Title here
Summary here
Arrays in Java are a numbered sequence of elements of a specific length. In typical Java code, arrays are quite common and useful in many scenarios.
public class Arrays {
public static void main(String[] args) {
// Here we create an array 'a' that will hold exactly
// 5 integers. The type of elements and length are both
// part of the array's type. By default an array is
// zero-valued, which for integers means 0s.
int[] a = new int[5];
System.out.println("emp: " + java.util.Arrays.toString(a));
// We can set a value at an index using the
// array[index] = value syntax, and get a value with
// array[index].
a[4] = 100;
System.out.println("set: " + java.util.Arrays.toString(a));
System.out.println("get: " + a[4]);
// The length property returns the length of an array.
System.out.println("len: " + a.length);
// Use this syntax to declare and initialize an array
// in one line.
int[] b = {1, 2, 3, 4, 5};
System.out.println("dcl: " + java.util.Arrays.toString(b));
// In Java, you can't use '...' to have the compiler count
// the number of elements for you. The size must be explicitly
// specified or inferred from the initializer list.
// Java doesn't have a direct equivalent to Go's index-based
// initialization. You would need to initialize the array
// and then set specific elements.
int[] c = new int[5];
c[0] = 100;
c[3] = 400;
c[4] = 500;
System.out.println("idx: " + java.util.Arrays.toString(c));
// Array types are one-dimensional, but you can
// compose types to build multi-dimensional data
// structures.
int[][] twoD = new int[2][3];
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
twoD[i][j] = i + j;
}
}
System.out.println("2d: " + java.util.Arrays.deepToString(twoD));
// You can create and initialize multi-dimensional
// arrays at once too.
twoD = new int[][] {
{1, 2, 3},
{1, 2, 3}
};
System.out.println("2d: " + java.util.Arrays.deepToString(twoD));
}
}
Note that arrays in Java are printed using java.util.Arrays.toString()
for one-dimensional arrays and java.util.Arrays.deepToString()
for multi-dimensional arrays.
When you run this program, you’ll see output similar to this:
emp: [0, 0, 0, 0, 0]
set: [0, 0, 0, 0, 100]
get: 100
len: 5
dcl: [1, 2, 3, 4, 5]
idx: [100, 0, 0, 400, 500]
2d: [[0, 1, 2], [1, 2, 3]]
2d: [[1, 2, 3], [1, 2, 3]]
Java arrays are similar to those in many other languages, but there are some key differences from Go:
[]
after the type to declare arrays, not before the type as in Go....
).java.util.Arrays
, as Java doesn’t have built-in pretty-printing for arrays.Despite these differences, the core concept of arrays as fixed-size, indexed collections of elements remains the same.