).equals(sourceList.get(j))) {
sourceList.remove(j);
sourceListSize = sourceList.size();
j--;
}
}
}
return sourceCount - sourceList.size();
}
/**
* add not null entry to list
*
* @param sourceList
* @param value
* @return
- if sourceList is null, return false
- if value is null, return false
- return {@link List#add(Object)}
*
*
*
*
*/
public static
return (sourceList != null && value != null) ? sourceList.add(value) : false;
}
/**
* @see {@link ArrayUtils#getLast(Object[], Object, Object, boolean)} defaultValue is null, isCircle is true
*/
@SuppressWarnings("unchecked")
public static
return (sourceList == null) ? null : (V)ArrayUtils.getLast(sourceList.toArray(), value, true);
}
/**
* @see {@link ArrayUtils#getNext(Object[], Object, Object, boolean)} defaultValue is null, isCircle is true
*/
@SuppressWarnings("unchecked")
public static
return (sourceList == null) ? null : (V)ArrayUtils.getNext(sourceList.toArray(), value, true);
}
/**
* invert list
*
* @param
* @param sourceList
* @return
*/
public static
if (isEmpty(sourceList)) {
return sourceList;
}
List
for (int i = sourceList.size() - 1; i >= 0; i--) {
invertList.add(sourceList.get(i));
}
return invertList;
}
}
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MapUtils
Map工具类，可用于Map常用操作，如：
isEmpty(Map
toJson(Map
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import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
/**
* Map Utils
*/
public class MapUtils {
/** default separator between key and value **/
public static final String DEFAULT_KEY_AND_VALUE_SEPARATOR = ":";
/** default separator between key-value pairs **/
public static final String DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR = ",";
private MapUtils() {
throw new AssertionError();
}
/**
* is null or its size is 0
*
*
* isEmpty(null) = true;
* isEmpty({}) = true;
* isEmpty({1, 2}) = false;
*
*
* @param sourceMap
* @return if map is null or its size is 0, return true, else return false.
*/
public static
return (sourceMap == null || sourceMap.size() == 0);
}
/**
* add key-value pair to map, and key need not null or empty
*
* @param map
* @param key
* @param value
* @return
- if map is null, return false
- if key is null or empty, return false
- return {@link Map#put(Object, Object)}
*
*
*
*
*/
public static boolean putMapNotEmptyKey(Map
if (map == null || StringUtils.isEmpty(key)) {
return false;
}
map.put(key, value);
return true;
}
/**
* add key-value pair to map, both key and value need not null or empty
*
* @param map
* @param key
* @param value
* @return
- if map is null, return false
- if key is null or empty, return false
- if value is null or empty, return false
- return {@link Map#put(Object, Object)}
*
*
*
*
*
*/
public static boolean putMapNotEmptyKeyAndValue(Map
if (map == null || StringUtils.isEmpty(key) || StringUtils.isEmpty(value)) {
return false;
}
map.put(key, value);
return true;
}
/**
* add key-value pair to map, key need not null or empty
*
* @param map
* @param key
* @param value
* @param defaultValue
* @return
- if map is null, return false
- if key is null or empty, return false
- if value is null or empty, put defaultValue, return true
- if value is neither null nor empty，put value, return true
*
*
*
*
*
*/
public static boolean putMapNotEmptyKeyAndValue(Map
String defaultValue) {
if (map == null || StringUtils.isEmpty(key)) {
return false;
}
map.put(key, StringUtils.isEmpty(value) ? defaultValue : value);
return true;
}
/**
* add key-value pair to map, key need not null
*
* @param map
* @param key
* @param value
* @return
- if map is null, return false
- if key is null, return false
- return {@link Map#put(Object, Object)}
*
*
*
*
*/
public static
if (map == null || key == null) {
return false;
}
map.put(key, value);
return true;
}
/**
* add key-value pair to map, both key and value need not null
*
* @param map
* @param key
* @param value
* @return
- if map is null, return false
