在这篇文章中，我们会讨论10种用Java反转字符串的方法，通过10个Java程序反转字符串。例如，把字符串“javaguides” 反转为 “sediugavaj”。

1. 使用 + (String连接) 操作符

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseWithStringConcat {

public static void main(String[] args) {

ReverseWithStringConcat concat = new ReverseWithStringConcat();

concat.reverseWithStringConcat("javaguides");

}

private String reverseWithStringConcat(String input) {

String output = new String();

for (int i = (input.length() - 1); i >= 0; i--) {

output += (input.charAt(i));

}

display(input, output);

return output;

}

private void display(String input, String output) {

System.out.println(" input string :: " + input);

System.out.println(" output string :: " + output);

}

}

输出：

input string :: javaguides

output string :: sediugavaj

2. 使用 StringBuilder

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseWithStringBuilderBuiltinMethod {

public static void main(String[] args) {

ReverseWithStringBuilderBuiltinMethod builtinMethod = new ReverseWithStringBuilderBuiltinMethod();

builtinMethod.reverseWithStringBuilderBuiltinMethod("javaguides");

}

public String reverseWithStringBuilderBuiltinMethod(String string) {

final StringBuilder builder = new StringBuilder(string);

display(string, builder.reverse().toString());

return builder.reverse().toString();

}

private void display(String input, String output) {

System.out.println(" input string :: " + input);

System.out.println(" output string :: " + output);

}

}

输出：

input string :: javaguides

output string :: sediugavaj

3. 使用 String charAt 方法

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseWithStringChatAt{

public static void main(String[] args) {

ReverseWithStringChatAt reverseWithStringBuilder = new ReverseWithStringChatAt();

reverseWithStringBuilder.reverseWithStringBuilder("javaguides");

}

public String reverseWithStringChatAt(String string) {

final StringBuilder builder = new StringBuilder();

for (int i = (string.length() - 1); i >= 0; i--) {

builder.append(string.charAt(i));

}

display(string, builder.toString());

return builder.toString();

}

private void display(String input, String output) {

System.out.println(" input string :: " + input);

System.out.println(" output string :: " + output);

}

}

输出：

input string :: javaguides

output string :: sediugavaj

4. 通过交换字符反转

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseStringWithSwaps {

public static void main(String[] args) {

ReverseStringWithSwaps stringWithSwaps = new ReverseStringWithSwaps();

stringWithSwaps.reverseWithSwaps("javaguides");

}

public String reverseWithSwaps(String string) {

final char[] array = string.toCharArray();

final int length = array.length - 1;

final int half = (int) Math.floor(array.length / 2);

char c;

for (int i = length; i >= half; i--) {

c = array[length - i];

array[length - i] = array[i];

array[i] = c;

}

display(string, String.valueOf(array));

return String.valueOf(array);

}

private void display(String input, String output) {

System.out.println(" input string :: " + input);

System.out.println(" output string :: " + output);

}

}

输出：

input string :: javaguides

output string :: sediugavaj

5. 使用 XOR(^) 操作符反转

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseStringWithXOR {

public static void main(String[] args) {

ReverseStringWithXOR stringWithXOR = new ReverseStringWithXOR();

stringWithXOR.reverseWithXOR("javaguides");

}

public String reverseWithXOR(String string) {

final char[] array = string.toCharArray();

final int length = array.length;

final int half = (int) Math.floor(array.length / 2);

for (int i = 0; i < half; i++) {

array[i] ^= array[length - i - 1];

array[length - i - 1] ^= array[i];

array[i] ^= array[length - i - 1];

}

display(string, String.valueOf(array));

return String.valueOf(array);

}

private void display(String input, String output) {

System.out.println(" input string :: " + input);

System.out.println(" output string :: " + output);

}

}

输出：

input string :: javaguides

output string :: sediugavaj

6. 使用堆栈

package net.javaguides.corejava.string;

import java.util.Stack;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseStringUsingStack {

// Function to reverse a string in Java using a stack and character array

public static String reverse(String str) {

// base case: if string is null or empty

if (str == null || str.equals(""))

return str;

