public  class Test{
	public static void main(String []args){
		String aa = "123";
		boolean flag = isNum(aa );
	}
	public static  boolean isNum(String aa){
		Pattern pattern = Pattern.compile("[0-9]*");
		Matcher matcher  = pattern.matcher(aa);
		if(!matcher.matchers()){
			return false;
		} else{
			return true;
		}
	}
}


判斷是否字串是否含有數字或字母
public class Test {
	public static void main(String[] args) {
		String aString = "1";
		Pattern pattern1 = Pattern.compile("[a-zA-Z]*");
		Pattern pattern2 = Pattern.compile("[0-9]*");
		Pattern pattern3 = Pattern.compile("[a-zA-Z0-9]*");
		Matcher matcher1 = pattern1.matcher(aString);
		Matcher matcher2 = pattern2.matcher(aString);
		Matcher matcher3 = pattern3.matcher(aString);
		if (matcher1.matches()) {
			System.out.println("只含有字母");
		} else if (matcher2.matches()) {
			System.out.println("只含有數字");
		} else if (matcher3.matches()) {
			System.out.println("含有數字或字母");
		}
	}
}

public static void main(String[] args) {
		String aString = "19 A aw我~";
		char[]chars = aString.toCharArray();
		for(int i=0;i<chars.length;i++){
			if(chars[i]>=47 &&chars[i]<=57){
				System.out.println("含有數字"+String.valueOf(chars[i]));
			}else
			if((chars[i]>=65 &&chars[i]<=97)||(chars[i]>=97 &&chars[i]<=122)){
				System.out.println("含有字母"+String.valueOf(chars[i]));
			}else
			if((chars[i]==32)){
				System.out.println("含有空格"+String.valueOf(chars[i]));
			}else {
				System.out.println("含有漢字"+String.valueOf(chars[i]));
			}
		}