使用JDBC語句執行查詢時出現NullPointerException

Question

我試圖使用通過MySQL連接到存儲在localhost上的數據庫，並且試圖插入一條新語句，但是卻遇到了一個我從未見過的怪異錯誤。 我不確定我的插入語句是否錯誤或任何代碼本身是否錯誤。

我得到的錯誤是

Exception in thread "main" java.lang.NullPointerException
    at DatabaseConnect.main(DatabaseConnect.java:24)
Java Result: 1

//

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class DatabaseConnect {

    public static void main(String[] args) {
        Connection connection = null;
        Statement statement = null;

            //start JDBC
            try {
            //Register JDBC driver
            System.out.println("Connecting to Database...");
            Class.forName("com.mysql.jdbc.Driver"); //connect using JDBC driver 
            System.out.println("Connection to driver Successful");
            System.out.println("Connecting to Database");
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/courseproject", "root", "root"); //connection to database
            System.out.println("Connection to Database successful");
            System.out.println("execute insert statement");
            statement.execute("INSERT INTO courseproject.agent (AGT_ID, AGT_LNAME, AGT_FNAME, AGT_STREET, ADD_ZIP, AGT_PHONE, AGT_EMAIL, OFF_CODE) VALUES ('6', 'firstname', 'lastname', 'street address', '34398', '348374', 'sfhf@aol.com', '35464') ");
        } catch(ClassNotFoundException error){
            System.out.println("Error: " + error.getMessage());

        }catch(SQLException error){
            System.out.println("Error: " + error.getMessage());
        }




    }

}

Answer 1

語句未初始化。 您應該創建一個語句：

statement = connection.createStatement()

還請記住，完成后必須關閉語句並連接到數據庫。