- // 如何判断一个字符是数字
- public class Test
- {
- /* 测试函数 */
- public static void main(String[] args)
- {
- char[] ch =
- {
- 'a', '1', 'b', '2', 'c', '3', 'd', '4',
- };
- System.out.println(ch[0] + ": " + isDigitA(ch[0]));
- System.out.println(ch[1] + ": " + isDigitA(ch[1]));
- System.out.println(ch[2] + ": " + isDigitB(ch[2]));
- System.out.println(ch[3] + ": " + isDigitB(ch[3]));
- System.out.println(ch[4] + ": " + isDigitC(ch[4]));
- System.out.println(ch[5] + ": " + isDigitC(ch[5]));
- System.out.println(ch[6] + ": " + isDigitD(ch[6]));
- System.out.println(ch[7] + ": " + isDigitD(ch[7]));
- }
- /* 1.用JAVA自带的函数 */
- private static boolean isDigitA(char ch)
- {
- return Character.isDigit(ch);
- }
- /* 2.用正则表达式 */
- private static boolean isDigitB(char ch)
- {
- Pattern pattern = Pattern.compile("[0-9]");
- return pattern.matcher(String.valueOf(ch)).matches();
- }
- /* 3.用ascii码 */
- private static boolean isDigitC(char ch)
- {
- if (ch < 48 || ch > 57)
- return false;
- else
- return true;
- }
- /* 4.强制类型转化是否抛出异常来判断 */
- private static boolean isDigitD(char ch)
- {
- try
- {
- int i = Integer.parseInt(String.valueOf(ch));
- return true;
- }
- catch (NumberFormatException e)
- {
- e.printStackTrace();
- return false;
- }
- }
- }
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