How do I do this in Java?

example.ts

interface Cat {
    id: number
    typ: "cat"
    data: {purrs: boolean}
}

interface Dog {
    id: number
    typ: "dog"
    data: {barks: boolean}
}

type Animal = Cat | Dog

const animals:Map<number, Animal> = new Map()

class Client {
    getAnimal(id:number):Animal|undefined { 
        return animals.get(id)
    }
    addAnimal(a:Animal) {
        animals.set(a.id, a)
    }
    getAnimals():Animal[] {
        return Array.from(animals.values())
    }
}


const client = new Client()
client.addAnimal({id: 1, typ: "cat", data:{purrs: true}})
client.addAnimal({id: 2, typ: "dog", data:{barks: false}})

console.log(client.getAnimals())

// prints 
// [
//     {id: 1, typ: "cat", data:{purrs: true}},
//     {id: 2, typ: "dog", data:{barks: false}}
// ]