方法一:循环元素删除
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
for ( int i = 0 ; i < list.size() - 1 ; i ++ ) {
for ( int j = list.size() - 1 ; j > i; j -- ) {
if (list.get(j).equals(list.get(i))) {
list.remove(j);
}
}
}
System.out.println(list);
}
方法二:通过HashSet剔除
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
HashSet h = new HashSet(list);
list.clear();
list.addAll(h);
System.out.println(list);
}
方法三: 删除ArrayList中重复元素,保持顺序
// 删除ArrayList中重复元素,保持顺序
public static void removeDuplicateWithOrder(List list) {
Set set = new HashSet();
List newList = new ArrayList();
for (Iterator iter = list.iterator(); iter.hasNext();) {
Object element = iter.next();
if (set.add(element))
newList.add(element);
}
list.clear();
list.addAll(newList);
System.out.println( " remove duplicate " + list);
} 参考与:http://xinqiqi123.iteye.com/blog/1148984
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
for ( int i = 0 ; i < list.size() - 1 ; i ++ ) {
for ( int j = list.size() - 1 ; j > i; j -- ) {
if (list.get(j).equals(list.get(i))) {
list.remove(j);
}
}
}
System.out.println(list);
}
方法二:通过HashSet剔除
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
HashSet h = new HashSet(list);
list.clear();
list.addAll(h);
System.out.println(list);
}
方法三: 删除ArrayList中重复元素,保持顺序
// 删除ArrayList中重复元素,保持顺序
public static void removeDuplicateWithOrder(List list) {
Set set = new HashSet();
List newList = new ArrayList();
for (Iterator iter = list.iterator(); iter.hasNext();) {
Object element = iter.next();
if (set.add(element))
newList.add(element);
}
list.clear();
list.addAll(newList);
System.out.println( " remove duplicate " + list);
} 参考与:http://xinqiqi123.iteye.com/blog/1148984
List<String> list = new ArrayList<String>();
for(int i=0; i<li.size(); i++){
String str = li.get(i); //获取传入集合对象的每一个元素
if(!list.contains(str)){ //查看新集合中是否有指定的元素,如果没有则加入
list.add(str);
}
}
return list; //返回集合
} public class Test{
public static void main(String[] args){
ArrayList<String> arr = new ArrayList<String>();
arr.add("aaa");
arr.add("bbb");
arr.add("aaa");
arr.add("ccc");
arr = getNewList(arr); //方法去重
System.out.println(arr);
}
}
if(Collections.frequency(reslut, s) < 1) result.add(s);
}
if(Collections.frequency(reslut, s) < 1) result.add(s);
}
list.add("AAAA");
list.add("AAAA");
list.add("BBBB");
list.add("CCCC");
list.add("DDDD");
list.add("AAAA");
list.add("BBBB");
List list1 = new ArrayList();
for(int z=0;z<list.size();z++)
{
if(!list1.contains(list.get(z))){
list1.add(list.get(z));
}
}
{
HashSet h=new HashSet(arlList);
arlList.clear();
arlList.addAll(h);
List list=new ArrayList();
list=arlList;
return list;
}
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;public class Test {
public static void main(String[] args) {
List list = new ArrayList();
list.add("A");
list.add("B");
list.add("C");
list.add("A");
list.add("A");
System.out.println(list.size());
Set s = new HashSet();
for(int i=0;i<list.size();i++){
s.add(list.get(i));
}
System.out.println(s.size());
for (Iterator iterator = s.iterator(); iterator.hasNext();) {
Object object = (Object) iterator.next();
System.out.print(object);
}
}
}
public boolean equals(Object obj)
方法。
public static void main(String[] args) {
List<Integer> list = new ArrayList<Integer>();
list.add(1);
list.add(1);
list.add(2);
list = new ArrayList<Integer>(new HashSet<Integer>(list));
}
仅仅一行代码就搞掂了~