Java中String判断为空的4大方法比较

public class demo1 {
   public static void main(String[] args) {
       String a="";
       String a2=new String();

       System.out.println(a=="");
       System.out.println(a2=="");
       System.out.println("------------------------------");
       System.out.println(a==null);
       System.out.println(a2==null);
       System.out.println("------------------------------");
       System.out.println(a.length()<=0);
       System.out.println(a2.length()<=0);
       System.out.println("------------------------------");
       System.out.println(a.isEmpty());
       System.out.println(a2.isEmpty());
       System.out.println("------------------------------");
       
   }
}