java字符串反转方法总结

描述：给我一个字符串，例如I love java,输出： java love I



方法一

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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 java

public 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));

}



}

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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 java

public 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));

}



}

方法二：（利用jdk提供的方法）

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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 java



List<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+" ");

}

}

}

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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 java



List<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+" ");

}

}

}


另外，如果描述改一下，输入一个字符串，例如“abcd”,输出"dcba"，



当然了方法很多，这里我提供一个jdk自带的方法，比较简单

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public static String reverse(String str){

return new StringBuilder(str).reverse().toString();

}

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public static String reverse(String str){

return new StringBuilder(str).reverse().toString();

}

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@Test

public 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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@Test

public void test09() {

String str = "hello";



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



char c = str.charAt(i);



System.out.print(c);

}