泛型

泛型类

public class test1 <T>{
private T a;
    public void setA(T a) {
        this.a = a;
    }
    public T getA() {
        return a;
    }
}

泛型方法

public class test1 {
    public <T> T show(T t){
        return t;
    }
}

泛型接口

public interface test2 <T>{
    T show(T t);
}
public class test1<T> implements test2<T>{
    public T show(T t) {
        return t;
    }
}

可变参数

public class test {
    public static void main(String[] args) {
        System.out.println(sum(10,20,30,40));
    }
    public static int sum(int...a){
        int s = 0;
        for (int i:a){
            s+=i;
        }
       return s;
    }
}