java - 比较数组并删除重复项

Question

我想比较两个不同维度的数组，然后消除重复项并将结果放入名为 tmp 的数组中

这是代码

ArrayList<String> list = new ArrayList<String>();
HashSet<String> tmp = new HashSet<String>();

try 
{
    String query1="SELECT ID FROM Apps;";
        ResultSet rs = con.createStatement().executeQuery(query1);
        while(rs.next())
        {
            list.add(rs.getString("ID"));
            tmp.add(rs.getString("ID"));
        }

        for(int i=0;i < check.size();i++)//ciclo  le checkbox selezionate
        {
                check.get(i);
                String query="UPDATE Apps SET Authorized='1' WHERE ID=" +check.get(i);//vado ad eseguire la query di update
                pr=con.prepareStatement(query);
                pr.executeUpdate();
                tmp.add(check.get(i).toString());
        }

        System.out.println(tmp);

两个数组的内容为:

check -> [1, 2]
list -> [1, 2, 3, 4, 5]

我想要的结果是tmp -> [3,4,5]

但是控制台显示tmp -> [1,2,3,4,5]

Answer 1

您可以像这样删除重复项:

    public static void main(String[] args) {

    Set<Integer> tmp = new HashSet<>();
    List<Integer> check = new ArrayList<>();
    check.add(1);
    check.add(2);
    List<Integer> list = new ArrayList<>();
    for(int i = 1; i <= 5; i++){
        list.add(i);
    }

    tmp.addAll(list);
    tmp.removeAll(check);
    System.out.println(tmp);
}