移除数组中重复元素
Use hashset to remove duplicated elements
public HashSet(Collection<? extends E> c) {
map = new HashMap<E,Object>(Math.max((int) (c.size()/.75f) + 1, 16));
addAll(c);
}
public static void main(String[] args) {
String[] str = new String[10];
//Initializing the array with duplicate elements
for(int i=0;i<10;i++){
str[i] = "str";
}
//Arrays.asList, convert array to collection
//remove duplicates here
Set s = new HashSet(Arrays.asList(str));
//Collection.toArray, convert collection to array.
String[] y = (String[]) s.toArray(new String[0]);
System.out.println(s.toArray());
System.out.println(y);
}
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<T> List<T> asList(T... a)
(<String> List<String> java.util.Arrays.asList(String... a))
Returns a fixed-size list backed by the specified array. (Changes to the returned list "write through" to the array.) This method acts as bridge between array-based and collection-based APIs, in combination with Collection.toArray. The returned list is serializable and implements RandomAccess.
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* @param a the array into which the elements of this set are to be
* stored, if it is big enough; otherwise, a new array of the same
* runtime type is allocated for this purpose. * @return an array containing all the elements in this set
* @throws ArrayStoreException if the runtime type of the specified array
* is not a supertype of the runtime type of every element in this
* set
* @throws NullPointerException if the specified array is null
*/
<T> T[] toArray(T[] a);
----------
public static void main(String[] args) {
String[] str = new String[10];
//Initializing the array with duplicate elements
for(int i=0;i<10;i++){
str[i] = "str";
}
// List a = Arrays.asList(str);
// a.toArray();
//remove duplicates here
Set<String> s = new HashSet<String>(Arrays.asList(str));
//s = new HashSet<String>();
String[] x = new String[s.size()];
String[] y = s.toArray(x);
System.out.println(x==y);//true, both of x,y are "str"
System.out.println(s.toArray());
System.out.println(y);
}
