Java: Remove single character at given index from a string

In this post, I am going to explain how to remove single character at given index from a string. Strings in Java are immutable, so once a string is defined, you can’t change the value. Possible way is to create new string that do not contain the character at given index from original string.

 

Multiple approaches to remove single character at given index from a string.

 

Approach 1: Traverse the string character by character, form a new string by skipping the character at specific index.

 

SkipCharDemo1.java

package com.sample.app.strings;

public class SkipCharDemo1 {

	private static String skipCharAtIndex(String str, int index) {
		if (str == null || index < 0 || index > str.length()) {
			return str;
		}

		char[] chars = str.toCharArray();

		StringBuilder stringBuilder = new StringBuilder();

		for (int i = 0; i < chars.length; i++) {
			if (i == index) {
				continue;
			}
			stringBuilder.append(chars[i]);
		}

		return stringBuilder.toString();
	}

	public static void main(String args[]) {

		String str = "Hello";

		System.out.println("str -> " + str);

		for (int i = 0; i < str.length(); i++) {
			String result = skipCharAtIndex(str, i);
			System.out.println("Skipped ch at index " + i + ", result " + result);
		}

	}

}

 

Output

str -> Hello
Skipped ch at index 0, result ello
Skipped ch at index 1, result Hllo
Skipped ch at index 2, result Helo
Skipped ch at index 3, result Helo
Skipped ch at index 4, result Hell

 

Approach 2: Get StringBuilder instance from the string, remove the character at given index using deleteCharAt method.

 

SkipCharDemo2.java

 

package com.sample.app.strings;

public class SkipCharDemo2 {

	private static String skipCharAtIndex(String str, int index) {
		if (str == null || index < 0 || index > str.length()) {
			return str;
		}

		StringBuilder stringBuilder = new StringBuilder(str);
		return stringBuilder.deleteCharAt(index).toString();

	}

	public static void main(String args[]) {

		String str = "Hello";

		System.out.println("str -> " + str);

		for (int i = 0; i < str.length(); i++) {
			String result = skipCharAtIndex(str, i);
			System.out.println("Skipped ch at index " + i + ", result " + result);
		}

	}

}

 

Output

str -> Hello
Skipped ch at index 0, result ello
Skipped ch at index 1, result Hllo
Skipped ch at index 2, result Helo
Skipped ch at index 3, result Helo
Skipped ch at index 4, result Hell

Approach 3: using substring method.

 

SkipCharDemo3.java

package com.sample.app.strings;

public class SkipCharDemo3 {

	private static String skipCharAtIndex(String str, int index) {
		if (str == null || index < 0 || index > str.length()) {
			return str;
		}

		return str.substring(0, index) + str.substring(index + 1);

	}

	public static void main(String args[]) {

		String str = "Hello";

		System.out.println("str -> " + str);

		for (int i = 0; i < str.length(); i++) {
			String result = skipCharAtIndex(str, i);
			System.out.println("Skipped ch at index " + i + ", result " + result);
		}

	}

}

Output

str -> Hello
Skipped ch at index 0, result ello
Skipped ch at index 1, result Hllo
Skipped ch at index 2, result Helo
Skipped ch at index 3, result Helo
Skipped ch at index 4, result Hell

 

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