SINGLE-DIMENSIONAL ARRAYS - Introduction to Java Programming: Comprehensive Version - page 257

You can write a loop to copy every element from the source array to the corresponding element
in the target array. The following code, for instance, copies sourceArray to targetArray
using a for loop.

int [] sourceArray = { 2 , 3 , 1 , 5 , 10 };
int [] targetArray = new int [sourceArray.length];
for ( int i = 0 ; i < sourceArray.length; i++) {
targetArray[i] = sourceArray[i];
}

Another approach is to use the arraycopy method in the java.lang.System class to copy
arrays instead of using a loop. The syntax for arraycopy is:

arraycopy method

arraycopy(sourceArray, srcPos, targetArray, tarPos, length);

The parameters srcPos and tarPos indicate the starting positions in sourceArray and
targetArray , respectively. The number of elements copied from sourceArray to targ-
etArray is indicated by length . For example, you can rewrite the loop using the following
statement:

System.arraycopy(sourceArray, 0 , targetArray, 0 , sourceArray.length);

The arraycopy method does not allocate memory space for the target array. The target array
must have already been created with its memory space allocated. After the copying takes place,
targetArray and sourceArray have the same content but independent memory locations.

Note
The arraycopy method violates the Java naming convention. By convention, this
method should be named arrayCopy (i.e., with an uppercase C).

7.13

✓ ✓

Use the arraycopy method to copy the following array to a target array t :
int [] source = { 3 , 4 , 5 };

Check

Point

7.14

Once an array is created, its size cannot be changed. Does the following code resize
the array?

int [] myList;
myList = new int [ 10 ];
// Sometime later you want to assign a new array to myList
myList = new int [ 20 ];

7.6 Passing Arrays to Methods
When passing an array to a method, the reference of the array is passed to the method.

Key
Point

Just as you can pass primitive type values to methods, you can also pass arrays to methods.
For example, the following method displays the elements in an int array:

public static void printArray( int [] array) {
for ( int i = 0 ; i < array.length; i++) {
System.out.print(array[i] + " " );
}
}

You can invoke it by passing an array. For example, the following statement invokes the
printArray method to display 3 , 1 , 2 , 6 , 4 , and 2 .

printArray( new int []{ 3 , 1 , 2 , 6 , 4 , 2 });