arraylist

public class ArrayListTest {

public static void main(String[] args) {
ArrayList<String> arrayList = new ArrayList<String>();
//ArrayList arrayList = new ArrayList();
//共有的方法
arrayList.add("1");
arrayList.add("2");
arrayList.add("4");
arrayList.add("5");
arrayList.add(2, "3");
System.out.println(arrayList);//1,2,3,4,5
int lenght = arrayList.size();//5
System.out.println(lenght);//5
String two = arrayList.get(2);//强制转换 3
System.out.println(two); //3
System.out.println(arrayList.contains("6"));//false
arrayList.remove("5");//1,2,3,4
System.out.println(arrayList.size());//4
arrayList.remove(0);//2,3,4
System.out.println(arrayList.contains("1"));//false
System.out.println(arrayList.indexOf("2"));//0
System.out.println(arrayList.lastIndexOf("4"));//2
arrayList.set(0, "0");//0,3,4
System.out.println(arrayList.contains("2"));//false
System.out.println(arrayList.indexOf("0"));//0

//存对象数据
ArrayList<News> arrayList2 = new ArrayList<News>();
News news0 = new News("1", "12");
News news1 = new News("2", "23");
News news2 = new News("3", "34");
News news3 = new News("4", "45");
arrayList2.add(news0);
arrayList2.add(news1);
arrayList2.add(news2);
arrayList2.add(news3);
}

}