How to use big data array
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1.5.1 Array definition and element access
An array is a container that stores a specified data type
Note:
1. An array is a container of fixed length. Once the instantiation is completed, the length cannot be modified.
The noun explains:
1. Array length: refers to the capacity of the container, indicating how much data can be stored in the array
two。 Element: refers to the data stored in the array
3. Subscript: an index of the position of an element in an array
4. Traversal array: get each element of the array in turn
* * element access to array * *
Accessed by subscript, the subscript of the elements in the array starts at 0
The subscript of the element in the array: [0, array .length-1]
* * Note: * *
When accessing the elements in the array, pay attention to the range of the subscript, do not cross the boundary!
Traverse the array:
1. Use looping through the subscript
```java
Int [] array = {1,2,3}
For (int index = 0; index < array.length; index++) {
System.out.println (Array index)
}
`
two。 Use enhanced for loops
```java
Int [] array = {1,2,3}
For (int ele: array) {
System.out.println (ele)
}
`
Memory Analysis of 1.5.2 Array
1.5.3 Common operation of array
1.5.4 array sorting
* * Select sort * *
Fix a subscript, and then compare the elements corresponding to this subscript with the elements of each subscript that follow.
```java
Int [] array = {1,3,5,7,9,0,8,6,4,2}
For (int index = 0; index < array.length-1; index++) {
For (int compare = index + 1; compare < array.length; compare++) {
If (array [index] < array [compare]) {
Int temp = array [index]
Array [index] = array [compare]
Array [compare] = temp
}
}
}
`
* * Bubble sort * *
Compare two adjacent elements in an array in turn
```java
Int [] array = {1,3,5,7,9,0,8,6,4,2}
For (int I = 0; I < array.length; iTunes +) {
For (int j = 0; j < array.length-1-I; jacks +) {
If (array [j] < array [j + 1]) {
Int temp = array [j]
Array [j] = array [j + 1]
Array [j + 1] = temp
}
}
}
`
1.5.5 Array element lookup
Query the subscript that appears for the specified element from an array
1. Sequential search
two。 Binary search
1.5.6 two-dimensional array
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