编辑代码

class Main<T> {
    private T t;
    public void set(T t){
        this.t = t;
    }
    public T get(){
        return t;
    }
    public static void main(String[] arr){
        Main<String> main = new Main<String>();
        main.set("hello world");
        System.out.println(main.get());
    }

}