[英]Boolean and if/else statement help in Java
我试图让用户输入一个输入(显然是他们的姓名和年龄),如果他们小于10岁或大于100岁,我希望它返回到开始并再次询问他们的年龄,直到满足条件,然后继续询问用户名。 我知道该怎么做,布尔值。 我不知道该怎么做是将其实现到我的if / else语句中。 有人可以帮我吗?
public class Person {
public static void main(final String[] args) {
int age;
String name;
Scanner scan = new Scanner(System.in);
System.out.println("Enter in your age.");
age = scan.nextInt();
if ((age >= 10) && (age < 18)) {
System.out.println("So you're a kid, huh?");
} else if (age < 10) {
System.out.println("How old are you really?");
} else if ((age >= 18) && (age <= 100)) {
System.out.println("So you're an adult, huh?");
} else if (age > 100) {
System.out.println("How old are you really?");
}
@SuppressWarnings("resource")
Scanner in = new Scanner(System.in);
System.out.println("Enter in your name");
name = in.nextLine();
System.out.println("So you're " + age + " years old and your name is " + name + "?");
}
}
while
不满足条件的情况下使用while
循环:
boolean conditionMet = false;
while(!conditionMet) {
// ...
else if (age >= 18 && age <= 100) {
System.out.println("So you're an adult, huh?");
conditionMet = true; // the condition is met => exit the loop
}
// ...
}
只需在您的第一次扫描和if语句周围放置一个while循环。
boolean validAge = false;
while (!validAge) {
System.out.println("Enter in your age.");
age = scan.nextInt();
if ((age >= 10) && (age < 18)) {
System.out.println("So you're a kid, huh?");
} else if (age < 10) {
System.out.println("How old are you really?");
} else if ((age >= 18) && (age <= 100)) {
System.out.println("So you're an adult, huh?");
validAge = true;
} else if (age > 100) {
System.out.println("How old are you really?");
}
}
您需要一个循环:
boolean ageIsCorrect = false;
while (!ageIsCorrect) {
// ask age, if the age is correct, set ageIsCorrect to true
}
将其放入while循环while(年龄介于指定的critiera之间)
大概是这样的:
private static int readAndCheck() {
// read age and validate, upon failure return -1
}
public static void main(final String[] args) {
int age = -1;
while (age == -1) {
age = readAndCheck();
}
System.out.println("So you're " + age + " years old and your name is " + name + "?");
}
您应该在while
循环中这样做。 我认为它比其他答案更容易和更好:
int age = 0;
while (age<10 || age>100){
age = scan.nextInt();
}
string username = scan.next();
...
由于正在循环,因此将提示代码放入循环中。 使用布尔值退出循环
boolean goodAnswer = false; do { System.out.println("Enter in your age."); ... if ((age >= 10) && (age 100) { ... // do not set goodAnswer, because the answer was not good } } while (!goodAnswer);
实际上,您的代码需要更好地封装以检查使用期限。
使用名为isValidAge(age)
的方法返回true
或false
结果,然后可以编写:
int age = 0;
while(!isValidAge(age)){
System.out.println("Please try again! Not a valid age (for an adult)");
... read in the age using scanner...
}
一般来说,如果else()语句混乱且不能很好地扩展-从维护角度来看,它们并不总是最佳选择。
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