java.lang.NullPointerException** 错误？

Question

我正在尝试用 Java 将记录添加到 Sql Server。在此函数中，程序给出如下错误:

Connected
1
2
Error java.lang.NullPointerException

这是输出..

函数如下:

public class DB {

    Connection con = null;
    Statement stmt Nnull ;
    component cmp = new Component();

    public long pSave(Component cmp) {
        String i = cmp.getI();
        String s = cmp.getS();
        String a = cmp.getA();
        int t = cmp.getT();
        int c = cmp.getC();

        System.out.println("1");

        try {
            System.out.println("2");
            stmt = con.createStatement();

            System.out.println("3");
            String SQL =
                "INSERT INTO kisi (cl1,cl2,cl3,cl4,cl5) "
                + "VALUES(" + i + "," + s + "," + a + "," + c + "," + t + ")";

            System.out.println("4");
            stmt.executeUpdate(SQL);

            System.out.println("Success");

            return 1;
        } catch(Exception e) {
            System.out.println("Error " + e);
            return 0;
        }
    }

}

Answer 1

Connection con = null;
......
stmt = con.createStatement();
        ^

连接未初始化。您必须连接到数据库才能检索数据。