//介紹ArralList順序表中的常用方法
import java.util.ArrayList;
public class ArrayListTest1
{
public static void main(String[] args)
{ //ArrayList中的add方法，返回的是boolean類型。
ArrayList arrayList = new ArrayList();
arrayList.add("hello");
arrayList.add("world");
arrayList.add("world");
arrayList.add("welcome");
//get方法返回的是一個object對象
String s1 = (String)arrayList.get(0);
String s2 = (String)arrayList.get(1);
String s3 = (String)arrayList.get(2);
String s4 = (String)arrayList.get(3);
System.out.println(s1);
System.out.println(s2);
System.out.println(s3);
System.out.println(s4);
System.out.println("------------");
for(int i = 0; i < arrayList.size(); i++)
{
System.out.println(arrayList.get(i));
}
//clear清除集合中的所有對象
//arrayList.clear();
//判斷集合是否爲空
//System.out.println(arrayList.isEmpty());
//remove移除指定索引或內容的對象
arrayList.remove(0);
arrayList.remove("welcome");
System.out.println("------------");
//size方法相當於數組的length，返回集合的長度
for(int i = 0; i < arrayList.size(); i++)
{
System.out.println(arrayList.get(i));
}
System.out.println("--------------");
arrayList.add("aaa");
arrayList.add("bbb");
//indexOf返回指定內容的首次索引號
System.out.println(arrayList.indexOf("world"));
}
}
//ArrayList中不能添加原生數據類型，必須封裝後纔行
import java.util.ArrayList;
public class ArrayListTest2
{
public static void main(String[] args)
{
ArrayList list = new ArrayList();
list.add("hello");
list.add(new Integer(2));
String str = (String)list.get(0);
Integer in = (Integer)list.get(1);
System.out.println(str);
System.out.println(in.intValue());
}
}
import java.util.ArrayList;
public class ArrayListTest3
{
public static void main(String[] args)
{
ArrayList list = new ArrayList();
list.add(new Integer(3));
list.add(new Integer(4));
list.add(new Integer(5));
list.add(new Integer(6));
int sum = 0;
for(int i = 0; i < list.size(); i++)
{
int value = ((Integer)list.get(i)).intValue();
sum += value;
}
System.out.println(sum);
}
}
//不能將Object[]轉換爲Integer[]
import java.util.ArrayList;
public class ArrayListTest4
{
public static void main(String[] args)
{
ArrayList list = new ArrayList();
list.add(new Integer(1));
list.add(new Integer(2));
list.add(new Integer(3));
list.add(new Integer(4));
list.add(new Integer(5));
list.add(new Integer(6));
/*
* 不能將Object[]轉換爲Integer[]
*/
//如果這樣Integer[] in = (Integer)list.toArray();,這是錯誤的方式
Object[] in = list.toArray();
for(int i = 0; i < in.length; i++)
{
System.out.println(((Integer)in[i]).intValue());
}
}
}
//ArrayList默認返回集合中的對象內容，以中括號包住，以逗號分隔
public class ArrayListTest5
{
public static void main(String[] args)
{
ArrayList list = new ArrayList();
list.add(new Point(2, 3));
list.add(new Point(2, 2));
list.add(new Point(4, 4));
for(int i = 0; i < list.size(); i++)
{
System.out.println(list.get(i));
}
System.out.println(list);
}
}
class Point
{
int x;
int y;
/**
*
* @param x coordinate of x
* @param y coordinate of y
*/
public Point(int x, int y)
{
this.x = x;
this.y = y;
}
/**
* @return return coordinate of axis of x and y
*/
public String toString()
{
return "x=" + this.x + ", y=" + this.y;
}
}