版权声明：本文为博主原创文章，转载希望能注明出处，感谢。 https://blog.csdn.net/u010126792/article/details/82495069
public class Demo13 {
public static void main(String[] args) throws Exception {
String s1 = "-092376";
String s2 = "-a92376";
String s3 = "92376";
String s4 = "923a76";
System.out.println("s1转换前的str：" + s1);
System.out.println("s1转换后的int：" + stringtoint(s1));
System.out.println("s2转换前的str：" + s2);
System.out.println("s2转换后的int：" + stringtoint(s2));
System.out.println("s3转换前的str：" + s3);
System.out.println("s3转换后的int：" + stringtoint(s3));
System.out.println("s4转换前的str：" + s4);
System.out.println("s4转换后的int：" + stringtoint(s4));
}
/**
* 不用内置转换函数把String转换成int -1 代表转换失败
*
* @param strnum
* @return
*/
public static int stringtoint(String strnum) {
int number = 0;
char navigaTag = '-';
boolean isNavigate = false;
if (strnum == null || strnum.length() == 0) {
return -1;
}
// char[] straar = strnum.toCharArray();
for (int i = 0; i < strnum.length(); i++) {
if (i == 0) {
if (strnum.charAt(0) == navigaTag) {
isNavigate = true;
continue;
}
}
char sinChar = strnum.charAt(i);
if (sinChar > '9' || sinChar < '0') {
return -1;
}
number = number * 10;// 每次*10添加到个位
// 会转换成ASCII码对应的十进制值进行运算，'9'-'0'= 9
number += strnum.charAt(i) - '0';
}
return isNavigate ? number * -1 : number;
}
}