下面的图片是Collection接口的所有方法及解释
下面是证明,为方便查看,将代码拆分开来
Collection<String> coll = new ArrayList<String>();
boolean boo = coll.isEmpty();
System.out.println(boo);
coll.add("aa");
coll.add("ss");
coll.add("dd");
int i1 = coll.size();
System.out.println(i1);
boolean b1= coll.contains("a");
System.out.println(b1);
Object [] arr = coll.toArray();
System.out.println(Arrays.toString(arr));
coll.add("ff");
System.out.println(coll);
coll.remove("ss");
System.out.println(coll);
coll.clear();
System.out.println(coll);
Collection<String> coll1 = new ArrayList<String>();
coll1.add("aa");
boolean b2 = coll.containsAll(coll1);
System.out.println(b2);
coll1.add("qq");
coll1.add("ww");
System.out.println("coll "+coll);
System.out.println("coll1 "+coll1);
coll.addAll(coll1);
System.out.println(coll);
coll.removeAll(coll1);
System.out.println(coll);
coll.retainAll(coll1);
System.out.println(coll);