Var-Args - Revision history

Suhridk at 15:53, 13 September 2011

2011-09-13T15:53:13Z

2011-09-08T06:09:45Z

2011-09-08T05:58:47Z

2011-08-26T05:45:29Z

2011-08-24T11:59:20Z

2011-08-24T11:58:30Z

2011-08-24T11:49:03Z

2011-08-24T11:44:45Z

2011-08-24T11:44:23Z

2011-08-22T10:37:44Z

Created page with "* Var-args are used to defined methods with variable argument lists. * Syntax <type>... <varargname>"

New page

* Var-args are used to defined methods with variable argument lists.
* Syntax <type>... <varargname>

@@ Line 36: / Line 36: @@
 </syntaxhighlight>
-* For a var-args method, the method parameters can also be passed as an array argument.
+* For a var-args method, the method parameters can also be passed as an array argument. In this case, it will be treated as a non var-args call, since the argument and the parameter both match.
 * Example:

← Older revision		Revision as of 06:09, 8 September 2011
Line 92:		Line 92:

	[[Category:OCPJP]]		[[Category:OCPJP]]
		+
		+
		+	== Var-Args Overloading ==
		+
		+	* Because arguments to var-arg methods are implicitly passed as arrays, the following will NOT compile, both the foo()'s have the same signature:
		+
		+	<syntaxhighlight lang="java5">
		+
		+	private static void foo(int...ia2) {
		+
		+	}
		+
		+	private static void foo(int[] ia2) {
		+
		+	}
		+
		+	</syntaxhighlight>

@@ Line 24: / Line 24: @@
 * The ellipsis can be located anywhere e.g. (int... nums) or (int ...nums) or (int ... nums) is fine.
-* Essentially the method argument is treated as an array within the method. so nums is an int[] array.
+* Essentially the method arguments are implicitly converted into an array and passed to the method. so nums is an int[] array.
 * Example main() can be legally rewritten as :
@@ Line 36: / Line 36: @@
 </syntaxhighlight>
-* Where it differs from an array is that For a var-args method, the method parameter can also be passed "normally", in addition to being passed as an array.
+* For a var-args method, the method parameters can also be passed as an array argument.
 * Example:

@@ Line 36: / Line 36: @@
 </syntaxhighlight>
-* Where it differs from an array is that For a var-args method, the method parameter can be passed "normally", instead of being passed as an array
+* Where it differs from an array is that For a var-args method, the method parameter can also be passed "normally", in addition to being passed as an array.
 * Example:
@@ Line 44: / Line 44: @@
 	public static void main(String[] args) {
-             System.out.println(vasum(2, 3, 4));	              //Varargs invocation
+             System.out.println(vasum(2, 3, 4));	              //Variable arguments invocation
-	    System.out.println(arrsum(new int[] {2, 3, 4}));  //Array invocation
+            System.out.println(vasum(new int[] {1, 2, 3});    //Array invocation also OK for var-args
+	}

@@ Line 25: / Line 25: @@
 * The ellipsis can be located anywhere e.g. (int... nums) or (int ...nums) or (int ... nums) is fine.
 * Essentially the method argument is treated as an array within the method. so nums is an int[] array.
 * Where it differs from an array is that For a var-args method, the method parameter can be passed "normally", instead of being passed as an array

← Older revision		Revision as of 11:58, 24 August 2011
Line 54:		Line 54:
	}		}

		+	}
		+
		+	</syntaxhighlight>
		+
		+
		+	* The var-args must be the last parameter in the method's signature. Why ? To resolve situations like this :
		+
		+	<syntaxhighlight lang="java5">
		+
		+	sum2(2, 3);
		+
		+	public static void sum2(int a, int... nums) {
		+	}
		+
		+	</syntaxhighlight>
		+
		+	* Only one var-arg can be declared in the method (even if the var-args are of different types)
		+
		+	<syntaxhighlight lang="java5">
		+
		+	public static void sum3( String... strs, int... nums) { //ILLEGAL
	}		}

← Older revision		Revision as of 11:44, 24 August 2011
Line 25:		Line 25:
	* Essentially the method argument is treated as an array within the method. so nums is an int[] array.		* Essentially the method argument is treated as an array within the method. so nums is an int[] array.

		+	[[Category:OCPJP]]

	</syntaxhighlight>		</syntaxhighlight>

← Older revision		Revision as of 11:44, 24 August 2011
Line 1:		Line 1:
	* Var-args are used to defined methods with variable argument lists.		* Var-args are used to defined methods with variable argument lists.
	* Syntax <type>... <varargname>		* Syntax <type>... <varargname>
		+	* Example:
		+
		+	<syntaxhighlight lang="java5">
		+
		+	public class VarArgs {
		+
		+	public static void main(String[] args) {
		+	System.out.println(sum(2, 3, 4));
		+	}
		+
		+	public static int sum(int... nums) {
		+	int sum = 0;
		+	for(int i : nums) {
		+	sum += i;
		+	}
		+	return sum;
		+	}
		+
		+	}
		+
		+
		+	* The ellipsis can be located anywhere e.g. (int... nums) or (int ...nums) or (int ... nums) is fine.
		+	* Essentially the method argument is treated as an array within the method. so nums is an int[] array.
		+
		+
		+	</syntaxhighlight>