java泛型类

public abstract class Func{    public interface Func1<T, R>{         R apply(T t);    }    public interface Func2<T1,T2,R> {        R apply(T1 t1,T2 t2);    }    public interface Func3<T1,T2,T3,R> {        R apply(T1 t1,T2 t2,T3 t3);    }    public interface Func4<T1,T2,T3,T4,R> {        R apply(T1 t1,T2 t2,T3 t3);    }}