Java Collection使用介绍

Collection 使用

package 集合类;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo2 {
	public static void main(String[] args) {
		Collection collection = new ArrayList();
		Student s1= new Student("1",1);
		Student s2= new Student("2",2);
		Student s3= new Student("3",3);
		collection.add(s1);
		collection.add(s2);
		collection.add(s3);
		System.out.println(collection.toString());
		System.out.println(collection);
		//[Student [name=1, age=1], Student [name=2, age=2], Student [name=3, age=3]]
		//[Student [name=1, age=1], Student [name=2, age=2], Student [name=3, age=3]]
		
		//Student 里面若无重写方法，则打印出地址
//		[集合类.Student@15db9742, 集合类.Student@6d06d69c, 集合类.Student@7852e922]
//		[集合类.Student@15db9742, 集合类.Student@6d06d69c, 集合类.Student@7852e922]
	}

}

package 集合类;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public class CollectionDemo {
	public static void main(String[] args) {
		Collection collection = new ArrayList();
		collection.add("西瓜");
		collection.add("苹果");
		collection.add("橘子");
		System.out.println(collection);
	    for(Object object: collection) {
	    	System.out.print(object+" ");
	    }
		System.out.println();
		Iterator it = collection.iterator();
		
		while(it.hasNext()) {
			//System.out.println(it.next());//都可以
			String s = (String)it.next();
			System.out.println(s);
		}
		
		System.out.println(collection.contains("西瓜"));
		System.out.println(collection.isEmpty());
	}

}

本文地址：https://blog.csdn.net/qinghing25/article/details/110288902