自定义方法使用方法:

 

 

public class GeneriMethodTest {

    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        list.add("aa");
        list.add("bb");
        list.add("cc");
        Object[] array = list.toArray();
        System.out.println(Arrays.toString(array));

        String[] strings = list.toArray(new String[list.size()]);
        System.out.println(Arrays.toString(strings));

        show(1);
        show("hh");
        show(true);
    }

    private static <T> void show(T t) {
        System.out.println(t);
    }

}