String a = null; String z=a==null?"1":a;
根据楼上的修改下,少个空字符串假设a为传入值String a = null; String z=(a!=null)&&(a.trim()!="")?"1":"2";1不是 2是
s1= (s1== null || s1.length() <= 0)?"1":"2";为空 = 1