Common string methods in Java

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Introduction

String methods help you work with text easily. They let you check, change, or find parts of words or sentences.

When you want to check if a word contains a certain letter or part.

When you need to change all letters to uppercase or lowercase.

When you want to find where a word or letter appears in a sentence.

When you want to cut out a piece of a sentence.

When you want to replace some words with others.

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Syntax

Java

string.methodName(arguments);

Replace string with your text variable or text in quotes.

Replace methodName with the name of the string method you want to use.

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Examples

line_end_arrow_notchCheck if the text contains the word "Hello".

Java

String text = "Hello World";
boolean hasHello = text.contains("Hello");

line_end_arrow_notchChange all letters in the text to uppercase.

Java

String text = "Hello World";
String upper = text.toUpperCase();

line_end_arrow_notchFind the position of the letter 'W' in the text.

Java

String text = "Hello World";
int pos = text.indexOf('W');

line_end_arrow_notchGet the part of the text starting from position 6 to the end.

Java

String text = "Hello World";
String part = text.substring(6);

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Sample Program

This program shows common string methods: checking if text contains a word, changing to uppercase, finding a letter's position, getting a part of the text, and replacing words.

Java

public class Main {
    public static void main(String[] args) {
        String message = "Java is fun!";

        // Check if message contains "fun"
        boolean containsFun = message.contains("fun");
        System.out.println("Contains 'fun': " + containsFun);

        // Convert message to uppercase
        String upperMessage = message.toUpperCase();
        System.out.println("Uppercase: " + upperMessage);

        // Find position of 'i'
        int indexI = message.indexOf('i');
        System.out.println("Position of 'i': " + indexI);

        // Get substring from position 5
        String sub = message.substring(5);
        System.out.println("Substring from 5: " + sub);

        // Replace 'fun' with 'awesome'
        String replaced = message.replace("fun", "awesome");
        System.out.println("Replaced text: " + replaced);
    }
}

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Important Notes

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String positions start at 0, so the first letter is at position 0.

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Methods like substring do not change the original string but return a new one.

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Strings in Java are case sensitive, so "Fun" and "fun" are different.

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Summary

Use string methods to easily check, change, or find parts of text.

Common methods include contains, toUpperCase, indexOf, substring, and replace.

Remember that strings do not change themselves; methods return new strings.