Java guessing character game

Package days06;

Demand...... , question, why use Do{}while???
Import Java.util.Scanner;
public class Repeatofgussinggame {

public static void Main (string[] args) {
/* in the main () function, you need to create a dead loop, the purpose is: if the user guessed wrong, guess the right jump (break), wrong repeatedly guess
* Note: Because the user is entering a string, we compare the array in the check method and need to convert the string to a character array
* Add the level, actually increase the difficulty, the more difficult the letter, the number of randomly generated letters added to the variable int parameter value, in making the corresponding judgment and transformation can be
*/
Scanner scan = new Scanner (system.in);
int count = 0;

char[] CHS = Genran (); Receive, Invoke
Debug output
System.out.println ("The game begins! ");
Indicates game level, default is 5
int level = 5;
do {
System.out.println ("Guessinggame> Please enter the game level (5, 7, 9)?" ");
Level = Scan.nextint ();
} while (level! = 5 && level! = 7 && level! = 9);
A string that represents a guess
char[] CHS = Genran (level);
System.out.println (CHS);
while (true) {//self-made loop, wrong always guess, right jump out of the loop,
SYSTEM.OUT.PRINTLN ("Guess! ");
String str = Scan.next (); String to receive input
Char[] Input =str.tochararray ();//Convert to character array, next call comparison method to receive results
int[] result = Check (chs,input);
if (result[1]==chs.length) {//If the position is right
int score = RESULT[0]*100-COUNT*10;
System.out.println ("Congratulations, you guessed it!") Score: "+score);
Break
}else{
System.out.println ("The position of the +result[1]+", the characters to the "+result[0]+"! ");
count++;
}
}
}
Random input
public static char[] Genran (Int. level) {
char[] CHS = new Char[level];
Char[] Letters = {' A ', ' B ', ' C ', ' D ', ' E ', ' F ', ' G ', ' H ',
' I ', ' J ', ' K ', ' L ', ' M ', ' N ',
' O ', ' P ', ' Q ', ' R ', ' S ', ' T ',
' U ', ' V ', ' W ', ' X ', ' Y ', ' Z '};
Boolean[] flags = new boolean[letters.length];//default false, switch flag
for (int i=0;i<chs.length;i++) {
int index;
do{
index = (int) (Math.random () *letters.length);
}while (flags[index]==true);
Chs[i]= Letters[index];
Flags[index] = true;
}

return CHS;
}
Contrast
public static int[] Check (char[] chs,char[] input) {
Int[] result = new Int[2];//result[1] position, result[0] character pair
for (int i=0;i<chs.length;i++) {//two-layer loop
for (int j=0;j<input.length;j++) {
if (Chs[i]==input[j]) {//Compare characters right
result[0]++;
if (i==j) {//position
result[1]++;
Break
}
}
}
}

return result;
}
}

Java guessing character game