Dog dog2=animal無(wú)法執(zhí)行
在代碼中Dog dog=new Dog();是創(chuàng)建一個(gè)Dog類的dog對(duì)象，Animal animal=dog;是把Animal類的animal對(duì)象強(qiáng)制轉(zhuǎn)換成Dog類的animal對(duì)象，那么為什么Dog dog2=animal不能轉(zhuǎn)換成功？前面不是已經(jīng)把a(bǔ)nimal轉(zhuǎn)換成Dog類型了嗎？那為什么就不能轉(zhuǎn)換呢？為什么非要先把a(bǔ)nimal強(qiáng)制轉(zhuǎn)換成Dog類型呢，前面難道沒(méi)有轉(zhuǎn)換？
2019-10-19
前面是把Dog對(duì)象轉(zhuǎn)換成Animal對(duì)象，自動(dòng)類型轉(zhuǎn)換。Dog dog2 = animal是把Animal對(duì)象轉(zhuǎn)換成Dog對(duì)象，強(qiáng)制類型轉(zhuǎn)換。