Runtime.version()
Since Java 9, you can use Runtime.version()
, which returns a Runtime.Version
:
Runtime.Version version = Runtime.version();
What about getting the version from the package meta infos:
String version = Runtime.class.getPackage().getImplementationVersion();
Prints out something like:
1.7.0_13
Here's the implementation in JOSM:
/**
* Returns the Java version as an int value.
* @return the Java version as an int value (8, 9, etc.)
* @since 12130
*/
public static int getJavaVersion() {
String version = System.getProperty("java.version");
if (version.startsWith("1.")) {
version = version.substring(2);
}
// Allow these formats:
// 1.8.0_72-ea
// 9-ea
// 9
// 9.0.1
int dotPos = version.indexOf('.');
int dashPos = version.indexOf('-');
return Integer.parseInt(version.substring(0,
dotPos > -1 ? dotPos : dashPos > -1 ? dashPos : 1));
}
Does not work, need --pos
to evaluate double:
String version = System.getProperty("java.version");
System.out.println("version:" + version);
int pos = 0, count = 0;
for (; pos < version.length() && count < 2; pos++) {
if (version.charAt(pos) == '.') {
count++;
}
}
--pos; //EVALUATE double
double dversion = Double.parseDouble(version.substring(0, pos));
System.out.println("dversion:" + dversion);
return dversion;
}
The simplest way (java.specification.version):
double version = Double.parseDouble(System.getProperty("java.specification.version"));
if (version == 1.5) {
// 1.5 specific code
} else {
// ...
}
or something like (java.version):
String[] javaVersionElements = System.getProperty("java.version").split("\\.");
int major = Integer.parseInt(javaVersionElements[1]);
if (major == 5) {
// 1.5 specific code
} else {
// ...
}
or if you want to break it all up (java.runtime.version):
String discard, major, minor, update, build;
String[] javaVersionElements = System.getProperty("java.runtime.version").split("\\.|_|-b");
discard = javaVersionElements[0];
major = javaVersionElements[1];
minor = javaVersionElements[2];
update = javaVersionElements[3];
build = javaVersionElements[4];
Example for Apache Commons Lang:
import org.apache.commons.lang.SystemUtils;
Float version = SystemUtils.JAVA_VERSION_FLOAT;
if (version < 1.4f) {
// legacy
} else if (SystemUtils.IS_JAVA_1_5) {
// 1.5 specific code
} else if (SystemUtils.isJavaVersionAtLeast(1.6f)) {
// 1.6 compatible code
} else {
// dodgy clause to catch 1.4 :)
}
Here is the answer from @mvanle, converted to Scala:
scala> val Array(javaVerPrefix, javaVerMajor, javaVerMinor, _, _) = System.getProperty("java.runtime.version").split("\\.|_|-b")
javaVerPrefix: String = 1
javaVerMajor: String = 8
javaVerMinor: String = 0
If you can have dependency to apache utils you can use org.apache.commons.lang3.SystemUtils.
System.out.println("Is Java version at least 1.8: " + SystemUtils.isJavaVersionAtLeast(JavaVersion.JAVA_1_8));
Just a note that in Java 9 and above, the naming convention is different. System.getProperty("java.version")
returns "9"
rather than "1.9"
.
Don't know another way of checking this, but this: http://java.sun.com/j2se/1.5.0/docs/api/java/lang/System.html#getProperties()" implies "java.version" is a standard system property so I'd expect it to work with other JVMs.
java.version
is a system property that exists in every JVM. There are two possible formats for it:
1.6.0_23
, 1.7.0
, 1.7.0_80
, 1.8.0_211
9.0.1
, 11.0.4
, 12
, 12.0.1
Here is a trick to extract the major version: If it is a 1.x.y_z
version string, extract the character at index 2 of the string. If it is a x.y.z
version string, cut the string to its first dot character, if one exists.
private static int getVersion() {
String version = System.getProperty("java.version");
if(version.startsWith("1.")) {
version = version.substring(2, 3);
} else {
int dot = version.indexOf(".");
if(dot != -1) { version = version.substring(0, dot); }
} return Integer.parseInt(version);
}
Now you can check the version much more comfortably:
if(getVersion() < 6) {
// ...
}
Source: Stackoverflow.com