Java中List集合去除重复数据的方法
2017-01-20 16:42
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1. 循环list中的所有元素然后删除重复
[java]
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public static List 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);
}
}
}
return list;
}
2. 通过HashSet踢除重复元素
[java]
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public static List removeDuplicate(List list) {
HashSet h = new HashSet(list);
list.clear();
list.addAll(h);
return list;
}
3. 删除ArrayList中重复元素,保持顺序
[java]
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// 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);
}
4.把list里的对象遍历一遍,用list.contain(),如果不存在就放入到另外一个list集合中
[java]
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public static List removeDuplicate(List list){
List listTemp = new ArrayList();
for(int i=0;i<list.size();i++){
if(!listTemp.contains(list.get(i))){
listTemp.add(list.get(i));
}
}
return listTemp;
}
[java]
view plain
copy
public static List 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);
}
}
}
return list;
}
2. 通过HashSet踢除重复元素
[java]
view plain
copy
public static List removeDuplicate(List list) {
HashSet h = new HashSet(list);
list.clear();
list.addAll(h);
return list;
}
3. 删除ArrayList中重复元素,保持顺序
[java]
view plain
copy
// 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);
}
4.把list里的对象遍历一遍,用list.contain(),如果不存在就放入到另外一个list集合中
[java]
view plain
copy
public static List removeDuplicate(List list){
List listTemp = new ArrayList();
for(int i=0;i<list.size();i++){
if(!listTemp.contains(list.get(i))){
listTemp.add(list.get(i));
}
}
return listTemp;
}
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