public static int atoi(String str) {

//这里要小心，需要判断有效性

if (str == null || str.length() == 0) {

return 0;

}

int nlen = str.length();

double sum = 0;

int sign = 1;

int j = 0;

//剔除空格

while (str.charAt(j) == ' ') {

j++;

}

//判断正数和负数

if (str.charAt(j) == '+') {

sign = 1;

j++;

} else if (str.charAt(j) == '-') {

sign = -1;

j++;

}

for (int i = j; i < nlen; i++) {

char current = str.charAt(i);

if (current >= '0' && current <= '9') {

sum = sum * 10 + (int) (current - '0');

} else {

break;//碰到非数字，退出转换

}

}

sum = sum * sign;

//这里要小心，需要判断范围

if (sum > Integer.MAX_VALUE) {

sum = Integer.MAX_VALUE;

} else if (sum < Integer.MIN_VALUE) {

sum = Integer.MIN_VALUE;

}

return (int) sum;

}

/**

* 按照自然语言顺序排序

*

* @param list

*/

public static void naturalSort(Listlist) {

Collections.sort(list, (o1, o2) -> {

int i = 0, j = 0;

String temp1, temp2;

int num1, num2;

int length = Math.min(o1.length(), o2.length());

while (i < length && j < length) {

temp1 = "";

temp2 = "";

if (o1.charAt(i) > '9' || o1.charAt(i) < '0' || o2.charAt(j) > '9' || o2.charAt(j) < '0') {

if (o1.charAt(i) == o2.charAt(j)) {

i++;

j++;

continue;

} else if (o1.charAt(i) > o2.charAt(j)) {

return 1;

} else {

return -1;

}

}

while (i < o1.length() && o1.charAt(i) <= '9' && o1.charAt(i) >= '0') {

temp1 += o1.charAt(i);

i++;

}

while (j < o2.length() && o2.charAt(j) <= '9' && o2.charAt(j) >= '0') {

temp2 += o2.charAt(j);

j++;

}

num1 = atoi(temp1);

num2 = atoi(temp2);

if (num1 == num2) {

if (temp1.length() < temp2.length()) {

return 1;

} else if (temp1.length() > temp2.length()) {

return -1;

} else {

continue;

}

} else if (num1 > num2) {

return 1;

} else {

return -1;

}

}

return o1.length() > o2.length() ? 1 : -1;

});

}

public static void main(String[] args) {

Listlist = Arrays.asList("IM0.dcm", "IM1.dcm", "IM10.dcm", "IM11.dcm", "IM2.dcm", "IM20.dcm");

naturalSort(list);

System.out.println(list);

}

运行结果：