输入字符串选择

Question

所以我现在是Java的初学者，我一直在玩弄字符串。现在我想给用户一个选择输入和"Enter a or b: "给出了基于要么"a"或"b"

代码中的输出：

int a = 18; 
int b = 22; 

Scanner user_input = new Scanner (System.in); 

String first_name; 
System.out.println("Enter your first name: "); 
first_name = user_input.next(); 

String last_name; 
System.out.println("Enter your last name: "); 
last_name = user_input.next(); 

String full_name; 
full_name = first_name + " " + last_name; 
System.out.println("You are: " + full_name); 

String age; 
System.out.println("Enter a or b: "); 
age = user_input.next(); 

String age_a; 
System.out.println("Your age is 18"); 
age = user_input(a); 

我也在想，也许功能可以使用，如：

if(user_input = a) 
{ 
    System.out.println("Your age is 18."); 
} 

Answer 1

一旦你有age你必须检查的价值，但因为它是一个String你MUST使用String.equals()

if (age.equals("a")) 
    System.out.println("Your age is 18"); 
else 
    System.out.println("Your age is 22"); 

如果您要检查的答案是ONLYa或b使用while循环重复问题，直到答案是期望：

String age; 
while (!age.equals("a") || !age.equals("b")) { 
    // ask for age 
} 

Answer 2

你可以，如果用"string".equals("other_string")使用以比较它们：

int a = 18; 
int b = 22; 

Scanner user_input = new Scanner (System.in); 

System.out.println("Enter your first name: "); 
String first_name = user_input.next(); 

System.out.println("Enter your last name: "); 
String last_name = user_input.next(); 

String full_name = first_name + " " + last_name; 
System.out.println("You are: " + full_name); 

System.out.println("Enter a or b: "); 
String ageChoice = user_input.next(); 

String age = null; 
if(ageChoice.equals("a")){ 
    age = String.valueOf(a); 
} 
else if(ageChoice.equals("b")){ 
    age = String.valueOf(b); 
} 
System.out.println("Your age is: " + age);