Java--array

1.basic use of arrays

(1) the function of the array

A set of numbers of the same data type

An array is also a variable, a string of contiguous spaces in memory

(2) Basic concepts of arrays

Elements: (data stored in an Array)

data type: (type of data,int,double,string , etc.)

subscript (starting from 0 to array . length-1 End)

the length of the array (array . Length)

(3) array Use steps

Declaring an array

int[] num;

Int num[];

Allocate space

Num=new int[9];

Assign Value

int[] num={5,8,9};

Working with Data

Sum of Steps:

int[] num=new int[]{5,8,9};

(4) duration:

(1.1) method one: Traditional for

(1.2) method Two:

Enhanced for(foreach)

for (int score:scores) {

sum+=score;

}

(can only be used in an array of well-assigned values, assigning values obtained in scores to score)

the purpose is to iterate through each value in the Array. The traversal means: every value goes through it again.

If you use Scanner words, The following wording:

for (int I=0;i<scores.length;i++) {

System. Out. println ("please enter" + (i+1) + "gate score");

Scores[i]=input.nextint ();

}

for (int score:scores) {

sum+=score;

}

(5) Common Errors:

　　　　

correction: such as: (1)int score""={60,80,90,70,85};

(2)int score""=new int"" {60,80,90,70,85 };

(6)Example Explanation:

　　　　

　　　　

and a for is used toiterate over it so that each number in the array is compared to the value entered

(7) Basic use of arrays

declaring an array (type [] array name or type array name [])

Allocate Space ( what is the value of the length of the declared array )

(array Name = new data type [X]; )

Attention:

created by New , typically reference data types

Assign value (num0= ; num1= ; )

Process data (process data according to specific requirements)

Variable:

1. Basic data type: (stored in stack memory; no METHOD)

int ,float,double, char, boolean

2, Reference Data type: (stored in the heap memory, you can point out methods and properties)String, Array

3. Basic data types and reference data types:

The memory distribution is different,

different on Use (reference data type can . out some methods and properties)

Java--array