Java实现去除字符串首尾空格

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Java中有自带的语句trim()可以去除字符串的首尾空格。

public class Demo3 {

	public static void main(String[] args) {
		String s = "       sa a        ";
		String newString = myTrim(s);
		System.out.println("去除字符串两边的空格后："+ newString);
		System.out.println("去除字符串两边的空格之前："+ s);

	}
	public static String myTrim(String s) {
		//确定首尾空格的个数
		int count_first = 0;
		int count_last = 0;
		char[] arr = s.toCharArray();
		int i = arr.length - 1;
		while(i>=0) {
			if (arr[i] == ' ') {
				count_last++;
				i--;
			}else {
				break;
			}
		}
		int j = 0;
		while(j<arr.length) {
			if (arr[j] == ' ') {
				count_first++;
				j++;
			}else {
				break;
			}
		}
		String newString;
		newString = s.substring(count_first, (arr.length - count_last));
		return newString;
	}
}