如何随机选择列表视图上的项目[关闭]

Question

早上好 我一直在尝试一切但没有成功 我的问题是我想从列表视图中选择随机项目并将其打印在标签中 我使用 java 安卓 谢谢

Answer 1

你可以关注library。

1. 使用this 选择数组：

    ListView listView = (ListView)findViewById(android.R.id.list);
    private List<String> items = Arrays.asList("One World Trade Center", "Empire State Building", "Bank of America Building", "Chrysler Building",....);

    adapter = new MyArrayAdapter(savedInstanceState, this, items);
    adapter.setAdapterView(listView);
    adapter.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
            Toast.makeText(this, "Item click: " + adapter.getItem(position), Toast.LENGTH_SHORT).show();
        }
    });

1. 对于随机选择，只需从数组中随机选择位置然后进行检查。

    public List<Integer> getRandomInterList(int n, int all) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < all; i++) {
            list.add(i);
        }
        Map map = new HashMap();
        List listNew = new ArrayList();
        if (list.size() <= n) {
            System.out.println(listNew + "===========" + listNew.toString());
            return listNew;
        } else {
            while (map.size() < n) {
                int random = (int) (Math.random() * list.size());
                if (!map.containsKey(random)) {
                    map.put(random, "");
                    System.out.println(random + "===========" + list.get(random));
                    listNew.add(list.get(random));
                }
            }
            System.out.println(listNew + "===========" + listNew.toString());
            return listNew;
        }
    }

    List<Integer> list =  getRandomInterList(2,items.size());
    for (int i = 0; i < list.size(); i++) {
        adapter. setItemChecked(i);
    }