Solution for :Cannot make a static reference to the non-static method

最近在学习java，作为java的菜鸟和以前C语言思维带来的影响，在弄java时经常犯一些比较低级的错误，弄清楚这些低级的错误对于理解java有很好的帮助。所以记录一下。

Cannot make a static reference to the non-static method 这个错误估计是最常见的，当时还觉得奇怪为什么是这样的情况呢。

比如我写了下面 一段java的测试小程序来检验一个字符串是否是数字：

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TestStrIsNum {
public  boolean isNumeric(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[] argv)
{
String a =new String("-1000");

//if (isNumeric(a)) error:Cannot make a static reference to the non-static method
TestStrIsNum test = new TestStrIsNum();
if (test.isNumeric(a))
System.out.println("a = -1000 is a number");
}
}

Analysis and soultion:

You can't make a static reference to the non-static method, so you can change the un-static method to a static method or you need to create an object using new operator and call the method by object.method().

stackoverflow上explaination：
http://stackoverflow.com/questions/23860661/cannot-make-a-static-reference-to-the-non-static-method