How to convert Integer to int?

JavaInteger

Java 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.

Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
Questionuser405398View Question on Stackoverflow
Solution 1 - Javauser85421View Answer on Stackoverflow
Solution 2 - JavaColinDView Answer on Stackoverflow
Solution 3 - JavaspbfoxView Answer on Stackoverflow
Solution 4 - JavaParth mehtaView Answer on Stackoverflow
Solution 5 - JavaJim ToughView Answer on Stackoverflow