常见java基础方法

--数组转list
List<String> strList = Arrays.asList("AA", "BB", "CC");

-- 数组转化为字符串中间拼接','

String newStr = String.join(",", strList);

    /**
     * 比较两个double类型数是否相等
     * @param num1
     * @param num2
     * @return
     */
    public boolean isxdDouble(double num1, double num2) {
        double preErrorKey=1e-6; //1*10的-6次方即0.000001
        double key1=0.0000001d;
        double key2=0d;
        return Math.abs(key1-key2)<preErrorKey;
    }

--获取绝对值

Math.abs() 获取绝对值