import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.*;
public class ArrayListF{
public static void main(String[] args) throws Exception{
// 创建ArrayList
ArrayList<String> list = new ArrayList<String>(10);
// 向ArrayList中添加新的元素
list.add("This");
list.add("is");
list.add("my");
list.add("site");
// ArrayList的遍历
for (Iterator iter = list.iterator(); iter.hasNext();) {
System.out.println("next is: " + iter.next());
}
// 获取当前ArrayList的大小
// size() - number of items
System.out.println("size of list = " + list.size());
// 获取当前ArrayList的容量
// capacity() - number of items it can hold
Field arrayField = ArrayList.class.getDeclaredField("elementData");
arrayField.setAccessible(true);
Object[] internalArray = (Object[])arrayField.get(list);
System.out.println("capacity of list = " + internalArray.length);
// 判断ArrayList数组是否为空
// is_empty()
System.out.println(list.isEmpty());
// 根据索引,获取某个元素
int index = 3;
System.out.println("the " + index + " element is " + list.get(index));
// 在某个位置插入某个元素
index = 3;
list.add(index, "the insert one");
for (Iterator iter = list.iterator(); iter.hasNext();) {
System.out.println("next is: " + iter.next());
}
// 将某个位置替换为某个元素
list.set(index, "set another one");
for (Iterator iter = list.iterator(); iter.hasNext();) {
System.out.println("next is: " + iter.next());
}
// 删除某个元素
list.remove("set another one");
// 判断是否存在某个元素
System.out.println(list.contains("set another one"));
System.out.println(list.contains("This"));
// 清空ArrayList
list.clear();
// 判断ArrayList是否是空的
System.out.println(list.isEmpty());
}
}
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