Replacing Substrings in a Java String

Let’s say the following is our string.

String str = "The Walking Dead!";

We want to replace the substring “Dead” with “Alive”. For that, let us use the following logic. Here, we have used a while loop and within that found the index of the substring to be replaced. In this way, one by one we have replaced the entire substring.

int beginning = 0, index = 0; StringBuffer strBuffer = new StringBuffer(); while ((index = str.indexOf(subStr1, beginning)) >= 0) {    strBuffer.append(str.substring(beginning, index));    strBuffer.append(subStr2);    beginning = index + subStr1.length(); }

The following is the complete example to replace substrings.

Example

 Live Demo

public class Demo {    public static void main(String[] args) {       String str = "The Walking Dead!";       System.out.println("String: "+str);       String subStr1 = "Dead";       String subStr2 = "Alive";       int beginning = 0, index = 0;       StringBuffer strBuffer = new StringBuffer();       while ((index = str.indexOf(subStr1, beginning)) >= 0) {          strBuffer.append(str.substring(beginning, index));          strBuffer.append(subStr2);          beginning = index + subStr1.length();       }       strBuffer.append(str.substring(beginning));       System.out.println("String after replacing substring "+subStr1+" with "+ subStr2 +" = "+strBuffer.toString());    } }

Output

String: The Walking Dead! String after replacing substring Dead with Alive = The Walking Alive!