ways to reverse string in java

reversing a string by converting to array in java

/**
 * @author lautturi.com 
 * Java example: reverse a string in java
 */

import java.util.*;

public class Lautturi {
	public static void main(String[] args) {
		String str = "hello lautturi.com java world!";
		char arr[] = str.toCharArray();
		for(int i=0;i<arr.length/2;i++) {
			char temp = arr[i];
			arr[i]=arr[arr.length-i-1];
			arr[arr.length-i-1] = temp;
		}
		String newString = new String(arr);
		System.out.println(newString);
	}
}

output:

!dlrow avaj moc.iruttual olleh

reversing a string using StringBuilder in java

/**
 * @author lautturi.com 
 * Java example: reverse a string in java
 */

import java.util.*;

public class Lautturi {
	public static void main(String[] args) {
		String str = "hello lautturi.com java world!";
		StringBuilder sb = new StringBuilder();
		sb.append(str);
		sb.reverse();
		String newString = sb.toString();
		System.out.println(newString);
	}
}

output:

!dlrow avaj moc.iruttual olleh

reverse a string in java using list collections

/**
 * @author lautturi.com 
 * Java example: reverse a string in java
 */

import java.util.*;

public class Lautturi {
	public static void main(String[] args) {
		String str = "hello lautturi.com java world!";
		String[] arr = str.split("");
		List<String> list = Arrays.asList(arr);
		Collections.reverse(list);
		String newString = String.join("", arr);
		System.out.println(newString);
		String newString2 = String.join("", list);
		System.out.println(newString2);
	}
}

iterate over characters in string (not recommended)

/**
 * @author lautturi.com 
 * Java example:  reverse string in java
 */

import java.util.*;

public class Lautturi {
	public static void main(String[] args) {
		String str = "hello lautturi.com java world!";
		String newString = "";
		for (int i = str.length() - 1; i >= 0; i--) {
			newString += str.charAt(i);  // or str.substring(i, i+1);
		}
		System.out.println(newString);
	}
}

output:

!dlrow avaj moc.iruttual olleh