java 判断字符串全为汉字 提取字符串中的汉字

1.判断字符串是否全为汉字

String str1 = "java判断是否为汉字"
        String str2 = "全为汉字"
        String reg = "[\u4e00-\u9fa5]+"
        boolean result1 = str1.matches(reg)//false
        boolean result2 = str2.matches(reg)//true

String str = "java怎么把asdasd字符串中的asdasd的汉字取出来";
        String reg = "[^u4e00-u9fa5]";
        str = str.replaceAll(reg, " ");
        System.out.println(str);

boolean result = (str.length() == str.getBytes().length)//true:无汉字  false:有汉字

int count = 0;
        String reg = "[\u4e00-\u9fa5]";
        String str = "java获取汉字Chinese的个数";
        Pattern p = Pattern.compile(reg);
        Matcher m = p.matcher(str);
        while (m.find()) {
            for (int i = 0; i <= m.groupCount(); i++) {
                count = count + 1;
            }
        }
        System.out.println("共有汉字 " + count + "个 ");