In this article, we’ll go through how you can initialize an array in java, through detailed examples.
1. How to Initialize a 1D Array
To create a one-dimension array in Java, the formula is the following:
Object_type_or_primitive[] array_name = new Object_type_or_primitive[int_or_short_value]
For example, we could initialize an array of type Person
and length 3, with the following command:
Person[] persons = new Person[3];
In addition, we could use primitive types, so to create an array of type short
and length 100, the command is the following:
short[] numbers = new short[100];
Should you like to declare and initialize an array in one command, you could use the following formula:
Object_type_or_primitive[] array_name = { value_1, value_2, value_3, ..., value_n}
So, to initialize the array in section 1, the command is the following:
String[] names = {"Akis", "Giorgos", "Nikos", "Dimitris", "Giannis", "Kostas"};
2. How to Initialize a 2D Array in Java
To initialize a 2d array, the formula is the following:
Object_type_or_primitive[][] array_name = new Object_type_or_primitive[int_or_short_value_rows] [int_or_short_value_columns]
For example, we could initialize an array of type Person
with 3 rows and 3 columns, with the following command:
Person[][] persons = new Person[3][3];
Should you like to declare and initialize a Java array in one command, you could use the following formula:
Object_type_or_primitive[][] array_name = { {value_1,value_2}, {value_3,value_4}, ... , {value_n,value_m}}
So, to create a 3 X 3 with Xs and Os (like tic-tac-toe), we would write the following:
String[][] names = { {"X", "X", "X"}, {"O", "X", "O"}, {"O", "X", "O"} };
3. How to Initialize a 3D Array in Java
To initialize a 3d array, the formula is the following:
Object_type_or_primitive[][][] array_name = new Object_type_or_primitive[int_or_short_value_rows] [int_or_short_value_columns] [int_or_short_value_columns]
For example, we could initialize an array of type int
with a total size of 27 with the following command:
Person[][][] persons = new Person[3][3][3];
Should you like to declare and initialize a java array in one command, you could use the following formula:
Object_type_or_primitive[][][] array_name = { { {value_1,value_2}, {value_3,value_4}, ... , {value_n,value_m} }, { {value_1,value_2}, {value_3,value_4}, ... , {value_n,value_m} }, { {value_1,value_2}, {value_3,value_4}, ... , {value_n,value_m} }, ... }
So, to create a int
array of size 3 X 3 X 3 with numbers, we would write the following:
int [][][] numbers = { { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} }, { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} }, { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} }, };
4. Conclusion
By now you should be able to initialize a 1D, 2D, or even a 3D array either by just declaring its size of it or by filling it during initialization. To learn everything about Java Arrays, you can click here.