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源码版本

commons-lang3-3.1.jar

源码介绍

功能介绍

Operations on arrays, primitive arrays (like {@code int[]}) andprimitive wrapper arrays (like {@code Integer[]}).This class tries to handle {@code null} input gracefully.An exception will not be thrown for a {@code null}array input. However, an Object array that contains a {@code null}element may throw an exception. Each method documents its behaviour.

To map

public static Map
   
     toMap(final Object[] array) {
       if (array == null) {
           return null;    }    // 定义map的初始容量，乘以1.5考虑的是加载因子    final Map
    
      map = new HashMap<>((int) (array.length * 1.5));    for (int i = 0; i < array.length; i++) {
           final Object object = array[i];        if (object instanceof Map.Entry
     ) {
               final Map.Entry
      entry = (Map.Entry
     ) object;            map.put(entry.getKey(), entry.getValue());        } else if (object instanceof Object[]) {
               final Object[] entry = (Object[]) object;            if (entry.length < 2) {
                   throw new IllegalArgumentException("Array element " + i + ", '"                    + object                    + "', has a length less than 2");            }            map.put(entry[0], entry[1]);        } else {
               throw new IllegalArgumentException("Array element " + i + ", '"                    + object                    + "', is neither of type Map.Entry nor an Array");        }    }    return map;}
    
   

Generic array

// JDK5 可变参数（Varargs）public static 
   
     T[] toArray(final T... items) {
     return items;}
   

isEmpty

public static boolean isEmpty(final Object[] array) {
       return getLength(array) == 0;}public static int getLength(final Object array) {
       if (array == null) {
           return 0;    }    return Array.getLength(array);}

Reverse

public static void reverse(final Object[] array) {
      if (array == null) {
          return;   }   reverse(array, 0, array.length);}public static void reverse(final long[] array) {
      if (array == null) {
          return;   }   reverse(array, 0, array.length);}

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