[Java] Array

Reference "Introduction to Java that can be clearly understood p133 ~ p164"

Chapter 4 Summary

There was an ambiguous part about the arrangement, so I reviewed it with "Clearly understand".

First, in the image below, the meaning of using an array is


If you write it like this ・ It is troublesome when the number of subjects increases ・ Cannot be processed together

Inconvenience such as occurs.

Therefore, a data structure that stores a plurality of data of the same type in the order of arrangement is an "array".

** * Note that array elements start at 0. ** **

The array in the above example is

int[] score = new int[]

Can be rewritten with.


The number of elements in the array is

Array variable name.length

Can be obtained at.

It is also possible to rotate an array with a for loop or an extended for statement.

・ For loop

for(int = 0; i <Array variable name.length; i++)

・ In the case of extended for statement

for(Element type Variable name (optional):Array variable name)


I wanted to learn about the ArrayList class, but it didn't seem to be mentioned in this reference book. However, I learned a lot about the basics of arrays. I thought it was easy to understand even for beginners like me. I thought that using arrays as well as variables would make the code smarter at once.

It can be turned with two, a for loop and an extended for statement, but I can use the extended for statement. I thought it would be easier to see if I removed the loop variables and subscripts.

Next, I will write about object orientation.

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