Question

在这个例子中：

if (object instanceof SomeThing || object instanceof OtherThing) {
    System.out.println("this block was entered because of: " + **____** )
}

我可以检查真实情况是SomeThing还是OtherThing？

编辑：我正试图避免条件分离。

感谢。

Answer 1

将两种情况下的任何常见步骤重构为函数，然后：

if (object instanceof SomeThing) {
    // It's SomeThing
    System.out.println("Got here because it's SomeThing");
    commonStuff();
}
else if (object instanceof OtherThing) {
    // It's OtherThing
    System.out.println("Got here because it's OtherThing");
    commonStuff();
}

重新编辑：

编辑：我正试图避免条件分离。

然后你有这些选择：

if (object instanceof SomeThing || object instanceof OtherThing) {
    System.out.println("Got here because it's " +
        (object instanceof SomeThing) ? "SomeThing" : "OtherThing")
    );
}

或者

boolean isSomeThing:
if ((isSomeThing = object instanceof SomeThing) || object instanceof OtherThing) {
    System.out.println("Got here because it's " +
        isSomeThing ? "SomeThing" : "OtherThing")
    );
}

Answer 2

尝试

  if (object instanceof SomeThing ) {
        System.out.println("this block was entered because of: " + **SomeThing ____** )
    }   
  else if(object instanceof OtherThing){
     System.out.println("this block was entered because of: " + **OtherThing____** )
    }
  else{
     System.out.println("********nothing satisfied)
  }

Answer 3

if (object instanceof SomeThing || object instanceof OtherThing) {
     System.out.println(object instanceof SomeThing  );// if this print false then object is type of OtherThing

    System.out.println("this block was entered because of: " + **____** )
}

Answer 4

尝试使用三元运算符：

 if (object instanceof SomeThing || object instanceof OtherThing) {
        System.out.println("this block was entered because of: " 
           + (object instanceof SomeThing? "SomeThing" : "OtherThing") );
    }

Answer 5

System.out.println("This block was entered because object is instance of SomeThing or OtherThing.");

作为替代方案：

System.out.println("This block was entered because object is " + object.getClass().getName());

或者，非常不可读：

boolean other = false;
if (object instanceof SomeThing || (other = true) || ....) {
    System.out.println("because of " + other?"OtherThing":"SomeThing")
}

有没有办法找出哪个IF条件'触发'进入if（）{}块？

5 个答案: