[java] 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!"

replaceAll(String regex, String replacement)

Above method will help to get the answer.

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

You can use Substring also for replacing with existing string:

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

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.

You can use StringBuffer

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

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

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().

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

Example:

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

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

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", "");

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

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

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

In your example,

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