例1:
import java.util.*;
public class Main {
public static void main(String[] args) {
//创建collection集合
Collection collection = new ArrayList();
//为集合添加数据
collection.add("苹果");
collection.add("西瓜");
collection.add("橘子");
System.out.println(collection);
System.out.println("--------------");
//使用增强for遍历集合
for (Object object:collection) {
System.out.println(object);
}
System.out.println("*******************");
//使用iterator遍历集合
Iterator iterator=collection.iterator();
while (iterator.hasNext()){
Object a = iterator.next();
System.out.println(a);
}
//输出元素的个数
System.out.println(collection.size());
//判断集合是否包括苹果
System.out.println(collection.contains("苹果"));
//清空集合
collection.clear();
System.out.println(collection.size());
//判断集合是否为空
System.out.println(collection.isEmpty());
}
}
输出结果:
例2
import java.util.*;
public class Main {
public static void main(String[] args) {
//创建list集合
List list = new ArrayList();
//为集合添加元素
list.add("苹果");
list.add("安卓");
list.add(0,"华为");
System.out.println("元素个数:"+list);
//删除元素
list.remove(0);
System.out.println(list);
//遍历集合1
for(int i=0;i<list.size();i++){
System.out.println(list.get(i));
}
System.out.println("**********");
//遍历集合2
for (Object object:list){
System.out.println(object);
}
System.out.println("------------");
//遍历集合3
Iterator iterator = list.iterator();
while (iterator.hasNext()){
System.out.println(iterator.next());
}
System.out.println("+++++++++++++++");
//遍历集合4
ListIterator listIterator = list.listIterator();
while (listIterator.hasNext()){
System.out.println(listIterator.nextIndex()+":"+listIterator.next());
}
System.out.println("+++++++++++++++");
//逆序遍历集合
while (listIterator.hasPrevious()){
System.out.println(listIterator.previousIndex()+":"+listIterator.previous());
}
}
}
输出结果:
例:3
import java.util.*;
public class Main {
public static void main(String[] args) {
//创建list集合
List list = new ArrayList();
//为集合添加元素
list.add(20);
list.add(30);
list.add(40);
list.add(50);
list.add(60);
//删除集合元素的两种方式
System.out.println(list);
list.remove(0);
System.out.println(list);
list.remove(new Integer(40));
System.out.println(list);
}
}
输出结果: