JavaEnvUtils (Apache Ant API)

java.lang.Object
- org.apache.tools.ant.util.JavaEnvUtils

```
public final class JavaEnvUtils
extends java.lang.Object
```
A set of helper methods related to locating executables or checking conditions of a given Java installation.
Starting with Java 10 we've stopped adding JAVA_ and VERSION_ attributes for new major version numbers of the JVM.

Since:

Ant 1.5

Field Summary

Fields
Modifier and Type	Field and Description
`static java.lang.String`	`JAVA_1_0` Version constant for Java 1.0
`static java.lang.String`	`JAVA_1_1` Version constant for Java 1.1
`static java.lang.String`	`JAVA_1_2` Version constant for Java 1.2
`static java.lang.String`	`JAVA_1_3` Version constant for Java 1.3
`static java.lang.String`	`JAVA_1_4` Version constant for Java 1.4
`static java.lang.String`	`JAVA_1_5` Version constant for Java 1.5
`static java.lang.String`	`JAVA_1_6` Version constant for Java 1.6
`static java.lang.String`	`JAVA_1_7` Version constant for Java 1.7
`static java.lang.String`	`JAVA_1_8` Version constant for Java 1.8
`static java.lang.String`	`JAVA_1_9` Deprecated. use #JAVA_9 instead
`static java.lang.String`	`JAVA_9` Version constant for Java 9
`static int`	`VERSION_1_0` Number Version constant for Java 1.0
`static int`	`VERSION_1_1` Number Version constant for Java 1.1
`static int`	`VERSION_1_2` Number Version constant for Java 1.2
`static int`	`VERSION_1_3` Number Version constant for Java 1.3
`static int`	`VERSION_1_4` Number Version constant for Java 1.4
`static int`	`VERSION_1_5` Number Version constant for Java 1.5
`static int`	`VERSION_1_6` Number Version constant for Java 1.6
`static int`	`VERSION_1_7` Number Version constant for Java 1.7
`static int`	`VERSION_1_8` Number Version constant for Java 1.8
`static int`	`VERSION_1_9` Deprecated. use #VERSION_9 instead
`static int`	`VERSION_9` Number Version constant for Java 9

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static java.io.File`	`createVmsJavaOptionFile(java.lang.String[] cmds)` Writes the command into a temporary DCL script and returns the corresponding File object.
`static java.lang.String`	`getJavaHome()` Return the value of ${java.home}
`static java.lang.String`	`getJavaVersion()` Returns the version of Java this class is running under.
`static int`	`getJavaVersionNumber()` Deprecated. use #getParsedJavaVersion instead
`static java.lang.String`	`getJdkExecutable(java.lang.String command)` Finds an executable that is part of a JDK installation based on the java.home system property.
`static java.lang.String`	`getJreExecutable(java.lang.String command)` Finds an executable that is part of a JRE installation based on the java.home system property.
`static java.util.Vector<java.lang.String>`	`getJrePackages()` get a vector of strings of packages built into that platforms runtime jar(s)
`static java.util.Vector<java.lang.String>`	`getJrePackageTestCases()` Testing helper method; kept here for unification of changes.
`static DeweyDecimal`	`getParsedJavaVersion()` Returns the version of Java this class is running under.
`static boolean`	`isApacheHarmony()` Checks whether the current VM is Apache Harmony.
`static boolean`	`isAtLeastJavaVersion(java.lang.String version)` Compares the current Java version to the passed in String - assumes the argument is one of the constants defined in this class.
`static boolean`	`isClasspathBased()` Checks whether the current Java VM is GNU Classpath
`static boolean`	`isGij()` Checks whether the current Java VM is the GNU interpreter gij or we are running in a gcj precompiled binary.
`static boolean`	`isJavaVersion(java.lang.String version)` Compares the current Java version to the passed in String - assumes the argument is one of the constants defined in this class.
`static boolean`	`isKaffe()` Checks whether the current Java VM is Kaffe.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - JAVA_1_0
```
public static final java.lang.String JAVA_1_0
```
    Version constant for Java 1.0
    
    See Also:
    
    Constant Field Values
  - VERSION_1_0
```
public static final int VERSION_1_0
```
    Number Version constant for Java 1.0
    
    See Also:
    
    Constant Field Values
  - JAVA_1_1
```
public static final java.lang.String JAVA_1_1
```
    Version constant for Java 1.1
    
    See Also:
    
    Constant Field Values
  - VERSION_1_1
```
public static final int VERSION_1_1
```
    Number Version constant for Java 1.1
    
    See Also:
    
