Java array


An array is the ability to combine multiple values.

Array variable definition

When dealing with arrays, assign the array to an array type variable. Array variable definition int type and String type


The int type is an array that has a numerical value as an element. String type is an array that has a character string as an element. The first letter of String is uppercase. Example of int type array

int[] numbers = {1,5,10};

Example of an array of type String

String[] names = {"Sato","Suzuki","Takahashi"};

Numbers such as "0, 1, 2 ..." are assigned to the elements of the array in order from the front. Each element of the array can be obtained by using the array name [index number]. [Example]

String[] names = {"Sato","Suzuki","Takahashi"};
  System.out.println("Name is"+names[0]+"is");

Overwriting elements of an array

String[] names = {"Sato","Suzuki","Takahashi"};
  System.out.println("Name is"+names[0]+"is");
  names[0] = "Ueno";
  System.out.println("Name is"+names[0]+"is");

It can be overridden with names [index] = "element" ;. In the above example, the output result of the console will be Sato and Ueno.

Array iteration

Iterative processing can be performed using the for statement. [Example]

String[] names = {"Sato","Suzuki","Takahashi"};
  for (int x = 0;x < 3;x++){
  System.out.println("Name is"+names[x]+"is");

In the above example, the three indexes 0 to 2 are called from names. length length is a function that counts the number of elements. You can iterate using the for statement and length above. It can be rewritten by changing the conditional expression x <3 of the for statement to the array .length. [Example]

String[] names = {"Sato","Suzuki","Takahashi"};
  for (int x = 0;x < names.length;x++){
  System.out.println("Name is"+names[x]+"is");

If you write as above, you don't have to worry about the number of elements in the array. So I think this is easier to use. However, there is also a simpler for statement. It's an array extension for statement.

Array extension for statement

The for statement has an extended for statement for arrays. If you use this, you can write the for statement more simply.

for (Data type variable name:Array name) {
Repeated processing;


String[] names = {"Sato","Suzuki","Takahashi"};
  for (String name:names){
  System.out.println("Name is"+name+"is");

In the above example, String is the data type, name is the variable name, and names is the array name. Compared to the for statement that used length, the extended for statement assigns the array element itself to the variable. I wrote it loosely for my understanding, but I think this is the easiest to use.

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