Some array operations (declare, initialize, reassign)
In this section we will learn how to wok with array of
object type and also with primitive type. In code code given below we will
declare array in different ways for both object and primitive type. After
declaration, initialize with primitive type values and objects then reassign
values in some declared arrays.
ArrayOperation.java
public class ArrayOperation {
public static void main(String[] args) {
// declare array of object type
Array[] arr1; // uninitialized array variable
Array[] arr2 = new Array[5]; // initialize with Null references
Array[] arr3 = new Array[4];
// initialize array with object of Array type.
arr1 = new Array[]{new Array(), new Array()};
//print the length of three declared arrays
System.out.println("Length of array 'arr1' : " + arr1.length);
System.out.println("Length of array 'arr2' : " + arr2.length);
System.out.println("Length of array 'arr3' : " + arr3.length);
// print the elements of array 'arr2'
System.out.println("Elements of array 'arr2'.");
for (int i = 0; i < arr2.length; i++) {
System.out.println("b[" + i + "]=" + arr2[i]);
}
// assign arr2 to array arr1
arr1 = arr2;
System.out.println("Now length of array 'arr1' : " + arr1.length);
// Arrays of primitives:
int[] a; // Null reference
int[] b = new int[5];
int[] c = new int[4];
int[] d = {11, 47, 93};
// fill values in integer array 'c'
for (int i = 0; i < c.length; i++) {
c[i] = i;
}
// print length of arrays of primitive type
System.out.println("Length of integer array 'b' = " + b.length);
System.out.println("Length of integer array 'c' = " + c.length);
System.out.println("Length of integer array 'd' = " + d.length);
// print all the elements of array 'b'
for (int i = 0; i < b.length; i++) {
System.out.println("f[" + i + "]=" + b[i]);
}
// assign array 'd' to array 'a' and print the length of array 'a'
a = d;
System.out.println("Now length of array 'a' : " + a.length);
// assign some new values in array 'a' and then print array 'a'.
a = new int[]{1, 2};
System.out.println("Final length of array 'a' : " + a.length);
}
}
class Array {
}
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Output :
Length of array 'arr1' : 2 Length of array 'arr2' : 5 Length of array 'arr3' : 4 Elements of array 'arr2'. b[0]=null b[1]=null b[2]=null b[3]=null b[4]=null Now length of array 'arr1' : 5 Length of integer array 'b' = 5 Length of integer array 'c' = 4 Length of integer array 'd' = 3 f[0]=0 f[1]=0 f[2]=0 f[3]=0 f[4]=0 Now length of array 'a' : 3 Final length of array 'a' : 2 |