Java 8, Luna, Subclipse

Yep, going to try Java8 already. I installed the JDK a couple of weeks ago, since I was updating Java7 anyway, and found that it would indeed appear as a JRE in Eclipse; but didn't take it further.

But now I am. Downloaded Eclipse Luna, 4.4M7. Tried to changed Java compiler settings to output version 7 class format, but allow Java 8 source. I had somehow got the idea that that should be allowed. And why would you output legacy 7 code as format 8, anyway? But it isn't allowed. So 8 in, 8 out, then. Seems to work fine.

But with J8 output, I had to install Java8 on a target server; so here's how to do that. You probably don't have to use all of it.

nano /etc/hosts # because sudo complained about not resolving hostname
sudo apt-get install software-properties-common # because 'add-apt-repository' wasn't there

sudo add-apt-repository ppa:webupd8team/java

sudo apt-get update

sudo apt-get install oracle-java8-installer

I also installed Subclipse 1.6. The file/folder status markers were added, but it wouldn't synchronize, "Unable to load default SVN Client", so I tried installing the SvnKit module too. I have the habit to try to install as little as possible, so one thing at a time, although a few restarts are needed. Still no go.

And then I saw the "SVNKit Client Adapter (Not required)", which makes perfect sense; so I installed that, and now these rather old Subclipse modules work inside the latest Eclipse.

So, done and done. Could be easier, but still comparably easy. Java 8 has arrived in my toolchain; to stay, I think. I read that it's very backwards-compatible, source-code wise.

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Oh, right. Got an OOM during build, so the memory allotment param in eclipse.ini (inside the app) had to be edited too. Changed to "-Xmx1500m" from "-Xmx512m".

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Ah, trying a lambda expression as first thing, of course. Error: "Lambda expressions are allowed only at source level 1.8 or above". That's nice, it knows about Java8 even at Java7 source setting. There's even a quick tip: "Change project compliance and JRE to 1.8". Well, yes to that, thank you; wow much thoughtful.

And isn't that just cute:

public static void main(String...args) {

   Sam sam = (a, b) -> a + b;

}

interface Sam {

  int bla(int a, int b);

}

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Trying out what I thought would be the most important feature of Java8, the default (aka defender) methods. Of course, it turns out they don't work as I'd thought.

public class Java8Demo { public static void main(String...args) { Sam sam = (a, b) -> a + b; // SamDefend sd = (a, b) -> a + b; // The target type of this expression must be a functional interface } interface Sam extends SamDefend { int bla(int a, int b); } interface SamDefend { default int bla(int a, int b) { return a + b; } }// Sam sam = new Sam() { // The type new Java8Demo.Sam(){} must implement the inherited abstract method Java8Demo.Sam.bla(int, int)//// @Override//// public int bla(int a, int b) {//// // TODO Auto-generated method stub//// return 0;//// }// };}

Oh #. Blogger/blogspot sucks, especially for blogging software development stuff...why can't I just paste code with formatting intact?

public class Java8Demo {
 public static void main(String...args) {
  Sam sam = (a, b) -> a + b;
  // SamDefend sd = (a, b) -> a + b; // The target type of this expression must be a functional interface
 }
 interface Sam extends SamDefend {
  int bla(int a, int b);
 }
 interface SamDefend {
  default int bla(int a, int b) {
   return a + b;
  }
 }
// Sam sam = new Sam() { // The type new Java8Demo.Sam(){} must implement the inherited abstract method Java8Demo.Sam.bla(int, int)
////  @Override
////  public int bla(int a, int b) {
////   // TODO Auto-generated method stub
////   return 0;
////  }
// };
}

Meh. That's as close as it gets.