Sou iniciante em programação e estou tendo o erro Exception in thread “main” java.lang.NullPointerException ao executar o código abaixo.
Poderiam me ajudar?
package minhaaplicacao;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Connection;
import java.sql.*;
import java.lang.NullPointerException;
public class Conexao {
public String status;
public Connection conectar = null;
public java.sql.Connection Conectar(){
conectar = null;
String nomeDriver = "conn.mysql.jdbc.Driver";
try{
Class.forName(nomeDriver);
}
catch
(ClassNotFoundException ex)
{
status = ex.getMessage();
}
String server = "localhost";
String BD = "quiz";
String URL = "JDBC:mysql://" + server + "/" + BD;
String user = "root";
String pwd = "root";
try{
conectar = DriverManager.getConnection(URL,user,pwd);
return conectar;
}
catch (SQLException ex){
status = "erro:\n" + ex.getMessage();
return conectar;
}
}
public boolean Inserir(String valor){
try {
Conectar();
PreparedStatement prep = conectar.prepareStatement("insert into USUARIO values (null,'" + valor + "')");
prep.execute();
return true;
}catch (SQLException ex){
status = ex.getMessage();
System.out.println(status);
return false;
}
}
public void LerDados(){
Conectar();
try{
Statement stm;
stm = conectar.createStatement();
String str = "select * from USUARIO";
ResultSet rs = stm.executeQuery(str);
while(rs.next()){
System.out.println(rs.getString("ID_USUARIO"));
System.out.println(rs.getString("NOME"));
} conectar.close();
} catch (SQLException ex){
System.out.println(ex.getMessage());
}
}
}