Collection<String> coll = new ArrayList<>(); System.out.println(coll);
输出:java
[]
boolean b1 = coll.add("jack"); System.out.println(b1); coll.add("Mack"); coll.add("John"); coll.add("Tom"); System.out.println(coll);
输出web
true [jack, Mack, John, Tom]
System.out.println(coll); System.out.println(coll.remove("Mack")); //删除的对象存在,返回true System.out.println(coll); System.out.println(coll.remove("Jarry")); //删除的对象不存在,返回false System.out.println(coll);
输出:数组
[jack, Mack, John, Tom] true [jack, John, Tom] false [jack, John, Tom]
System.out.println(coll); System.out.println(coll.contains("jack")); //集合中包含jack,返回true System.out.println(coll.contains("Jerry")); //集合中不包含Jerry,返回false
输出:svg
[jack, John, Tom] true false