- if key is null, return false
- if value is null, return false
- return {@link Map#put(Object, Object)}
*
*
*
*
*
*/
public static
if (map == null || key == null || value == null) {
return false;
}
map.put(key, value);
return true;
}
/**
* get key by value, match the first entry front to back
*
- for HashMap, the order of entry not same to put order, so you may need to use TreeMap
* Attentions:
*
*
*
* @param
* @param map
* @param value
* @return
- if map is null, return null
- if value exist, return key
- return null
*
*
*
*
*/
public static
if (isEmpty(map)) {
return null;
}
for (Entry
if (ObjectUtils.isEquals(entry.getValue(), value)) {
return entry.getKey();
}
}
return null;
}
/**
* parse key-value pairs to map, ignore empty key
*
*
* parseKeyAndValueToMap("","","",true)=null
* parseKeyAndValueToMap(null,"","",true)=null
* parseKeyAndValueToMap("a:b,:","","",true)={(a,b)}
* parseKeyAndValueToMap("a:b,:d","","",true)={(a,b)}
* parseKeyAndValueToMap("a:b,c:d","","",true)={(a,b),(c,d)}
* parseKeyAndValueToMap("a=b, c = d","=",",",true)={(a,b),(c,d)}
* parseKeyAndValueToMap("a=b, c = d","=",",",false)={(a, b),( c , d)}
* parseKeyAndValueToMap("a=b, c=d","=", ",", false)={(a,b),( c,d)}
* parseKeyAndValueToMap("a=b; c=d","=", ";", false)={(a,b),( c,d)}
* parseKeyAndValueToMap("a=b, c=d", ",", ";", false)={(a=b, c=d)}
*
*
* @param source key-value pairs
* @param keyAndValueSeparator separator between key and value
* @param keyAndValuePairSeparator separator between key-value pairs
* @param ignoreSpace whether ignore space at the begging or end of key and value
* @return
*/
public static Map
String keyAndValuePairSeparator, boolean ignoreSpace) {
if (StringUtils.isEmpty(source)) {
return null;
}
if (StringUtils.isEmpty(keyAndValueSeparator)) {
keyAndValueSeparator = DEFAULT_KEY_AND_VALUE_SEPARATOR;
}
if (StringUtils.isEmpty(keyAndValuePairSeparator)) {
keyAndValuePairSeparator = DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR;
}
Map
String[] keyAndValueArray = source.split(keyAndValuePairSeparator);
if (keyAndValueArray == null) {
return null;
}
int seperator;
for (String valueEntity : keyAndValueArray) {
if (!StringUtils.isEmpty(valueEntity)) {
seperator = valueEntity.indexOf(keyAndValueSeparator);
if (seperator != -1) {
if (ignoreSpace) {
MapUtils.putMapNotEmptyKey(keyAndValueMap, valueEntity.substring(0, seperator).trim(),
valueEntity.substring(seperator + 1).trim());
} else {
MapUtils.putMapNotEmptyKey(keyAndValueMap, valueEntity.substring(0, seperator),
valueEntity.substring(seperator + 1));
}
}
}
}
return keyAndValueMap;
}
/**
* parse key-value pairs to map, ignore empty key
*
* @param source key-value pairs
* @param ignoreSpace whether ignore space at the begging or end of key and value
* @return
* @see {@link MapUtils#parseKeyAndValueToMap(String, String, String, boolean)}, keyAndValueSeparator is
* {@link #DEFAULT_KEY_AND_VALUE_SEPARATOR}, keyAndValuePairSeparator is
* {@link #DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR}
*/
public static Map
return parseKeyAndValueToMap(source, DEFAULT_KEY_AND_VALUE_SEPARATOR, DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR,
ignoreSpace);
}
/**
* parse key-value pairs to map, ignore empty key, ignore space at the begging or end of key and value
*
* @param source key-value pairs
* @return
* @see {@link MapUtils#parseKeyAndValueToMap(String, String, String, boolean)}, keyAndValueSeparator is
* {@link #DEFAULT_KEY_AND_VALUE_SEPARATOR}, keyAndValuePairSeparator is
* {@link #DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR}, ignoreSpace is true
*/
public static Map
return parseKeyAndValueToMap(source, DEFAULT_KEY_AND_VALUE_SEPARATOR, DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR,
true);
}
/**
* join map
*
* @param map
* @return
*/
public static String toJson(Map
if (map == null || map.size() == 0) {
return null;
}
StringBuilder paras = new StringBuilder();
