J2SE 5.0 (or JDK 5), codenamed Tiger, was released on September 30, 2004. It was renumbered to 5.0 instead of 1.5.
JDK 5 New Language Features
JDK 5 is a major update, which introduces many important new language features.
Generics (JSR 14)
Provide compile-time type-safety for Collection and eliminate the need for most type-cast. See "Generics".
Annotations (JSR 175)
Annotations (or metadata) allow classes and methods to be tagged with additional data, which can then be pre-processed by the compiler. See "Annotations".
Autoboxing/unboxing (JSR 201)
Automatic conversion between primitive types (such as int, double) and primitive wrapper classes (such as Integer, Double). See "Java Collection Framework".
Enumerations (JSR 201)
The new keyword enum creates a type-safe, ordered list of values. See "Enumerations".
Varargs (Variable Arguments)
The last method's formal parameter can be declared using a type name followed by three dots (e.g., String... messages), which accepts any numbers of actual parameters packed in an array. For example,
public class JDK5TryVarargs {
public static void main(String[] args) {
greets("Hello", "Peter", "Paul");
}
public static void greets(String greeting, String... names) {
System.out.print(greeting + ",");
// varargs received as an array
for (int i = 0; i < names.length; ++i) {
System.out.print(" " + names[i]);
}
System.out.println();
}
}
Enhanced for-each loop: for ( : )
New construct for iterating thru a Java Collection. For example,
import java.util.List;
import java.util.ArrayList;
public class JDK5TryForEach {
public static void main(String[] args) {
int[] marks = {11, 22, 33, 44, 55}; // array
// JDK 5's new for-each loop
for (int mark : marks) {
System.out.println(mark);
}
List<String> fruits = new ArrayList<>(); // Collection
fruits.add("apple");
fruits.add("orange");
for (String fruit : fruits) {
System.out.println(fruit);
}
}
}
static import Statement
For importing members (fields and methods) as public static. Can be referenced without specifying the class name.
import static java.lang.Math.PI; // import a constant in a class public class JDK5TryStaticImport { public static void main(String[] args) { System.out.println(PI); // No classname needed } }
JDK 5 Library Changes
[TODO]
JDK 5 Other New Features
[TODO]
REFERENCES & RESOURCES