How to convert Integer to int?
JavaIntegerJava Problem Overview
I am working on a web application in which data will be transfer between client & server side.
I already know that JavaScript int != Java int. Because, Java int cannot be null, right. Now this is the problem I am facing.
I changed my Java int variables into Integer.
public void aouEmployee(Employee employee) throws SQLException, ClassNotFoundException
{
Integer tempID = employee.getId();
String tname = employee.getName();
Integer tage = employee.getAge();
String tdept = employee.getDept();
PreparedStatement pstmt;
Class.forName("com.mysql.jdbc.Driver");
String url ="jdbc:mysql://localhost:3306/general";
java.sql.Connection con = DriverManager.getConnection(url,"root", "1234");
System.out.println("URL: " + url);
System.out.println("Connection: " + con);
pstmt = (PreparedStatement) con.prepareStatement("REPLACE INTO PERSON SET ID=?, NAME=?, AGE=?, DEPT=?");
pstmt.setInt(1, tempID);
pstmt.setString(2, tname);
pstmt.setInt(3, tage);
pstmt.setString(4, tdept);
pstmt.executeUpdate();
}
My problem is here:
pstmt.setInt(1, tempID);
pstmt.setInt(3, tage);
I cant use the Integer variables here. I tried with intgerObject.intValue();
But it makes things more complex. Do we have any other conversion methods or conversion techniques?
Any fix would be better.
Java Solutions
Solution 1 - Java
As already written elsewhere:
- For Java 1.5 and later you don't need to do (almost) anything, it's done by the compiler.
- For Java 1.4 and before, use
Integer.intValue()
to convert from Integer to int.
BUT as you wrote, an Integer
can be null, so it's wise to check that before trying to convert to int
(or risk getting a NullPointerException
).
pstmt.setInt(1, (tempID != null ? tempID : 0)); // Java 1.5 or later
or
pstmt.setInt(1, (tempID != null ? tempID.intValue() : 0)); // any version, no autoboxing
* using a default of zero, could also do nothing, show a warning or ...
I mostly prefer not using autoboxing (second sample line) so it's clear what I want to do.
Solution 2 - Java
Since you say you're using Java 5, you can use setInt
with an Integer
due to autounboxing: pstmt.setInt(1, tempID)
should work just fine. In earlier versions of Java, you would have had to call .intValue()
yourself.
The opposite works as well... assigning an int
to an Integer
will automatically cause the int
to be autoboxed using Integer.valueOf(int)
.
Solution 3 - Java
Java converts Integer to int and back automatically (unless you are still with Java 1.4).
Solution 4 - Java
Another simple way would be:
Integer i = new Integer("10");
if (i != null)
int ip = Integer.parseInt(i.toString());
Solution 5 - Java
Perhaps you have the compiler settings for your IDE set to Java 1.4 mode even if you are using a Java 5 JDK? Otherwise I agree with the other people who already mentioned autoboxing/unboxing.