    Constant Field Values
  - JAVA_1_2
```
public static final java.lang.String JAVA_1_2
```
    Version constant for Java 1.2
    
    See Also:
    
    Constant Field Values
  - VERSION_1_2
```
public static final int VERSION_1_2
```
    Number Version constant for Java 1.2
    
    See Also:
    
    Constant Field Values
  - JAVA_1_3
```
public static final java.lang.String JAVA_1_3
```
    Version constant for Java 1.3
    
    See Also:
    
    Constant Field Values
  - VERSION_1_3
```
public static final int VERSION_1_3
```
    Number Version constant for Java 1.3
    
    See Also:
    
    Constant Field Values
  - JAVA_1_4
```
public static final java.lang.String JAVA_1_4
```
    Version constant for Java 1.4
    
    See Also:
    
    Constant Field Values
  - VERSION_1_4
```
public static final int VERSION_1_4
```
    Number Version constant for Java 1.4
    
    See Also:
    
    Constant Field Values
  - JAVA_1_5
```
public static final java.lang.String JAVA_1_5
```
    Version constant for Java 1.5
    
    See Also:
    
    Constant Field Values
  - VERSION_1_5
```
public static final int VERSION_1_5
```
    Number Version constant for Java 1.5
    
    See Also:
    
    Constant Field Values
  - JAVA_1_6
```
public static final java.lang.String JAVA_1_6
```
    Version constant for Java 1.6
    
    See Also:
    
    Constant Field Values
  - VERSION_1_6
```
public static final int VERSION_1_6
```
    Number Version constant for Java 1.6
    
    See Also:
    
    Constant Field Values
  - JAVA_1_7
```
public static final java.lang.String JAVA_1_7
```
    Version constant for Java 1.7
    
    See Also:
    
    Constant Field Values
  - VERSION_1_7
```
public static final int VERSION_1_7
```
    Number Version constant for Java 1.7
    
    See Also:
    
    Constant Field Values
  - JAVA_1_8
```
public static final java.lang.String JAVA_1_8
```
    Version constant for Java 1.8
    
    See Also:
    
    Constant Field Values
  - VERSION_1_8
```
public static final int VERSION_1_8
```
    Number Version constant for Java 1.8
    
    See Also:
    
    Constant Field Values
  - JAVA_1_9
```
@Deprecated
public static final java.lang.String JAVA_1_9
```
    Deprecated. use #JAVA_9 instead
    
    Version constant for Java 1.9
    
    See Also:
    
    Constant Field Values
  - VERSION_1_9
```
@Deprecated
public static final int VERSION_1_9
```
    Deprecated. use #VERSION_9 instead
    
    Number Version constant for Java 1.9
    
    See Also:
    
    Constant Field Values
  - JAVA_9
```
public static final java.lang.String JAVA_9
```
    Version constant for Java 9
    
    Since:
    
    Ant 1.9.8
    
    See Also:
    
    Constant Field Values
  - VERSION_9
```
public static final int VERSION_9
```
    Number Version constant for Java 9
    
    Since:
    
    Ant 1.9.8
    
    See Also:
    
    Constant Field Values
- Method Detail
  - getJavaVersion
```
public static java.lang.String getJavaVersion()
```
    Returns the version of Java this class is running under.
    Up until Java 8 Java version numbers were 1.VERSION - e.g. 1.8.x for Java 8, starting with Java 9 it became 9.x.
    
    Returns:
    
    the version of Java as a String, e.g. "1.6" or "9"
  - getJavaVersionNumber
```
@Deprecated
public static int getJavaVersionNumber()
```
    Deprecated. use #getParsedJavaVersion instead
    
    Returns the version of Java this class is running under.
    This number can be used for comparisons.
    
    Returns:
    
    the version of Java as a number 10x the major/minor, e.g Java1.5 has a value of 15 and Java9 the value 90 - major will be 1 for all versions of Java prior to Java 9, minor will be 0 for all versions of Java starting with Java 9.
  - getParsedJavaVersion
```
public static DeweyDecimal getParsedJavaVersion()
```
    Returns the version of Java this class is running under.
    This number can be used for comparisons.
    
    Returns:
    
    the version of Java as major.minor, e.g Java1.5 has a value of 1.5 and Java9 the value 9 - major will be 1 for all versions of Java prior to Java 9, minor will be 0 for all versions of Java starting with Java 9.
  - isJavaVersion
```
public static boolean isJavaVersion(java.lang.String version)
```
    Compares the current Java version to the passed in String - assumes the argument is one of the constants defined in this class. Note that Ant now requires JDK 1.5+ so JAVA_1_0 through JAVA_1_4 need no longer be tested for.
    
