javac (as “java compiler”) is an executable, which could be theoretically even a platform-dependent executable or a script. This is called to compile a .java to a .class. On windows is its name javac.exe, and it is normally somewhere below C:\Program Files*\jdk*\bin. This compiler was developed in java as well. That means, if we start …
It is possible to detect the proxy using the ProxySelector class and assign the system proxy by assigning environment variables with the setProperty method of the System class: System.setProperty(“java.net.useSystemProxies”, “true”); System.out.println(“detecting proxies”); List l = null; try { l = ProxySelector.getDefault().select(new URI(“http://foo/bar”)); } catch (URISyntaxException e) { e.printStackTrace(); } if (l != null) { for …
On Linux, use colon : as separator (as you will do with the classpath option) as in: -Djava.library.path=/opt/hdf-java/build/bin:/opt/opencv-2.4.10/build/lib
Do it like: java -Xms256m -Xmx512m -Djava.awt.headless=true -jar filename.jar
It’s not a programmatic solution but you can run java -verbose:class …. and the JVM will dump out what it’s loading, and from where. [Opened /usr/java/j2sdk1.4.1/jre/lib/rt.jar] [Opened /usr/java/j2sdk1.4.1/jre/lib/sunrsasign.jar] [Opened /usr/java/j2sdk1.4.1/jre/lib/jsse.jar] [Opened /usr/java/j2sdk1.4.1/jre/lib/jce.jar] [Opened /usr/java/j2sdk1.4.1/jre/lib/charsets.jar] [Loaded java.lang.Object from /usr/java/j2sdk1.4.1/jre/lib/rt.jar] [Loaded java.io.Serializable from /usr/java/j2sdk1.4.1/jre/lib/rt.jar] [Loaded java.lang.Comparable from /usr/java/j2sdk1.4.1/jre/lib/rt.jar] [Loaded java.lang.CharSequence from /usr/java/j2sdk1.4.1/jre/lib/rt.jar] [Loaded java.lang.String from /usr/java/j2sdk1.4.1/jre/lib/rt.jar] See …
This question is superficially about performance of code compiled with GHC vs code running on the JVM. But there are a lot of other factors that come into play. People Is there a team working on this, or just you? How familiar/comfortable is that team with these languages? Is this a language you (all) want …
Suggested reading: the JVM spec. You might also want to play with BCEL – there are other libraries around for manipulating bytecode, but that’s probably the best known one.
Update: This answer was originally written in 2014 and is obsolete. Peter ‘s answer is correct in that -Xms is allocated at startup and it will grow up to -Xmx (max heap size) but it’s a little misleading in how he has worded his answer. (Sorry Peter I know you know this stuff cold). Setting …
If I compiled a java file in the newest JDK, would an older JVM be able to run the .class files? That depends on three things: The actual Java versions you are talking about. For instance, a 1.4.0 JVM can run code compiled by a 1.4.2 compiler, but a 1.3.x JVM cannot1. The compilation flags …
You can get the object index with Unsafe. Depending on how the JVM is using the memory (32-bit addresses, 32-bit index, 32-bit index with offset, 64-bit address) can affect how useful the object index is. Here is a program which assumes you have 32-bit index in a 64-bit JVM. import sun.misc.Unsafe; import java.lang.reflect.Field; import java.util.Arrays; …