[英]Method in Java program won't pick up user input
我写的程序是确定一年是否是闰年。 这是一个赋值,所以我需要使用我在程序中编写的四种方法。 程序编译并运行,它在适当的位置请求用户输入,但它不会将输入带入程序。 也就是说,无论输入什么,这一年都是闰年并且循环。 我对于哪里出现错误非常困惑,因为这个程序似乎与我们给出的例子相符。
import java.util.Scanner;
public class LeapYear {
public static void main(String[] args) {
boolean repeat;
String computeanother, yes="yes";
Scanner kb=new Scanner(System.in);
int year = -1;
boolean leap;
do
{
displayInstructions();
getYear(year);
leap = isLeap(year);
displayResults(year, leap);
System.out.println("Would you like to compute another year?");
computeanother = kb.nextLine();
if(computeanother.equals(yes))
repeat=true;
else
repeat=false;
} while(repeat=true);
}
public static void displayInstructions()
{
System.out.println("This program is designed to predict whether or not a year is a leap year.");
System.out.println("When prompted please enter a positive number for the year.");
System.out.println("Once the program has run completely, it will state the year and whether it is a leap year.");
}
public static void getYear(int year)
{
Scanner kb = new Scanner(System.in);
do {
System.out.println("Please enter the year.");
year=kb.nextInt();
} while (year < 0);
}
public static boolean isLeap(int year)
{
boolean leap;
if ((year%4==0 && year%100 != 0) || year%400==0){
leap = true;
return true;
} else {
leap = false;
return false;
}
}
public static void displayResults(int year, boolean leap)
{
if (leap = true) {
System.out.println("The year " +year);
System.out.println("is a leap year.");
} else {
System.out.println("The year " +year);
System.out.println("is not a leap year.");
}
}
}
谢谢大家的帮助! 编辑后的代码如下所示:
import java.util.Scanner;
public class LeapYear{
public static void main(String[] args){
boolean repeat;
String computeanother, yes="yes";
Scanner kb=new Scanner(System.in);
int year = -1;
boolean leap;
do
{
displayInstructions();
getYear(year);
leap = isLeap(year);
displayResults(year, leap);
System.out.println("Would you like to compute another year?");
computeanother = kb.nextLine();
repeat = computeanother.equals(yes);
}while(repeat);
}
public static void displayInstructions()
{
System.out.println("This program is designed to predict whether or not a year is a leap year.");
System.out.println("When prompted please enter a positive number for the year.");
System.out.println("Once the program has run completely, it will state the year and whether it is a leap year.");
}
public static int getYear(int year)
{
Scanner kb = new Scanner(System.in);
do{
System.out.println("Please enter the year.");
year=kb.nextInt();
}while (year < 0);
return year;
}
public static boolean isLeap(int year)
{
boolean leap;
year = getYear(year);
if ((year%4==0 && year%100 != 0) || year%400==0){
leap = true;
return true;}
else{
leap = false;
return false;}
}
public static int displayResults(int year, boolean leap)
{
year = getYear(year);
if (leap == true){
System.out.println("The year " +year);
System.out.println("is a leap year.");}
else{
System.out.println("The year " +year);
System.out.println("is not a leap year.");}
return year;
}
}
while(repeat=true);
在while循环中应该是:
while(repeat == true);
要么
while(repeat);
除了每个人都注意到这一点,你可以注意到你犯了这个错误两次:
if (leap = true) {
应该:
if (leap == true) {
要么
if (leap) {
您还可以缩短代码:
do{
displayInstructions();
getYear(year);
leap = isLeap(year);
displayResults(year, leap);
System.out.println("Would you like to compute another year?");
computeanother = kb.nextLine();
repeat = computeanother.equals(yes) //this line makes code shorter
} while(repeat);
确实,总是避免代码冗余,就像这个着名的模式:
if(expression) return true; else return false;
那就变成了: return expression;
改变这个:
while(repeat=true);
至
while(repeat==true);
要么
while(repeat);
这里while(repeat=true);
你正在分配一个值,而不是比较。 while(repeat==true);
或者while(repeat);
这将比较价值。 这样测试总是更好while(repeat);
而不是显而易见的while(repeat==true);
。 我希望它有所帮助。
并且你没有获得year
价值-1因为,你从这个方法返回getYear(year);
但忽略了价值。 将其更改为:
year = getYear(year);
这应该工作。
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