String s = "12312312";判断是否是数字格式

package com;

public class Zixue1 {

public static void main(String[] args) {
String s = "12312312";
if (Zixue1.IsNumber(s)) {
System.out.println("是数字格式");
}else{
System.out.println("不是数字格式");
}
}

private static boolean IsNumber(String str) {
char[]c =str.toCharArray();
for (int i = 0; i < c.length; i++) {
if(Character.isDigit(c[i])){

}else{
return false;
}
}
return true;
}
}