java运算优先级

public class testIsNull {
/**
* 判断是否为null
*/
public static void main(String[] args) {
Object o = new Object ();
o = null;
System.out.println("aaa="+o);
System.out.println("bbb="+o==null);
System.out.println("ccc="+ (o == null));
}
}

aaa=null
false
ccc=true