写一个java程序，把一个字符串首字母转为大写，其余为小写

public class StringUpperLower {
public static void main(String[] args) {
String str = "This IS A STRING";
String newStr = "";
for(int i = 0; i < str.length(); i++){
char c = str.charAt(i);
if(i == 0){
newStr += Character.toUpperCase(c);
} else {
newStr += Character.toLowerCase(c);
}
}
System.out.println(newStr);
}
}