How can I remove a substring from a given String?

Is there an easy way to remove substring from a given String in Java?

Example: "Hello World!", removing "o" → "Hell Wrld!"

You could easily use String.replace():

String helloWorld = "Hello World!";
String hellWrld = helloWorld.replace("o","");

You can use StringBuffer

StringBuffer text = new StringBuffer("Hello World");
text.replace( StartIndex ,EndIndex ,String);

Check out Apache StringUtils:

> - static String replace(String text, String searchString, String replacement) Replaces all occurrences of a String within another > String. > - static String replace(String text, String searchString, String replacement, int max) Replaces a String with another String inside a > larger String, for the first max values of the search String. > - static String replaceChars(String str, char searchChar, char replaceChar) Replaces all occurrences of a character in a String with > another. > - static String replaceChars(String str, String searchChars, String replaceChars) Replaces multiple characters in a String in one go. > - static String replaceEach(String text, String[] searchList, String[] replacementList) Replaces all occurrences of Strings within > another String. > - static String replaceEachRepeatedly(String text, String[] searchList, String[] replacementList) Replaces all occurrences of > Strings within another String. > - static String replaceOnce(String text, String searchString, String replacement) Replaces a String with another String inside a > larger String, once. > - static String replacePattern(String source, String regex, String replacement) Replaces each substring of the source String that > matches the given regular expression with the given replacement using > the Pattern.DOTALL option.

replace('regex', 'replacement');
replaceAll('regex', 'replacement');

In your example,

String hi = "Hello World!"
String no_o = hi.replaceAll("o", "");

This works good for me.

String hi = "Hello World!"
String no_o = hi.replaceAll("o", "");

or you can use

String no_o = hi.replace("o", "");

You should have to look at StringBuilder/StringBuffer which allow you to delete, insert, replace char(s) at specified offset.

You can use Substring also for replacing with existing string:

var str = "abc awwwa";
var Index = str.indexOf('awwwa');
str = str.substring(0, Index);

If you know the start and end index you may use this

string = string.substring(0, start_index) + string.substring(end_index, string.length());

replaceAll(String regex, String replacement)

Above method will help to get the answer.

String check = "Hello World";
check = check.replaceAll("o","");

You can also use guava's CharMatcher.removeFrom function.

Example:

 String s = CharMatcher.is('a').removeFrom("bazaar");

private static void replaceChar() {
    String str = "hello world";
    final String[] res = Arrays.stream(str.split(""))
            .filter(s -> !s.equalsIgnoreCase("o"))
            .toArray(String[]::new);
    System.out.println(String.join("", res));
}

In case you have some complicated logic to filter the char, just another way instead of replace().

Here is the implementation to delete all the substrings from the given string

public static String deleteAll(String str, String pattern)
{
	for(int index = isSubstring(str, pattern); index != -1; index = isSubstring(str, pattern))
		str = deleteSubstring(str, pattern, index);

	return str;
}

public static String deleteSubstring(String str, String pattern, int index)
{
    int start_index = index;
    int end_index = start_index + pattern.length() - 1;
    int dest_index = 0;
    char[] result = new char[str.length()];


    for(int i = 0; i< str.length() - 1; i++)
        if(i < start_index || i > end_index)
            result[dest_index++] = str.charAt(i);

    return new String(result, 0, dest_index + 1);
}

The implementation of isSubstring() method is here

You can use

String helloWorld = "Hello World";
String target = "e";
String replacement = "";
String replacedString = helloWorld.replace(target, replacement);

The answer is = Hllo World

or you can use regex

String original = "Java is one of best languages. OOP can be used in Java";
String regexTarget = "\\bJava\\b";
String replacedWord = original.replaceAll(regexTarget, "Python");

The answer is = Python is one of best languages. OOP can be used in Python

In addition to @DwB answer, you can also use StringUtils remove:

String hello = "hello world";
String hellYeah = StringUtils.remove(hello, "o");

or removeIgnoreCase:

String hello = "hellO world";
String hellYeah = StringUtils.remove(hello, "o");