我的代碼從用戶那里獲取輸入，如果有兩個"bread"子字符串，則打印它們之間的字符串。例如，"breadjavabread"輸出"java"。但是，當我的代碼只有一個"bread"字符串時，會彈出一個錯誤。例如，"usjdbbreaddudub"。我該如何解決這個問題？String cheese = "no bread";String bread = "bread";for (int i = 0; i < s.length() - 5; i++){ String m = s.substring(i, i + 5); if (m.equals(bread)) { cheese = s.substring(s.indexOf(bread) + bread.length(), s.lastIndexOf(bread)); }}System.out.print(cheese);
1 回答
慕哥9229398
TA貢獻1877條經驗 獲得超6個贊
有很多方法可以解決這個問題。這是其中的3個
比較indexOf和lastIndexOf
String cheese;
String bread = "bread";
int firstIndex = s.indexOf(bread);
int lastIndex = s.lastIndexOf(bread);
if (firstIndex == -1) {
cheese = "no bread";
} else if (lastIndex == firstIndex) {
cheese = "only one bread";
}
cheese = s.substring(firstIndex + bread.length(), lastIndex);
System.out.print(cheese);
常用表達：
Matcher m = Pattern.compile("bread(.+?)bread").matcher(s);
if (m.find()) {
System.out.println(m.group(1));
} else {
System.out.println("Not enough bread");
}
分裂：
String[] parts = s.split("bread");
if (parts.length == 3) {
System.out.println(parts[1]);
} else {
System.out.println("Not enough or too much bread");
}
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