// create an empty stack of characters

Stack < Character > stack = new Stack < Character > ();

// push every character of the given string into the stack

char[] ch = str.toCharArray();

for (int i = 0; i < str.length(); i++)

stack.push(ch[i]);

// start from index 0

int k = 0;

// pop characters from the stack until it is empty

while (!stack.isEmpty()) {

// assign each popped character back to the character array

ch[k++] = stack.pop();

}

// convert the character array into string and return it

return String.copyValueOf(ch);

}

public static void main(String[] args) {

String str = "javaguides";

str = reverse(str); // string is immutable

System.out.println("Reverse of the given string is : " + str);

}

}

输出：

Reverse of the given string is : sediugavaj

7. 使用 Collections reverse() 方法

package net.javaguides.corejava.string;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseStringUsingCollectionsReverseMethod {

// Function to reverse a string in Java using Collections.reverse()

public static String reverse(String str) {

// base case: if string is null or empty

if (str == null || str.equals(""))

return str;

// create an empty list of characters

List < Character > list = new ArrayList < Character > ();

// push every character of the given string into it

for (char c: str.toCharArray())

list.add(c);

// reverse list using java.util.Collections reverse()

Collections.reverse(list);

// covert ArrayList into String using StringBuilder and return it

StringBuilder builder = new StringBuilder(list.size());

for (Character c: list)

builder.append(c);

return builder.toString();

}

public static void main(String[] args) {

String str = "Java Guides";

// String is immutable

str = reverse(str);

System.out.println("Reverse of the given string is : " + str);

}

}

输出：

Reverse of the given string is : sediuG avaJ

8. 使用 Byte 数组

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class ReverseStringUsingByteArray {

// Function to reverse a string in Java using byte array

public static String reverse(String str) {

// return if string is null or empty

if (str == null || str.equals(""))

return str;

// convert string into bytes

byte[] bytes = str.getBytes();

// start from the two end points l and h of the given string

// and increment l & decrement h at each iteration of the loop

// until two end-points intersect (l >= h)

for (int l = 0, h = str.length() - 1; l < h; l++, h--) {

// Swap values at l and h

byte temp = bytes[l];

bytes[l] = bytes[h];

bytes[h] = temp;

}

// convert byte array back into the string

return new String(bytes);

}

public static void main(String[] args) {

String str = "Java Guides";

// String is immutable

str = reverse(str);

System.out.println("Reverse of the given string is : " + str);

}

}

输出：

Reverse of the given string is : sediuG avaJ

9. 使用 substring() 方法

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class UsingSubStringFunction {

// Function to reverse a string in Java using recursion

private static String reverse(String str) {

// base case: if string is null or empty

if (str == null || str.equals(""))

return str;

// last character + recurse for remaining string

return str.charAt(str.length() - 1) + reverse(str.substring(0, str.length() - 1));

}

public static void main(String[] args) {

String str = "javaguides";

// string is immutable

str = reverse(str);

System.out.println("Reverse of the given string is : " + str);

}

}

输出：

Reverse of the given string is : sediugavaj

10. 使用递归

package net.javaguides.corejava.string;

/**

*

* @author Ramesh Fadatare

*

*/

public class UsingRecursion {

static int i = 0;

// Recursive function to reverse a string in Java using static variable

private static void reverse(char[] str, int k) {

// if we have reached the end of the string

if (k == str.length)

return;

// recurse for next character

reverse(str, k + 1);

if (i <= k) {

char temp = str[k];

str[k] = str[i];

str[i++] = temp;

}

}

public static String reverse(String str) {

// base case: if string is null or empty

if (str == null || str.equals(""))

return str;

// convert string into a character array

char[] A = str.toCharArray();

// reverse character array

reverse(A, 0);

// convert character array into the string

return String.copyValueOf(A);

}

public static void main(String[] args) {

String str = "Java Guides";

// string is immutable

str = reverse(str);

System.out.println("Reverse of the given string is : " + str);

}

}

输出：

Reverse of the given string is : sediuG avaJ