paras.append("{");
Iterator
while (ite.hasNext()) {
Map.Entry
paras.append("\"").append(entry.getKey()).append("\":\"").append(entry.getValue()).append("\"");
if (ite.hasNext()) {
paras.append(",");
}
}
paras.append("}");
return paras.toString();
}
}
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ObjectUtils
Object工具类，可用于Object常用操作，如：
isEquals(Object actual, Object expected) 比较两个对象是否相等
compare(V v1, V v2) 比较两个对象大小
transformIntArray(int[] source) Integer 数组转换为int数组
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public class ObjectUtils {
private ObjectUtils() {
throw new AssertionError();
}
/**
* compare two object
*
* @param actual
* @param expected
* @return
- if both are null, return true
- return actual.{@link Object#equals(Object)}
*
*
*
*/
public static boolean isEquals(Object actual, Object expected) {
return actual == expected || (actual == null ? expected == null : actual.equals(expected));
}
/**
* null Object to empty string
*
*
* nullStrToEmpty(null) = "";
* nullStrToEmpty("") = "";
* nullStrToEmpty("aa") = "aa";
*
*
* @param str
* @return
*/
public static String nullStrToEmpty(Object str) {
return (str == null ? "" : (str instanceof String ? (String)str : str.toString()));
}
/**
* convert long array to Long array
*
* @param source
* @return
*/
public static Long[] transformLongArray(long[] source) {
Long[] destin = new Long[source.length];
for (int i = 0; i < source.length; i++) {
destin[i] = source[i];
}
return destin;
}
/**
* convert Long array to long array
*
* @param source
* @return
*/
public static long[] transformLongArray(Long[] source) {
long[] destin = new long[source.length];
for (int i = 0; i < source.length; i++) {
destin[i] = source[i];
}
return destin;
}
/**
* convert int array to Integer array
*
* @param source
* @return
*/
public static Integer[] transformIntArray(int[] source) {
Integer[] destin = new Integer[source.length];
for (int i = 0; i < source.length; i++) {
destin[i] = source[i];
}
return destin;
}
/**
* convert Integer array to int array
*
* @param source
* @return
*/
public static int[] transformIntArray(Integer[] source) {
int[] destin = new int[source.length];
for (int i = 0; i < source.length; i++) {
destin[i] = source[i];
}
return destin;
}
/**
* compare two object
*
- if v1 > v2, return 1
- if v1 = v2, return 0
- if v1 < v2, return -1
* About result
*
*
*
*
*
- if v1 is null, v2 is null, then return 0
- if v1 is null, v2 is not null, then return -1
- if v1 is not null, v2 is null, then return 1
- return v1.{@link Comparable#compareTo(Object)}
* About rule
*
*
*
*
*
*
* @param v1
* @param v2
* @return
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public static
return v1 == null ? (v2 == null ? 0 : -1) : (v2 == null ? 1 : ((Comparable)v1).compareTo(v2));
}
}
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SystemUtils
系统信息工具类，可用于得到线程池合适的大小，如：
getDefaultThreadPoolSize() 得到跟系统配置相符的线程池大小
public class SystemUtils {
/** recommend default thread pool size according to system available processors, {@link #getDefaultThreadPoolSize()} **/
public static final int DEFAULT_THREAD_POOL_SIZE = getDefaultThreadPoolSize();
private SystemUtils() {
throw new AssertionError();
}
/**
* get recommend default thread pool size
*
* @return if 2 * availableProcessors + 1 less than 8, return it, else return 8;
* @see {@link #getDefaultThreadPoolSize(int)} max is 8
*/
public static int getDefaultThreadPoolSize() {
return getDefaultThreadPoolSize(8);
}
/**
* get recommend default thread pool size
*
* @param max
* @return if 2 * availableProcessors + 1 less than max, return it, else return max;
*/
public static int getDefaultThreadPoolSize(int max) {
int availableProcessors = 2 * Runtime.getRuntime().availableProcessors() + 1;
return availableProcessors > max ? max : availableProcessors;
}
}
原文：https://blog.csdn.net/King1425/article/details/53043596
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