Java preliminary cognition and use of one-dimensional arrays

Why do you use arrays
When you set too many variables of the same type, we use the array variable for ease of operation and management.
He's actually a bunch of data in an orderly place.
What is an array
1. Array declarations
Identifier
Array elements
Element subscript
Element type
element type identifier [element subscript, starting from 0]=
{array elements, array elements, array elements (array length, currently 3)};

Or
element type [element subscript, starting from 0] Identifier =
{array elements, array elements, array elements (array length, currently 3)};

Example 1:
int scores[]={1,2,3}; Array length 3
Int[] scores={1,2,3}; Array length 3
String scores[]={"ASD", "ASD", "ASD", "ASD", "ASD"}; Array length 5
String[] scores={"ASD", "ASD", "ASD", "ASD", "ASD"}; Array length 5

Example 2:
int scores[]=new int[10]; Array length 10
Int[] Scores=new int[10]; Array length 10
String Scores[]=new string[20]; Array length 20
String[] Scores=new string[20]; Array length 20

Note 1: The same array can only use one of the declarations in Example 1 and Example 2.
For example, int scores[]={1,2,3}; int scores[]=new int[10]; this is wrong.
Note 2: At the time of the declaration, the array length and the tuple can only write one.
For example, int scores[3]={1,2,3}; int scores[]=new int[3] ={1,2,3}; this is wrong.

2. Assigning values to arrays
The array's subscript must be written clearly when assigning values to the array.
For example
int scores[]=new int[10];
scores[0]=5;
scores[1]=5;
Scores[0]= scores[0]*5;
System.out.println (scores[0]+ "\ T" + scores[1]);

The result is: 25 5

A common use
Add a keyboard assignment operation with a for loop
Scanner Input=new scanner (system.in);
int scores[]=new scores[10];
int num=0;
for (int i=0;i< scores.length;i++) {//Loop 10-time assignment
Scores[i]=input.nextint (); Assigning a value with a keyboard
num+= Scores[i]; Finding the sum of array data
}
Tip 1:scores.length equals the length of the array can be used directly to determine the number of loops.

With the enhanced for loop
Scanner Input=new scanner (system.in);
int scores[]=new scores[10];
int num=0;
for (int score:scores) {//Loop 10-time assignment
num+= score; Finding the sum of array data
}
Tip: for (int score:scores) array-specific hardening for statement, which means that each loop will scores the value of the array from the subscript "0" and assign the value to score.

Common Mistakes
1. Whenever a declaration is written with an assignment and an array length, the assignment and array length must be written one.
int scores=new scores[]; Error
int scores=new scores[1]; Correct
int Scores=new scores[]{1,2,3}; Correct

2. Array out of bounds
int scores=new scores[2];
Scores[0]=1;
Scores[1]=1;
Scores[2]=1;
Scores[3]=1;
Analysis: The array declaration of two data, so should not appear scores[2] and scores[3], this is an array out of bounds.

3 syntax rules, declarations and arrays all-in-one assignment must be completed with a single statement
int scores[];
scores={1,2,3}; Error

int scores[]={1,2,3}; Correct

Java preliminary cognition and use of one-dimensional arrays