public class HelloWorld {
public static void main(String[] args) {
int one = 20 ;
if(one%2=0);{
System.out.println("one是偶数");
}
else{
System.out.println("one不是偶数");
左括号匹配离他最近的右括号 if(one%2=0);改成 if(one%2==0)