Adding Another Collection with the addAll() method: public boolean addAll(Collection c) : 哈希集 « 集合 « Java 教程

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Java 教程 » 集合 » 哈希集

9. 18. 5. Adding Another Collection with the addAll() method: public boolean addAll(Collection c)

Each element in the collection passed in will be added to the set via the equivalent of calling the add() method on each element.

If the underlying set changes, true is returned.

If no elements are added, false is returned.


import java.util.Arrays;

import java.util.HashSet;

import java.util.Set;



public class MainClass {



  public static void main(String[] a) {

    String elements[] = { "A", "B", "C", "D", "E" };

    Set set = new HashSet(Arrays.asList(elements));



    elements = new String[] { "E", "F" };



    set.addAll(Arrays.asList(elements));



    System.out.println(set);

  }

}

[D, A, F, C, B, E]

9. 18. 哈希集
	9. 18. 1.	集和HashSet
	9. 18. 2.	创建HashSet
	9. 18. 3.	An easy way to initialize a set without manually adding each element
	9. 18. 4.	添加内容：添加方法
	9. 18. 5.	Adding Another Collection with the addAll() method: public boolean addAll(Collection c)
	9. 18. 6.	移除所有内容
	9. 18. 7.	Removing Single Elements: public boolean remove(Object element)
	9. 18. 8.	Removing Another Collection: public boolean removeAll(Collection c)
	9. 18. 9.	Retaining Another Collection: public boolean retainAll(Collection c)
	9. 18. 10.	Fetching Elements: to work with all of the elements of the set
	9. 18. 11.	Checking for Existence: the contains() method reports if a specific element is within the set
	9. 18. 12.	the containsAll() method checks if a set contains another whole collection
	9. 18. 13.	To find out how many elements are in a set, use the size() method
	9. 18. 14.	Checking for no elements in the set: use the isEmpty() method instead
	9. 18. 15.	复制和克隆集
	9. 18. 16.	HashSet实现空串行接口
	9. 18. 17.	Converting elements in a set to Array: public Object[] toArray()
	9. 18. 18.	public Object[] toArray(Object[] a)
	9. 18. 19.	The HashSet class defines equality through its equals() method: public boolean equals(Object o)
	9. 18. 20.	查找哈希集的最大元素
	9. 18. 21.	寻找最低元素HashSet
	9. 18. 22.	计数枚举HashSet
	9. 18. 23.	得到同步集HashSet
	9. 18. 24.	检查在HashSet是否存在某一特定因素
	9. 18. 25.	复制所有内容HashSet到对象数组
	9. 18. 26.	获取HashSet尺寸
	9. 18. 27.	通过HashSet元素迭代
	9. 18. 28.	移除所有元素HashSet
	9. 18. 29.	删除指定的元素HashSet
	9. 18. 30.	整型值设置
	9. 18. 31.	Listing the Elements of a Collection(iterate over the elements of set or list)
	9. 18. 32.	制作只读集
	9. 18. 33.	转换数组设置
	9. 18. 34.	Create unique lists of items?

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