    Parameters:
    
    version - the version to check against the current version.
    
    Returns:
    
    true if the version of Java is the same as the given version.
    
    Since:
    
    Ant 1.5
  - isAtLeastJavaVersion
```
public static boolean isAtLeastJavaVersion(java.lang.String version)
```
    Compares the current Java version to the passed in String - assumes the argument is one of the constants defined in this class. Note that Ant now requires JDK 1.5+ so JAVA_1_0 through JAVA_1_4 need no longer be tested for.
    
    Parameters:
    
    version - the version to check against the current version.
    
    Returns:
    
    true if the version of Java is the same or higher than the given version.
    
    Since:
    
    Ant 1.7
  - isKaffe
```
public static boolean isKaffe()
```
    Checks whether the current Java VM is Kaffe.
    
    Returns:
    
    true if the current Java VM is Kaffe.
    
    Since:
    
    Ant 1.6.3
    
    See Also:
    
    http://www.kaffe.org/
  - isClasspathBased
```
public static boolean isClasspathBased()
```
    Checks whether the current Java VM is GNU Classpath
    
    Returns:
    
    true if the version of Java is GNU Classpath
    
    Since:
    
    Ant 1.9.1
  - isGij
```
public static boolean isGij()
```
    Checks whether the current Java VM is the GNU interpreter gij or we are running in a gcj precompiled binary.
    
    Returns:
    
    true if the current Java VM is gcj/gij.
    
    Since:
    
    Ant 1.8.2
  - isApacheHarmony
```
public static boolean isApacheHarmony()
```
    Checks whether the current VM is Apache Harmony.
    
    Returns:
    
    true if the current VM is Apache Harmony.
    
    Since:
    
    Ant 1.8.2
  - getJreExecutable
```
public static java.lang.String getJreExecutable(java.lang.String command)
```
    Finds an executable that is part of a JRE installation based on the java.home system property.
    java, keytool, policytool, orbd, rmid, rmiregistry, servertool and tnameserv are JRE executables on Sun based JRE's.
    
    You typically find them in JAVA_HOME/jre/bin if JAVA_HOME points to your JDK installation. JDK < 1.2 has them in the same directory as the JDK executables.
    
    Parameters:
    
    command - the java executable to find.
    
    Returns:
    
    the path to the command.
    
    Since:
    
    Ant 1.5
  - getJdkExecutable
```
public static java.lang.String getJdkExecutable(java.lang.String command)
```
    Finds an executable that is part of a JDK installation based on the java.home system property.
    You typically find them in JAVA_HOME/bin if JAVA_HOME points to your JDK installation.
    
    Parameters:
    
    command - the java executable to find.
    
    Returns:
    
    the path to the command.
    
    Since:
    
    Ant 1.5
  - getJrePackageTestCases
```
public static java.util.Vector<java.lang.String> getJrePackageTestCases()
```
    Testing helper method; kept here for unification of changes.
    
    Returns:
    
    a list of test classes depending on the java version.
  - getJrePackages
```
public static java.util.Vector<java.lang.String> getJrePackages()
```
    get a vector of strings of packages built into that platforms runtime jar(s)
    
    Returns:
    
    list of packages.
  - createVmsJavaOptionFile
```
public static java.io.File createVmsJavaOptionFile(java.lang.String[] cmds)
                                            throws java.io.IOException
```
    Writes the command into a temporary DCL script and returns the corresponding File object. It is the job of the caller to delete the file on exit.
    
    Parameters:
    
    cmds - the command.
    
    Returns:
    
    the file containing the command.
    
    Throws:
    
    java.io.IOException - if there is an error writing to the file.
  - getJavaHome
```
public static java.lang.String getJavaHome()
```
    Return the value of ${java.home}
    
    Returns:
    
    the java home value.

Class JavaEnvUtils

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

JAVA_1_0

VERSION_1_0

JAVA_1_1

VERSION_1_1

JAVA_1_2

VERSION_1_2

JAVA_1_3

VERSION_1_3

JAVA_1_4

VERSION_1_4

JAVA_1_5

VERSION_1_5

JAVA_1_6

VERSION_1_6

JAVA_1_7

VERSION_1_7

JAVA_1_8

VERSION_1_8

JAVA_1_9

VERSION_1_9

JAVA_9

VERSION_9

Method Detail

getJavaVersion

getJavaVersionNumber

getParsedJavaVersion

isJavaVersion

isAtLeastJavaVersion

isKaffe

isClasspathBased

isGij

isApacheHarmony

getJreExecutable

getJdkExecutable

getJrePackageTestCases

getJrePackages

createVmsJavaOptionFile

getJavaHome