1、java中ArrayList使用remove注意事项java中ArrayList使用remove注意事项 /在remove一条信息时，ArrayList的大小已经改变（即list.size()已经改变）；在i大于等于list.size()时，循环跳出，后便的ArrayList不能再执行；所以必须在remove的同时，执行i-，即i=i-1；现在才能遍历所有List中的信息。也不能在用Iterator遍历时使用remove,会抛异常。public class TrickyAL publicstatic LinkedList<User> llu=newLinkedList<Use
2、r>(); publicstatic HashMap<String,User> hmu=newHashMap<String,User>(); publicstatic ArrayList<User> ulist=newArrayList<User>(Arrays.asList (newUser new User(2,Eric), new User(3,Eric), new User(1,Aaron), new User(4,Eric) ); static llu.add(new User(1,Aaron); llu.add(new User
3、(2,Eric); llu.add(new User(3,Tom); hmu.put(1,new User(3,Tom); hmu.put(2,new User(2,Eric); hmu.put(3,new User(1,Leo); hmu.put(3,new User(4,Scott); publicstatic voiddeleteUser(ArrayList<User>urlist,String auser) Iterator itr=urlist.iterator(); int c=urlist.size(); for(int i=0;i<c;i+) if(auser
4、.equals(urlist.get(i).name) urlist.remove(i); i-; c-; public static voiddeleteUser(LinkedList<User>urlist,String auser) Iterator itr=urlist.iterator(); int c=urlist.size(); for(int i=0;i<c;i+) if(auser.equals(urlist.get(i).name) urlist.remove(i); i-; c-; public static voiddeleteUser(HashMap
5、<String,User>urlist,String auser) intc=urlist.size(); Iteratorhmi=urlist.entrySet().iterator(); Stringks=; for(Stringsk : urlist.keySet() if(auser.equals(urlist.get(sk).name) System.out.println(auser); ks=sk; break; urlist.remove(ks); publicstatic void main(String args) / TODO Auto-generated m
6、ethod stub /ArrayList mul=(ArrayList)ulist; System.out.println(ulist); /deleteUser(ulist,Eric); /Arrays.sort(ulist.toArray(); System.out.println(ulist); System.out.println(2->+llu); Collections.reverse(llu); deleteUser(llu,Eric); System.out.println(llu); System.out.println(3->+hmu); deleteUser
7、(hmu,Eric); System.out.println(hmu); Collections.copy(ulist,llu ); System.out.println(ulist); System.out.println(llu); publicstatic class User public int id; public String name; public User(int id,String name) this.id=id; this.name=name; public String toString() returnString.valueOf(this.id)+,+this.name;
