isDigit(): true if the argument is a digit (0 to 9), and false otherwise.
public class MainClass {
public static void main(String[] args) {
char symbol = 'A';
if (Character.isDigit(symbol)) {
System.out.println("true");
}else{
System.out.println("false");
}
}
}
Validate if a String contains only numbers
public class Main {
public static boolean containsOnlyNumbers(String str) {
for (int i = 0; i < str.length(); i++) {
if (!Character.isDigit(str.charAt(i)))
return false;
}/*from ww w . j av a 2 s.com*/
return true;
}
public static void main(String[] args) {
System.out.println(containsOnlyNumbers("123456"));
System.out.println(containsOnlyNumbers("123abc456"));
}
}
运行结果如下:
isLetterOrDigit(): true if the argument is a letter or a digit, and false otherwise.
public class MainClass {
public static void main(String[] args) {
char symbol = "A";
/*from w w w.j a v a 2 s. com*/
if (Character.isLetterOrDigit(symbol)) {
System.out.println("true");
}else{
System.out.println("false");
}
}
}
【char】
