我一直得到java.lang.NumberFormatException：对于输入字符串：“”

Question

我试图返回4个值，其中两个是字符串。但我继续得到NumberFormatException。这是错误来自的部分。

try{
    Class.forName("org.sqlite.JDBC");
    Connection connection = DriverManager.getConnection("jdbc:sqlite:C:\\Users\\Butch\\Desktop\\Database\\StudentBase.sqlite");
    PreparedStatement statement=connection.prepareStatement(("select FirstName+LastName,GradeLevel,ReadingLevel from Student where FirstName=? AND LastName=? AND GradeLevel=? AND ReadingLevel=?"));
    statement.setString(1,textField.getText());
    statement.setInt(2,Integer.parseInt(textField_3.getText()));
    statement.setInt(3,Integer.parseInt(textField_2.getText()));
    ResultSet resultset=statement.executeQuery();
    while(resultset.next())
    {
    textField.setText(resultset.getString(1));
    textField_3. setText(Double.toString(resultset.getInt(2)));
    textField_2. setText(Double.toString(resultset.getInt(3)));
    }

}

}
catch(Exception e){JOptionPane.showMessageDialog(null, e);
    }

有没有办法重写它？

Answer 1

尝试：改变这个：

statement.setInt(2,Integer.parseInt(textField_3.getText()));
statement.setInt(3,Integer.parseInt(textField_2.getText()));

对此：

statement.setInt(2,Integer.parseInt("0"+textField_3.getText()));
statement.setInt(3,Integer.parseInt("0"+textField_2.getText()));