Application environment for java-loops and creation of arrays

Source: Internet
Author: User

1. Better application of three cycle structures:
1) while: "When ..." loop
2) Do...while: "Until ..." loop
Preferred Do...while when feature 1 is the same as feature 3
3) for: fixed number of cycles
2. Nested loops:
1) loop in the loop, generally multi-row multi-column when used, the outer control row, Memory control column
2) Execution rules: Outer loop Walk once, inner layer cycle all times
3) Recommendation: The fewer layers of nesting, the better, can use a layer of two layers, can use two layers without three layers
If the demand must pass through three layers of cycle can be solved, indicating that the design of a problem
4) Break can only jump out of a layer of loops
3. program = algorithm + data structure
1) algorithm: process/step for problem Solving (order, branch, Loop)
2) Data structure: to save it in a specific structure
Number How to save
Well-designed/reasonable data structures can lead to good algorithms
4. Arrays:
1) Collection of elements of the same data type
2) An array is a data type (reference type)
3) Declaration of the array:
int[] arr = new INT[10];
4) Initialization of the array:
int[] arr = new INT[3]; 0,0,0
Int[] arr = {1,4,7}; 1,4,7
int[] arr = new int[]{1,4,7}; 1,4,7
Int[] arr;
arr = {1,4,7}; Compile error, this method can only be declared at the same time initialization
arr = new int[]{1,4,7}; That's right
5) Array of access:
5.1) You can get the length of the array by (array name. length)
int[] arr = new INT[4];
System.out.println (arr.length); 4
5.2) access to elements in the array by subscript/index
Subscript starting from 0, Max to (length of array-1)
int[] arr = new INT[3];
ARR[0] = 100;
ARR[1] = 200;
ARR[2] = 300;
ARR[3] = 400; Array subscript out of bounds exception
System.out.println (Arr[arr.length-1]); Output last Element
6) Array Traversal:
int[] arr = new INT[10];
for (int i=0;i<arr.length;i++) {
Arr[i] = 100;
}
for (int i=0;i<arr.length;i++) {
System.out.println (Arr[i]);
}
for (int i=arr.length-1;i>=0;i--) {
System.out.println (Arr[i]);
}
7) Copying of arrays:
7.1) system.arraycopy (a,1,a1,0,4);
7.2) int[] A1 = arrays.copyof (a,6);
A = arrays.copyof (a,a.length+1); Expansion
8) sort the array:
8.1) Arrays.sort (arr); Ascending, high efficiency
8.2) Bubbling principle:
8.2.1) Four count three rounds
8.2.2) Each round starts with a 1th element
Every time it's the next element.
8.2.3) is out of the execution.

I am a beginner, if the update is not good, welcome the Great God pointed out, thank you!

More exciting after the update, reprinted annotated!

Application environment for java-loops and creation of arrays

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.