java在条件表达式中使用equals方法

Question

为什么这个条件语句不起作用？？ o1和o2是两个不同的物体

o1.equals(o2) ? System.out.println("Objects are equal"): System.out.println("Objects are not equal");

Answer 1

尝试用这种方式替换代码

System.out.println((o1.equals(o2) ? "Objects are equal" : "Objects are not equal"));

Answer 2

这叫做ternary operator。里面不能有语句

但你可以有表达方式

String output = o1.equals(o2) ? "Objects are equal":"Objects are not equal";

Answer 3

试试这个会有用的

System.out.println(o1.equals(o2) ? "Objects are equal": "Objects are not equal");

Answer 4

试试这个，conditional Operator

System.out.println((o1.equals(o2) ? "Objects are equal": "Objects are not equal"));

因为你的代码不是语句

Answer 5

根据Java语言规范，在“条件运算符”下-

It is a compile-time error for either the second or the third operand expression to be an invocation of a void method.

因为println是一个void方法，所以第二个和第三个操作数表达式满足这个条件。至于为什么它是这样工作的——这就是Java的定义方式