我只是想在eclipse上運行一個問題Java程序,但得到NullPointerException。我的代碼發佈在下面。請告訴我我做錯了什麼。異常在從數據庫中獲取值時線程main java.lang.NullPointerException
Rect.java
package org.spring.model;
public class Rect {
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Rect(int rectId, String rectName)
{
setId(rectId);
setName(rectName);
}
}
JdbcDaoImplement.java
package org.spring.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.spring.model.Rect;
public class JdbcDaoImplement {
public Rect getRect(int rectId)
{
Connection conn=null;
try
{
Class.forName("oracle.jdbc.OracleDriver");
String jdbcUrl = "jdbc:oracle:thin:@localhost:1521:ORCL";
conn = DriverManager.getConnection(jdbcUrl, "system", "abcd");
PreparedStatement ps=conn.prepareStatement("SELECT * FROM RECTANGLE WHERE id=?");
ps.setInt(1, rectId);
Rect rect=null;
ResultSet rs=ps.executeQuery();
if(rs.next()==true)
{
rect=new Rect(rectId,rs.getString("name"));
}
rs.close();
ps.close();
return rect;
}
catch(Exception e)
{
throw new RuntimeException();
}
finally
{
try {
conn.close();
} catch (SQLException e) {
//e.printStackTrace();
}
}
}
}
最後,JdbcDemo.java
package org.spring;
import org.spring.dao.JdbcDaoImplement;
import org.spring.model.Rect;
public class JdbcDemo {
public static void main(String[] args) {
Rect rect=new JdbcDaoImplement().getRect(1);
System.out.println(rect.getName());
}
}
而且堆棧跟蹤是:
Exception in thread "main" java.lang.NullPointerException
at org.spring.JdbcDemo.main(JdbcDemo.java:10)
如果您要告訴我們一個異常,請給出完整的堆棧跟蹤。 –
好吧,我編輯並重新發布了完整的堆棧跟蹤問題。 – Poles