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  • 10.18 java

    1.构造函数

    *无参构造函数

    public ArrayList() {
        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
    }

    *一个参数的构造方法,参数为初始的容量

    public ArrayList(int initialCapacity) {
            if (initialCapacity > 0) {
                this.elementData = new Object[initialCapacity];
            } else if (initialCapacity == 0) {
                this.elementData = EMPTY_ELEMENTDATA;
            } else {
                throw new IllegalArgumentException("Illegal Capacity: "+initialCapacity);
            }
        }

    *参数为集合的构造方法

    public ArrayList(Collection<? extends E> c) {
            elementData = c.toArray();
            if ((size = elementData.length) != 0) {   
                if (elementData.getClass() != Object[].class)
                    elementData = Arrays.copyOf(elementData, size, Object[].class);
            } else {
                this.elementData = EMPTY_ELEMENTDATA;
            }
        }

    //ArrayList集合增加元素

    import.java.util.AttayList;
    import.java.util.List;
    piblic class ListDemo {
     public static void main(String[] args) {
      List lis = new ArrayList();
      lis.add("张三");
      lis.add("张三");
      lis.add("李四");
      lis.add("王五");
      System.out.println(lis);
     }
    }

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  • 原文地址:https://www.cnblogs.com/SirNie/p/13542848.html
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