JAVA中的条件逻辑和字符串运算

Question

我是全新的，完全迷路了。 我正在寻找可以向我解释如何执行此操作的教程或资源：

为每个展开的缩写输出一条消息，然后输出展开的行。

例如

Enter text: IDK how that happened. TTYL. 
You entered: IDK how that happened. TTYL.

Replaced "IDK" with "I don't know".
Replaced "TTYL" with "talk to you later".

Expanded: I don't know how that happened. talk to you later.

我知道如何做userText.replace部分以将IDK更改为I don't know ，但我不知道如何设置它以搜索IDK的字符串

Answer 1

您可以使用String.indexOf()查找给定字符串的第一个实例：

String enteredText = "IDK how that happened. TTYL.";
int pos = enteredText.indexOf("IDK");    // pos now contains 0
pos = enteredText.indexOf("TTYL");    // pos now contains 23

如果indexOf()找不到字符串，则返回-1。

一旦知道已经找到一个值（通过测试pos != -1) ，执行替换并输出消息。

Answer 2

使用String.indexOf()检查输入字符串中是否存在每个缩写，如果存在，则用replaceAll()修改该字符串：

import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter text: ");
    String text = scanner.nextLine();
    System.out.println("You entered: " + text); 
    if(text.indexOf("IDK") != -1) {
      System.out.println("Replaced \"IDK\" with \"I don't know\""); 
      text = text.replaceAll("IDK", "I don't know");
    }
    if(text.indexOf("TTYL") != -1) {
      System.out.println("Replaced \"TTYL\" with \"talk to you later\""); 
      text = text.replaceAll("TTYL", "talk to you later");
    }
    System.out.println("Expanded: " + text);
  }
}

输出：

Enter text:  IDK how that happened. TTYL.
You entered: IDK how that happened. TTYL.
Replaced "IDK" with "I don't know"
Replaced "TTYL" with "talk to you later"
Expanded: I don't know how that happened. talk to you later.

在这里尝试！

注意：上面的实现不处理该问题的任何大写输入，我建议您研究toLowerCase()或toUppperCase() 。