Some methods below: getProperty(...), arrayCopy(...)
■ This class creates the
System.in, System.out, and System.err streams.
String getProperty(...) method
■ System.getProperty(“user.dir”) returns the current
directory.
■ Other
property keys obtainable are:
java.version Java Runtime Environment
version
java.vendor Java Runtime Environment
vendor
java.vendor.url Java vendor URL
java.home Java installation directory
java.vm.specification.version Java Virtual Machine specification version
java.vm.specification.vendor Java Virtual Machine specification vendor
java.vm.specification.name Java Virtual Machine specification name
java.vm.version Java Virtual Machine
implementation version
java.vm.vendor Java Virtual Machine
implementation vendor
java.vm.name Java Virtual Machine
implementation name
java.specification.version Java Runtime Environment specification
version
java.specification.vendor Java Runtime Environment specification
vendor
java.specification.name Java Runtime Environment specification
name
java.class.version Java class format version number
java.class.path Java class path
java.ext.dirs Path of extension
directory or directories
os.name Operating system
name
os.arch Operating system
architecture
os.version Operating system
version
file.separator File separator
("/" on UNIX)
path.separator Path separator
(":" on UNIX)
line.separator Line separator
("\n" on UNIX)
user.name User's account name
user.home User's home directory
user.dir User's current
working directory
■ Copies a len number of elements from the source array, beginning at the srcIndex position, to the dstIndex position of the destination array.
■ This snippet copies the three elements 1 2 3 from the first array, which are located at index zero, into the second array, to reside in place of the second array’s e f g, which are located starting at index 4.
String[ ] a1 =
{"1","2","3","4","5","6","7","8","9"};
String[ ] a2 =
{"a","b","c","d","e","f","g","h","i"
};
System.arraycopy(a1, 0,
a2, 4, 3 );
List aList =
Arrays.asList(a1) ;
System.out.println(aList);
List bList =
Arrays.asList(a2) ;
System.out.println(bList);
■ This code shifts all the elements of the array to the right by two positions, printing a b a b c d e f g.
Notice how the first two shifted positions retain their original
values, and how the shifted-out positions on the far right simply lose their
old values. The original array length
is not changed. i.e.
String[ ] a2 =
{"a","b","c","d","e","f","g","h","i"
};
System.out.println(a2.length);
System.arraycopy(a2, 0,
a2, 2, a2.length-2 );
List bList =
Arrays.asList(a2) ;
System.out.println(bList);