如何在字符串前後打印字符串然後將新字符串添加到舊字符串中？

Question

我試圖做一個程序，可以前後串然後要求用戶添加一個新的字符串並打印新的字符串，用戶喜歡這裏是一個樣本的位置後讀取字符串：

Enter a long string: The quick brown fox jumped over the lazy dog 

Enter a substring: jumped 

Length of your string: 44 

Length of your substring: 6 

Starting position of your substring in string: 20 

String before your substring: The quick brown fox 

String after your substring: over the lazy dog 

Enter a position between 0 and 43: 18 

The character at position 18 is x 

Enter a replacement string: leaped 

Your new string is: The quick brown fox leaped over the lazy dog 

這裏是我的代碼，我在做什麼：

import java.util.Scanner; 

public class Project02 { 

    public static void main(String[] args) { 

     Scanner name = new Scanner (System.in); 

     System.out.println("Enter a long string: "); 
     String username = name.nextLine(); 
     System.out.println("Enter a substring: "); 
     String subname = name.nextLine(); 
     System.out.println("Length of your string: "+ username.length()); 
     System.out.println("Length of your substring: " + subname.length()); 
     System.out.println("Starting position of your substring in string: "+ username.indexOf(subname)); 

     System.out.println("Enter a replacement string: "); 
     String newname = name.nextLine(); 
     System.out.println("Your new string is: "+); 


    } 

} 

Answer 1

輸入的字符串前面的字符串應該是username.substring(0, username.indexOf(subname)，之後的字符串應該是username.substring(username.indexOf(subname) + subname.length)。然後在這兩個子串之間打印新的字符串。

Answer 2

所以：

int index = text.indexOf(substring); 
String left = text.substring(0, index); 
String right = text.substring(index + substring.length()); 
String replacement = name.nextLine(); 
String newText = left + replacement + right;