如何使用用户输入使健壮性发挥作用?
问题描述:
我试图在java上做一个健壮的代码,但它似乎没有工作。我在寻找的是用户输入一个输入,如果输入不是必需的输入,程序将检查输入,然后用户可以选择重新输入适当的输入,直到输入与所需的输入相匹配,或者干脆退出。这是我到目前为止。当我运行这段代码时,除非用户输入了错误的输入并且想要退出,否则一切运行良好。即使用户重新输入正确的输入或退出,while循环也会继续运行并不会停止。我该如何做这项工作?如何使用用户输入使健壮性发挥作用?
//question
System.out.println("Summer, Winter, Fall, or Spring");
System.out.print("Which season is your favarite? ");
String favSeason = in.next();
System.out.println();
//Control the inputs by converting them to Upper Case
String favSeasonInput = favSeason.toUpperCase();
//required answers of the question
String seasons = "SUMMER, WINTER, FALL, SPRING?";
String quit = "QUIT!";
boolean isSeasons = (favSeasonInput.equals(seasons.substring(0, 6)) ||
favSeasonInput.equals(seasons.substring(8, 14)) ||
favSeasonInput.equals(seasons.substring(16, 20)) ||
favSeasonInput.equals(seasons.substring(22, 28)));
boolean isQuit = favSeasonInput.equals(quit.substring(0, 4));
//inialize variables that will compute scores
int favSeasonScore = 0;
//if user enters an input otherthan seasons
while (!isSeasons){
favSeason = in.next();
if(isQuit){
System.exit(0);
}
}
//Conditions to set up scores for seasons
if(favSeasonInput.equals(seasons.substring(0, 6))){
favSeasonScore = 6;
System.out.println("Summer is " + favSeasonScore + " points");
}
else if(favSeasonInput.equals(seasons.substring(8, 14))){
favSeasonScore = 14;
System.out.println("Winter is " + favSeasonScore + " points");
}
else if(favSeasonInput.equals(seasons.substring(16, 20))){
favSeasonScore = 20;
System.out.println("Fall is " + favSeasonScore + " points");
}
else if(favSeasonInput.equals(seasons.substring(22, 28))){
favSeasonScore = 28;
System.out.println("Spring is " + favSeasonScore + " points");
}
System.out.println(favSeasonScore);
答
问题是,当您读取新输入时,您不更新布尔变量的值;你甚至不会将它读入同一个变量。
所以:
favSeason = in.next();
应该是:
favSeasonInput = in.next().toUpperCase();
isSeaons = ...;
isQuit = ...;
但是请注意,检查有效的输入的方式是可怕。这是非常低效的(抽出每个支票上的子字符串),但也非常脆弱(必须使这些索引正确),并且需要更改时必须在多个位置更新代码。
你映射一个字符串转换为整数,所以使用地图:
Map<String, Integer> seasonScores = new HashMap<>();
seasonScores.put("SPRING", 28);
// Etc.
那么你isSeason
变量变为:
isSeason = seasonScores.keySet().containsKey(favSeasonInput);
而且你的条件语句消失,成为:
seasonScore = seasonScores.get(favSeasonInput);
不包含代码作为图像粘贴在这里 – Lokesh
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