String inversion method summary, string inversion Summary

String inversion method summary, string inversion Summary

Description: Give me a string, for example, I love java. Output: java love I

Method 1

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1. Public class StringReverse {
3. Public void swap (char [] arr, int begin, int end ){
4. While (begin <end ){
5. Char temp = arr [begin];
6. Arr [begin] = arr [end];
7. Arr [end] = temp;
8. Begin ++;
9. End --;
10. }
11. }
12. // I love java
13. Public String swapWords (String str ){
14. Char [] arr = str. toCharArray ();
15. Swap (arr, 0, arr. length-1 );
16. Int begin = 0;
17. For (int I = 1; I <arr. length; I ++ ){
18. If (arr [I] = ''){
19. Swap (arr, begin, I-1 );
20. Begin = I + 1;
21. }
22. }
24. Return new String (arr );
25. }
27. Public static void main (String [] args ){
28. String str = "I love java ";
29. System. out. println (new StringReverse (). swapWords (str ));
30. }
32. }

public class StringReverse {public void swap(char[] arr, int begin, int end) {while(begin < end) {char temp = arr[begin];arr[begin] = arr[end];arr[end] = temp;begin++;end--;}}//I love javapublic String swapWords(String str) {char[] arr = str.toCharArray();swap(arr, 0, arr.length - 1);int begin = 0;for (int i = 1; i < arr.length; i++) {if (arr[i] == ' ') {swap(arr, begin, i - 1);begin = i + 1;}}return new String(arr);}public static void main(String[] args) {String str = "I love java";System.out.println(new StringReverse().swapWords(str));}}

Method 2: (use the method provided by jdk)

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1. Public class Main {
3. Public static void main (String [] args ){
4. Pipeline SC = new pipeline (System. in );
6. String str = SC. nextLine ();
8. String [] sArr = str. split (""); // I love java
10. List <String> list = new ArrayList <String> ();
12. List = Arrays. asList (sArr );
14. // For (int I = 0; I <sArr. length; I ++ ){
15. // List. add (sArr [I]);
16. //}
18. Collections. reverse (list );
20. For (String word: list ){
21. System. out. print (word + "");
22. }
23. }
24. }

public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);String str = sc.nextLine();String[] sArr = str.split(" ");//I love javaList<String> list = new ArrayList<String>();list = Arrays.asList(sArr);//for(int i=0;i<sArr.length;i++){//list.add(sArr[i]);//}Collections.reverse(list);for(String word:list){System.out.print(word+" ");}}}

If you change the description, enter a string, such as "abcd" and output "dcba ",

Of course there are many methods. Here I provide a method that comes with jdk, which is relatively simple.

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1. Public static String reverse (String str ){
2. Return new StringBuilder (str). reverse (). toString ();
3. }

public static String reverse(String str){return new StringBuilder(str).reverse().toString();}

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1. @ Test
2. Public void test09 (){
3. String str = "hello ";
5. For (int I = str. length ()-1; I> = 0; I --){
7. Char c = str. charAt (I );
9. System. out. print (c );
10. }
11. }

@Testpublic void test09() {String str = "hello";for (int i = str.length() - 1; i >= 0; i--) {char c = str.charAt(i);System.out.print(c);}}

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