On the conversion between java array and string

1. char Array (Character Array)- > String

This can be done using the String. copyValueOf (charArray) function. 　　

Examples:

char[] arr={'a','b','c'};
String string =String.copyValueOf(arr);
System.out.println(string);          //abc

2. String Array- > String

String[] arr ={"0123","sb","12f"};
 　　 StringBuffer sb = new StringBuffer();
 
 　　 for(int i = 0;i<arr.length;i++){
 　　 sb.append(arr[i]);        //append String Do not have this method, so use the StringBuffer
 　　 }
 　　 String sb1 = sb.toString();
 　　 System.out.println(sb1);    //0123sb12f

3. java string- > Array

String str = "123abc";
 　　 char[] ar = str.toCharArray(); 　　 //char Array 
 　　 for(int i =0;i<ar.length;i++){
 　　 System.out.println(ar[i]);    //1 2 3 a b c
 　　 }
 
 　　 String[] arr = str.split("");
 　　 for(int i =0;i<arr.length;i++){ 　　 //String Array, but arr[0] Empty 
 　　 System.out.println(arr[i]);    // Empty   1 2 3 a b c
 　　 }

4. Related transformation

# # String reverse order

String s="123abc";
System.out.println(new StringBuilder(s).reverse().toString());

Strip spaces from strings

1. String. trim () trim () is to remove the first and last spaces

2. str. replace (","); Remove all spaces, including beginning and end, and copy code in the middle

String str = " hell o "; 
String str2 = str.replaceAll(" ", ""); 
System.out.println(str2); 

3. Or

replaceAll(" +",""); // Remove all spaces  

4.

str = .replaceAll("\\s*", ""); replaceAll( "\n" ,""); // To clear line breaks, etc.  

Replace most white space characters, not limited to spaces * can be removed

\ s can match any one of white space characters, such as spaces, tabs, page breaks, and so on
Common characters: space (''), page break ('\ f'), line break ('\ n'), carriage return ('\ r'), horizontal tab ('\ t'), vertical tab ('\ v')

Shaping and string conversion
String -- > Int
1) int i = Integer. parseInt ([String]); Or
i = Integer.parseInt([String],[int radix]);

2) int i = Integer.valueOf(my_str).intValue();

Int-"String
1) String s = String.valueOf(i);

2) String s = Integer.toString(i);

3) String s = "" + i;

int a=33;           
           String a1 = String.valueOf(a);      //33
           String a2 = Integer.toString(a);    //33
           String a3 = a1 +"";                   //33

           System.out.println(a1);
           System.out.println(a2);
           System.out.println(a3);
           
          String b = "101";
          String bb = "123";

           int b1 = Integer.parseInt(b+bb);                //101123    
           int b2_1 = Integer.parseInt(bb, 10);          //123
           int b2_2 = Integer.parseInt(b, 2);             // Analytic binary system   String of   5
           int b3 =  Integer.valueOf(b+bb).intValue();  //101123
           System.out.println(b3);