예 :숫자 문자열에서 한자리 숫자를 추출하려면 어떻게합니까?
String number = "123456789";
은 어떻게 INT 타입 변수에 그 자체로 마지막 숫자로 두 번째를 저장합니까? 자세한
:
for (int i = number.length()-2; i>-1; i-=2)
int x = (Extract the number) at i;
내가 이걸 어떻게해야합니까? 여기
코드입니다 :package creditcard;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.IOException;
public class Card {
//Declarations
private String cardNumber;
private boolean test = false;
private String cardType = "Unknown";
public Card(){
cardNumber = "0";
}//end Default Constructor
public Card(String input){
cardNumber = input;
}//end Constructor
//
public void typeMatcher(){
if (cardNumber.startsWith("37"))
cardType = "American Express";
if (cardNumber.startsWith("4"))
cardType = "Visa";
if (cardNumber.startsWith("5"))
cardType = "Mastercard";
if (cardNumber.startsWith("6"))
cardType = "Discover";
}//end typeMatcher
// Returns true if card number is Valid.
public boolean isValid(String cardNumber){
if (cardNumber.length() > 12 && cardNumber.length() < 17)
if((sumOfDoubleEvenPlace(cardNumber)+sumOfOddPlace(cardNumber))/10==0)
test = true;
return test;
}//end isValid
// Get result from Step 2.
public int sumOfDoubleEvenPlace(String cardNumber){
int sum = 0;
int num = 0;
for (int i = cardNumber.length()-2; i>-1; i-=2){
num = Integer.parseInt(cardNumber.substring(i,i+1));
if (num<10)
sum+=(num*2);
else
sum+=getDigit(num);
}//end for
System.out.println(sum);
return sum;
}//end SumOfDoubleEvenPlace
// Return this number if it is a single digit
// Otherwise return the sum of the two digits.
public int getDigit (int num){
int no1 = num/10;
int no2 = num%10;
return no1+no2;
}//end getDigit
// Returns sum of odd place digits in number.
public int sumOfOddPlace(String cardNumber){
int sum = 0;
for (int i = cardNumber.length()-1; i>-1; i-=2)
sum += Integer.parseInt(cardNumber.substring(i,i));
System.out.println(sum);
return sum;
}//end sumOfOddPlace
public void writeToFile(){
try{
FileWriter fw = new FileWriter("G:\\Output.txt",true);
BufferedWriter bw = new BufferedWriter(fw);
if (isValid(cardNumber)){
bw.write(cardNumber+" is a valid "+cardType+" card.");
bw.newLine();
}//end if
else{
bw.write(cardNumber+" is an invalid "+cardType+" card.");
bw.newLine();
}//end else
bw.close();
System.out.println("Success");
}//end try
catch(IOException ioe){
ioe.printStackTrace();
}//end catch
}//end outputToFile
}//end Card
목표는 신용 카드 번호는 (학교 프로젝트)
여기 자바 질문에 답하는 것이 힘듭니다. 저학년 저크 레벨이 너무 높습니다. – Pointy
아멘. 때로는 아프다. – EboMike
'0'문자의 숫자 값은 48 iirc입니다. 그것은 아마도 downvote가 어디에서 왔는지입니다. –