class MyHashMap {

    int [] hashmap ; 

    /** Initialize your data structure here. */
    public MyHashMap() {
        hashmap = new int [1000001] ;
        Arrays.fill(hashmap, -1);
    }

    /** value will always be non-negative. */
    public void put(int key, int value) {
        hashmap[key] = value;
    }

    /** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
    public int get(int key) {
        return hashmap[key];
    }

    /** Removes the mapping of the specified value key if this map contains a mapping for the key */
    public void remove(int key) {
        hashmap[key] = -1;
    }
}
/**
 * Your MyHashMap object will be instantiated and called as such:
 * MyHashMap obj = new MyHashMap();
 * obj.put(key,value);
 * int param_2 = obj.get(key);
 * obj.remove(key);
 */

boolean[] a1 = new boolean[5];
Arrays.fill( a1,true );
结果 a1[] = {true,true,true,true,true};
用法2：接受4个参数
例如：
String[] a9 = new String[6];
Arrays.fill(a9, "Hello");
Arrays.fill(a9, 3, 5,"World");
结果是 a9[] = {Hello,Hello,Hello,World,World,Hello};