Wie gehe ich zu einer Zeile, wenn ein falscher Wert eingegeben wird?

Question

Ich habe versucht, dies herauszufinden: wie Sie sicherstellen, dass das Programm weiterläuft, bis der richtige Wert eingegeben und nicht beendet wird, wenn ein falscher Wert eingegeben wird.

Code:

package class3; 

import java.util.Scanner; 

public class dayName { 

public static void main(String args[]){ 

    Scanner input = new Scanner(System.in); 
    System.out.println("\nEnter any of the following values from 0 to 7 and \nI'll tell you the corresponding day.\n"); 
    int day = input.nextInt(); 

    switch (day){ 

    case 0: day = 0; 
    if (day == 0) 
     System.out.println("\nThat would be Sunday!\n"); 
     break; 
    case 1: day = 1; 
    if (day == 1) 
     System.out.println("\nThat would be Monday!\n"); 
     break; 
    case 2: day = 2; 
    if (day == 2) 
     System.out.println("\nThat would be Tuesday!\n"); 
     break; 
    case 3: day = 3; 
    if (day == 3) 
     System.out.println("\nThat would be Wednesday!\n"); 
     break; 
    case 4: day = 4; 
    if (day == 4) 
     System.out.println("\nThat would be Thursday!\n"); 
     break; 
    case 5: day = 5; 
    if (day == 5) 
     System.out.println("\nThat would be Friday!\n"); 
     break; 
    case 6: day = 6; 
    if (day == 6) 
     System.out.println("\nThat would be Saturday!\n"); 
     break; 
    default: if(day < 0 && day > 6); 
     System.out.println("\nThere's no day as such!\n"); 
     System.exit(0); 

    } 
} 

} 

Dank.

Answer 1

es in einer Schleife einfügen:

do { 
    int day = input.nextInt(); 

    switch (day){ 

    case 0: day = 0; 
    if (day == 0) 
    System.out.println("\nThat would be Sunday!\n"); 
    break; 
    case 1: day = 1; 
    if (day == 1) 
    System.out.println("\nThat would be Monday!\n"); 
    break; 
case 2: day = 2; 
    if (day == 2) 
    System.out.println("\nThat would be Tuesday!\n"); 
    break; 
    case 3: day = 3; 
    if (day == 3) 
    System.out.println("\nThat would be Wednesday!\n"); 
    break; 
    case 4: day = 4; 
    if (day == 4) 
    System.out.println("\nThat would be Thursday!\n"); 
    break; 
    case 5: day = 5; 
    if (day == 5) 
    System.out.println("\nThat would be Friday!\n"); 
    break; 
    case 6: day = 6; 
    if (day == 6) 
    System.out.println("\nThat would be Saturday!\n"); 
    break; 
    default: if(day < 0 || day > 6); 
    System.out.println("\nThere's no day as such, insert another one!\n"); 
    day = -1; 
    break; 

} 
while (day != -1) 

Answer 2

boolean isValid = false; 
do 
{ 
    final int day = scanner.nextInt(); 
    if (day >= 0 && day <= 6) 
    { 
     isValid = true; 
    } 
    else 
    { 
     switch (day) 
     { 
      case 0: 
       System.out.println("Sunday"); 
       break; 
      case 1: 
       System.out.println("Monday"); 
       break; 
      case 2: 
       System.out.println("Tuesday"); 
       break; 
      case 3: 
       System.out.println("Wednesday"); 
       break; 
      case 4: 
       System.out.println("Thursday"); 
       break; 
      case 5: 
       System.out.println("Friday"); 
       break; 
      case 6: 
       System.out.println("Saturday"); 
       break; 
      default: 
       System.out.println("Incorrect"); 
     } 
    } 
} while (!isValid); 

Dieser Code funktioniert für mich. Sie müssen etwas falsch gemacht haben, wenn es nicht für Sie arbeitet.