Android单选列表的实现

项目需要实现的效果：

项目需求：

简单的说一下项目需求，人员管理时添加和编辑岗位，需要一个岗位的单选列表。我没找到现成的控件，所以我自己手写了一个。

说一下实现的思路：其实就是一个ListView，列表元素内含两个元素，第一个是textView,第二个就是ImageView,默认不显示√,点击后显示√。

思路很清晰，但是在实现的时候我遇到了一些问题，查过一些博客，关键就是关于列表元素下标的问题。

项目实现：

先上代码：

这段代码是项目列表：

因为是与后台交互，需要向服务器请求数据，initData实现这个功能。

其次我选择RecyclerView，ListView也行，这不纠结。需要将选择到的信息传到上一级活动，使用Intent实现传值，其他方法也有，比如bundle传值，这个不纠结。index初始化为-1。代码有点乱，这个以后我得改。

public class JobListActivity extends BaseActivity implements View.OnClickListener {

    private TextView nav_title;
    private RecyclerView rv_select_job;
    private SelectListAdapter adapter;
    private List listdata = new ArrayList<>();
    private List jobBeanList = new ArrayList<>();
    private ArrayList mPostIds = new ArrayList<>();
    private ArrayList mPostNames = new ArrayList<>();
    private String mIndex = "-1";
    private String info;
    private ImageView back;
    private TextView add;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_job_list);
        mIndex = getIntent().getStringExtra("mIndex");
        initData();
        initView();
    }

    //初始化数据
    public void initData() {
         //这个使用网络请求框架请求数据，得到相关数据。
        AdminApi.getInstance().getJob().subscribe(new OriginalSubscriber>(compositeDisposable) {

            @Override
            public void onError(ResponseThrowable e) {
                ToastUtil.show(JobListActivity.this, e.getMsg());
            }

            @Override
            public void onNext(List jobBeans, String msg) {
                jobBeanList = jobBeans;
                if (jobBeanList != null && jobBeanList.size() > 0) {
                    for (JobBean job : jobBeanList) {
                        listdata.add(new PostBean(job.getId(), job.getName(), false));
                    }
                    mPostIds.add("-1");
                }
                adapter = new SelectListAdapter(JobListActivity.this, listdata, mPostIds);
                adapter.setmIndex(mIndex);
                rv_select_job.setAdapter(adapter);
            }
        });

    }

    public void initView()
    {

        nav_title=findViewById(R.id.nav_txt_title);
        nav_title.setText("选择岗位");
        findViewById(R.id.nav_img_back).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                JobListActivity.this.finish();
            }
        });
       
        add = findViewById(R.id.nav_btn_add);
        add.setText("确定");
        add.setVisibility(View.VISIBLE);
        add.setOnClickListener(this);
        rv_select_job=findViewById(R.id.rv_job);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        rv_select_job.setLayoutManager(linearLayoutManager);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.nav_btn_add:
                if (adapter.getPostidLists() != null && adapter.getPostidLists().size() > 0) {                
                    //传值，从数据库获得的index和岗位名称信息，传到上一级Activity
                    Intent intent = new Intent();
                    intent.putExtra("mIndex", adapter.getPostidLists().get(0));
                    intent.putExtra("info", adapter.getNameLists().get(0));
                    setResult(Activity.RESULT_OK, intent);

                    //及时finish
                    JobListActivity.this.finish();

                } else {
                    ToastUtil.show(this, "请选择岗位");
                }

        }

    }
}

其次应该就是重点的Adapter类了，遇到的问题就是index的判断了，因为是选择和编辑都使用这个活动，所以Adapter还需要实现列表的默认值问题，如果是添加，则默认都不显示√，如果是编辑，则需要显示默认的岗位。所以index就很关键。

