小编use*_*636的帖子

我对如何防止 SQL 注入感到困惑，我在网上查看过。我是使用存储过程，还是创建变量，我完全迷失了。

 Try\n connection.Open()\n \xe2\x80\x99we got here so our connection to the db is sound\n chosen = cboBooks.SelectedIndex\n id = customerList(cboCustomers.SelectedIndex)\n isbn = isbnList(cboBooks.SelectedIndex)\n If number <= qty Then\n     Dim sql As String\n     sql = "INSERT INTO purchase(customer_id, ISBN, store_id, quantity)\n                        VALUES(" & id & ", " & isbn & ", 1, " & number & ");"\n     Dim cmd As New SqlCommand(sql, connection)\n     Dim rows As Integer\n     rows = cmd.ExecuteNonQuery()\n     If rows >= 1 Then\n     \xe2\x80\x99now update the …

尝试将项目添加到列表并打印它们,它编译,但我得到一个运行时错误,其中堆栈溢出错误.这是错误打印出来的:

Exception in thread "main" java.lang.StackOverflowError
at List.<init>(List.java:5)
at List.<init>(List.java:9)
at List.<init>(List.java:9) <----- this line is repeated quite a few times 

这是我的代码,包含添加和打印列表的方法.

public class List {

private AthleteNode front;

public List(){
front = null;
}

public List athletes = new List();

//add athlete to the end of the list 
public void add(Athlete a){

AthleteNode node = new AthleteNode (a);
AthleteNode current; //temp node to iterate over the list

if(front == null)
    front = node;//adds the first element

else{
    current = …