格式化輸出方法

Question

我對顯示數組方法有疑問。我想不出如何使它格式化這個：

Credit Card # 4: 
8908 9014 8812 1331 

我需要做的是爲每個數組元素只是調用顯示方法和傳遞數組的索引在字符串中的標籤，我無法弄清楚如何做到這一點，我想這一點，但它是錯誤的：

System.out.println(display("Credit Card # %d", cred1[i])); 

任何人都可以請提出一個方法來做到這一點？

package homework4; 
import java.util.Scanner; 
public class Prog4 { 
static Scanner scanner = new Scanner(System.in); 
public static void main(String[] args) 
{ CreditCardNumber[] cred1; 
    CreditCardNumber cred2 = getInput(); 
    Display("The complete number from your input:", cred2); 
    cred1 = getInputArray(); 
    DisplayArray(cred1); 
    TryAnother(); 
} 

public static CreditCardNumber getInput() { 
    String ID; 
    String accNum; 
    CreditCardNumber tempCred;  
    System.out.printf("Please enter issuer ID:"); 
    ID = scanner.next(); 
    System.out.printf("Please enter account number:"); 
    accNum = scanner.next(); 
    tempCred = new CreditCardNumber(ID, accNum); 

    return tempCred; 
} 
public static void Display(String ch, CreditCardNumber cred2) 
{ 

    System.out.println(ch); 
    System.out.println(cred2.toString().replaceAll(".{4}", "$0 "));  
} 

public static CreditCardNumber[] getInputArray() 
{ 
    CreditCardNumber[] tempArray; 
    String tempID; 
    int size;  
    System.out.printf("Please enter size of the aray:"); 
    size = scanner.nextInt(); 
    if(size < 1) 
    { 
     size = 1; 
    } 
    tempArray = new CreditCardNumber[size]; 
    System.out.printf("Please enter issuer ID:"); 
    tempID = scanner.next(); 
    System.out.print(tempArray.length); 
    for(int i = 0; i < tempArray.length; i++) 
    { 
     tempArray[i] = new CreditCardNumber(); 
     tempArray[i].CreateCred(tempID); 
    } 

    return tempArray; 
} 

public static void DisplayArray(CreditCardNumber[] cred1) 
{ 
    for(int i = 0; i< cred1.length; i++) 
    { 
     System.out.println(display("Credit Card # %d", cred1[i])); 
    } 
} 

public static boolean TryAnother() 
{ 
    String s; 
    System.out.printf("Get more credit card numbers? (n for no):"); 
    s = scanner.next(); 
    if(s.charAt(0) != 'N' && s.charAt(0) != 'n') 
    { 
     return true; 
    } 
    return false; 
} 
} 

Answer 1

聽起來像所有你需要的是一個新的行字符。例如。

System.out.println("Credit Card # " + cred1[i] + "\n" + cred2.toString()); 

新行字符「\ n」會將輸出放到它自己的行上。

Answer 2

這樣做：

System.out.format("Credit Card # %d:\n%s", i, cred1[i].toString());