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

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));
    }

}

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）

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+" ");
        }
    }
}

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

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

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

@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);
        }
    }

@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);
		}
	}