java中如何判断一个字符串是否为数字呢？

方式1,使用Character.isDigit方法对字符串进行判断

public static boolean isNumericCheck(String str) {
	for (int i = 0; i < str.length(); i++) {
		System.out.println(str.charAt(i));
		if (!Character.isDigit(str.charAt(i))) {
			return false;
		}
	}
	return true;
}

方式2：使用正则表达式

    public static boolean isNumericzidai(String str) {
        Pattern pattern = Pattern.compile("-?[0-9]+\\.?[0-9]*");
        Matcher isNum = pattern.matcher(str);
        if (!isNum.matches()) {
            return false;
        }
        return true;
    }

public static void main(String[] args) {
	double aa = -63434.7;
	String a = "-63434.7";
	String b = "-63434.7";
	String c = "网站";
	System.out.println(isNumericCheck(Double.toString(aa)));
	System.out.println(isNumericCheck(a));
	System.out.println(isNumericCheck(b));
	System.out.println(isNumericCheck(c));
}