[英]Why does this for loop run infinitely after recieving input? (Java)
好的,因此此代碼要求用戶輸入姓名,年份和性別,並顯示所選年份的姓名排名。 它每年從URL中讀取數據並將其放入地圖中。 然后將這些地圖放入數組中,最后將排名顯示給用戶。 進入while循環后,我的程序永遠無法完成運行。 這是代碼:
public static void main(String[] args) throws MalformedURLException, IOException {
Scanner input = new Scanner(System.in);
Map[] boyArray = new Map[10];
Map[] girlArray = new Map[10];
System.out.print("Enter year (between 2001 and 2010): ");
String year = input.nextLine();
System.out.print("Enter gender (M or F): ");
String gender = input.nextLine();
System.out.print("Enter name: ");
String name = input.nextLine();
for (int i = 0; i < 10; i++) {
Map<String, String> boys = new HashMap<>();
Map<String, String> girls = new HashMap<>();
try {
java.net.URL url = new java.net.URL("http://www.cs.armstrong.edu/liang/data/babynamesranking"+ year + ".txt");
Scanner urlInput = new Scanner(url.openStream());
while (urlInput.hasNext()) {
String rank = input.next();
boys.put(urlInput.next(), rank);
urlInput.next();
girls.put(input.next(), rank);
urlInput.next();
}
}
catch (IOException ex) {
}
boyArray[i] = boys;
girlArray[i] = girls;
}
if (gender.charAt(0) == 'M') {
System.out.println("The name " + name + " was ranked " + boyArray[Integer.parseInt(year) - 2001].get(name) + " in " + year);
} else {
System.out.println("The name " + name + " was ranked " + girlArray[Integer.parseInt(year) - 2001].get(name) + " in " + year);
}
}
}
就像@uthark已經指出的那樣,您的程序正在等待輸入,因為在while
循環中,您正在等待System.in
輸入,該行的行為String rank = input.next();
(以及命令行girls.put(input.next(), rank);
)。 您可能打算編寫String rank = urlInput.next();
和girls.put(urlInput.next(), rank);
而是使排名和女孩名來自http://www.cs.armstrong.edu/liang/data/babynamesranking
YYYY .txt
。
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