这里之所以index会如此麻烦，是因为我们的后端传回的index是从1开始的，所以需要处理一下才能转回。

public class SelectListAdapter extends RecyclerView.Adapter {
    public Context mContext;
    private final int COUNT=6;
    private List listDataBeans;
    private ArrayList postidLists = new ArrayList<>();
    int index = -1;
    private String mIndex = "-1";
    private ArrayList projectIdList = new ArrayList<>();
    private ArrayList nameLists = new ArrayList<>();
    private ArrayList codeLists = new ArrayList<>();

    public SelectListAdapter(Context mContext, List listDataBeans, ArrayList listids) {
        this.mContext = mContext;
        this.listDataBeans = listDataBeans;
        if (listids != null) {
            this.postidLists.addAll(postidLists);
        }
    }

    public void setmIndex(String Index) {

        if (!Index.equals("-1")) {
            mIndex = Index;
            index = Integer.parseInt(mIndex) - 1;
        }
    }

    public List getListDataBeans() {
        return listDataBeans;
    }
    public ArrayList getProjectIdList() {
        return projectIdList;
    }
    public ArrayList getPostidLists() {
        return postidLists;
    }
    public ArrayList getNameLists() {
        return nameLists;
    }
    public ArrayList getCodeLists() {
        return codeLists;
    }


    @Override
    public void onBindViewHolder(@NonNull SelectListAdapter.ViewHolder viewHolder, int i) {
        PostBean bean = listDataBeans.get(i);
        viewHolder.iv_check.setImageResource(R.drawable.check);
        //初始化各个集合，判断标准为index，及第一次是否选择元素，否则就不显示图片
        if (index > -1) {
            listDataBeans.get(index).setSelected(true);
            postidLists.add(index + 1 + "");
            nameLists.add(listDataBeans.get(index).getName());
            projectIdList.add(listDataBeans.get(index).getId());
            codeLists.add(listDataBeans.get(index).getCode());
        }

        //下标相同则显示图片
        if (postidLists.contains(bean.getId()))
        {
            viewHolder.iv_check.setVisibility(View.VISIBLE);
            if (!nameLists.contains(bean.getName())) {
                nameLists.add(bean.getName());
            }
        }
        else{
            viewHolder.iv_check.setVisibility(View.INVISIBLE);
        }

//根据元素的图片标志位来显示图片
        viewHolder.iv_check.setVisibility(listDataBeans.get(i).isSelected() ? View.VISIBLE : View.INVISIBLE);

//显示具体数值
        if (listDataBeans.get(i).getCode() != null)
            viewHolder.tv_jop.setText(listDataBeans.get(i).getCode() + "\t\t\t\t" + listDataBeans.get(i).getName());
            else
                viewHolder.tv_jop.setText(listDataBeans.get(i).getName());

           //刷新
        viewHolder.itemView.setOnClickListener(v->{
            //将所有集合的数据清空
            postidLists.clear();
            nameLists.clear();
            projectIdList.clear();
            codeLists.clear();

            //添加数据
            postidLists.add(i + 1 + "");
            nameLists.add(listDataBeans.get(i).getName());
            projectIdList.add(listDataBeans.get(i).getId());
            if (codeLists != null) {
                codeLists.add(listDataBeans.get(i).getCode());
            }
           
           //其余元素的imageView标志位为false
            for (PostBean post : listDataBeans) {
                post.setSelected(false);
            }

           //imageView标志位为True
            listDataBeans.get(i).setSelected(true);

           //刷新
            notifyDataSetChanged();
            index = -1;
        });

    }

    @NonNull
    @Override
    public SelectListAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View v = LayoutInflater.from(mContext).inflate(R.layout.item_job_list, viewGroup, false);
        ViewHolder holder = new ViewHolder(v);
        return holder;
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        private TextView tv_jop;
        private ImageView iv_check;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            tv_jop = itemView.findViewById(R.id.tv_group);
            iv_check = itemView.findViewById(R.id.iv_check);
        }
    }

    @Override
    public int getItemCount() {
        if (listDataBeans == null) {
            return 0;
        }
        return listDataBeans.size();
    }


}

数据项

public class PostBean {
    String id;
    String name;
    String code;

    boolean isSelected;

    public PostBean() {

    }

    public PostBean(String id, String name, boolean isSelected) {
        this.id = id;
        this.name = name;
        this.isSelected = isSelected;
    }

    public PostBean(String id, String name, String code, boolean isSelected) {
        this.id = id;
        this.name = name;
        this.code = code;
        this.isSelected = isSelected;
    }
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public boolean isSelected() {
        return isSelected;
    }

    public void setSelected(boolean selected) {
        isSelected = selected;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

}

我这写的也有点乱，也没有专门整理一下，大体理个思路。

参考了很多。