java重载-方法重载中的准确性原则

大家先猜猜看下边这段程序执行结果

public class StringUtil {
	
	/**
	 * 判断输入的字符串是否是null或""
	 * 
	 * @param str
	 * @return
	 */
	public static boolean isEmpty(String str) {
		System.out.println("222222222::::::::::"+str);
		if (str == null || "".equals(str.trim()))
			return true;
		return false;
	}

	/**
	 * 判断输入的对象是否是null或""
	 * 
	 * @param obj
	 * @return
	 */
	public static boolean isEmpty(Object obj) {
		System.out.println("11111111::::::::::"+obj);
		return obj == null || "".equals(obj.toString());
	}
	

	
	public static void main(String[] args) {
		String s = " ss ";
		isEmpty(s);
		
		Integer i = 10;
		isEmpty(i);
		
		isEmpty(null);
		
		isEmpty((Object)null);
		isEmpty((Double)null);
	}
}public class StringUtil