Non-professional Code Nong Java Learning note 6java Tools class and algorithm-string

Continued "Non-professional code Nong Java Learning Note 5 Java Tools classes and Algorithms"

V. String of strings

String and character differences: string double quotation marks "n", character enclosed in single quotation marks, denotes a symbol ' \ n '

The main methods and properties of 1.string

Class	Method or Property	Note
Define String	Stirng s=new String ("value"), String s= "value"
Property	The length of the string.length:string is byte
Method Startswith,endswith	S.startwith ("value")-starts with a value, S.endswith ("")-end
Method: Find IndexOf	S.indexof ("value")-Find where the value first appears (0 start)
	S.lastindexof ("")-the location where the last occurrence of the value was found
	(char) s.charat (int index)-Find out the characters of the first few
	(last) IndexOf (Str,strindex), find this character is the same as the first str ...
Method: Compare	Bool s.equals (S0), S.compareto (S2), result 1,0,-1 (C #)
Method: Connect Concat	S.concat (S0), equivalent to +
StringBuffer (C#stringbuilder)	After instantiation: Append ("value") is added; Insert (n, "value"); Setchatat (n, ' value ')-N is index

2.javaapplication command line parameters (input) Usercomlparameter.java

public class Usercomlparameter

{

public static void Main (String args[])//args[] array, you can lose an indefinite number of String

{

int a1,a2,a3;

if (args.length<2)

{

System.out.println ("Run this program should provide two command line parameters");

System.exit (0);

}

A1=integer.parseint (Args[0]);//define a good type for easy calculation

A2=integer.parseint (Args[1]);

A3=A1*A2;

The product of System.out.println (a1+ "and" +a2+ "equals" +a3 ");

}

}

Command line: Javac Usercomlparameter.java then Java usercomlparameter 52-4, where two parameters are entered for the specific values

Vi. recursion (call yourself, grow up)

Long factorical (int n)

{

If (N==1)

Return 1;//Recursive header

Else

Return n.factorical (n-1);//Recursive call itself

}

Can be used to sequence the law of this type, step-by, limit the scope of the recursive head, and then layered, and finally careful not infinite loop

Seven, sort (by understanding, with C # almost, here only write the principle)

1. Bubble-22 contrast, the order of large, reverse take small, and then with the back of the ratio; traverse the n-1 wheel

2. Select Sort-Select the smallest or largest from the target, and put in the sorting sequence; Repeat work is always selected.

3. Insert Sort: Select, here is a sequence based on the virtual position to draw a number of a sequence

4. System sort function: (void) sort ("");

Eight, find

1. Sequential Lookup: Traversal

2. On the sub-search-the middle number, divided into two columns, greater than alive less than, exclude a column ... Keep going.

3. System Lookup: Arrays's BinarySearch ([array],key key value)

Nine, the list of ten, queue Xi., stack 12, fork Tree

(slightly, have time to take a look carefully, perhaps will use, usually the project less use, someone see feel important say a sound, I look again)

Non-professional Code Nong Java Learning note 6java Tools class and algorithm-string