如何根据位置更改listView项目的颜色

Posted 2023-04-19

【中文标题】如何根据位置更改listView项目的颜色

【英文标题】：How to change color of listView item depending on position

【发布时间】：2020-12-03 15:11:29

【问题描述】：

如何根据位置更改 listView 项目的颜色？我不能解决这个问题大约 4 天。也许有人可以帮助我。

我有 customView 类：

public class CustomView extends View  

    private String[] hoursList = getResources().getStringArray(R.array.hours); ;
    private String[] minutesList = getResources().getStringArray(R.array.minutes);;
    private String[] dayOfTimeList = getResources().getStringArray(R.array.timeOfDay);
    private ListView listView;
    private HourAdapter hourAdapter;
    private MinuteAdapter minuteAdapter;
    private DayOfTimeAdapter dayOfTimeAdapter;
    public static int middlePosition;



     public CustomView(Context context) 
            super(context);
        
    
        public CustomView(Context context, ViewGroup viewGroup) 
            super(context);
            inflate(context, R.layout.custom_test, viewGroup);
    
   
            listView = viewGroup.findViewById(R.id.hours_list);
            hourAdapter = new HourAdapter(context, hoursList);
            listView.setAdapter(hourAdapter);
    
            listView.setOnScrollListener(new AbsListView.OnScrollListener() 
    
                                             @Override
                                             public void onScrollStateChanged(AbsListView view, int scrollState) 
                                             
    
                                             @Override
                                             public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) 
                                              middlePosition = firstVisibleItem+1;
    
                                             
                                         
            );

    
        
    

和适配器类：

 public class HourAdapter extends BaseAdapter 
        private LayoutInflater lInflater;
        private String[] hoursValueList;
    
        public HourAdapter(Context context, String[] hoursValueList
            lInflater = LayoutInflater.from(context);
            this.hoursValueList = hoursValueList;
        

        @Override
        public View getView(int position, View convertView,ViewGroup parent) 
            View view = convertView;
          if (view == null) 
                view = lInflater.inflate(R.layout.row, parent, false);
            
    
            TextView textHours = view.findViewById(R.id.textRow);
            textHours.setText(hoursValueList[position]);
            
            if (position == CustomView.middlePosition) 
              view.setBackgroundResource(R.drawable.selected_color);
            
    
            return view;
        
    

What I need: when any element is in the middle position it has another color. 

但是使用我现在拥有的代码，它不起作用。每个第二个元素都有颜色， 但我需要将任何位于中间位置的元素着色

【问题讨论】：

您遇到了什么样的问题？

我得到了图片中的结果。元素未绘制。

图片我看不到

对不起，我加了。

【参考方案1】：

试试下面的代码：

CustomAdapter.java：

public class CustomAdapter extends BaseAdapter 
private LayoutInflater lInflater;
private String[] valueList;

public CustomAdapter(Context context, String[] valueList) 
    lInflater = LayoutInflater.from(context);
    this.valueList = valueList;


@Override
public int getCount() 
    return valueList.length;


@Override
public Object getItem(int position) 
    return valueList[position];


@Override
public long getItemId(int position) 
    return position;


@Override
public View getView(int position, View convertView, ViewGroup parent) 
    View view = convertView;
    if (view == null) 
        view = lInflater.inflate(R.layout.row, parent, false);
    
    TextView text = view.findViewById(R.id.textRow);
    text.setText(valueList[position]);
    return view;

CustomView.java：

public class CustomView extends View 

private String[] hoursList;
private String[] minutesList;
private String[] dayOfTimeList;
private ListView hoursListView;
private ListView minutesListView;
private ListView dayOfTimeListView;
private CustomAdapter hoursAdapter;
private CustomAdapter minutesAdapter;
private CustomAdapter dayOfTimeAdapter;

AbsListView.OnScrollListener scrollListener = new AbsListView.OnScrollListener() 
    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) 
        if (scrollState == SCROLL_STATE_IDLE) 
            View firstView = view.getChildAt(0);
            int offset = view.getTop() - firstView.getTop();
            if (offset > (firstView.getHeight() / 2)) 
                view.smoothScrollToPosition(view.getLastVisiblePosition());
             else 
                view.smoothScrollToPosition(view.getFirstVisiblePosition());
            
        
    

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) 
        for (int i = 0; i < view.getChildCount(); i++) 
            View childView = view.getChildAt(i);
            if (i == 1) childView.setBackgroundColor(Color.BLUE); else childView.setBackgroundColor(Color.WHITE);
        
    
;

public CustomView(Context context) 
    super(context);


public CustomView(Context context, ViewGroup viewGroup) 
    super(context);
    inflate(context, R.layout.custom_test, viewGroup);

    hoursList = new String[26];
    hoursList[0] = " ";
    hoursList[25] = " ";
    for (int i = 1; i < hoursList.length - 1; i++) hoursList[i] = String.valueOf(i);
    minutesList = new String[62];
    minutesList[0] = " ";
    minutesList[61] = " ";
    for (int i = 1; i < minutesList.length - 1; i++) minutesList[i] = String.valueOf(i);
    dayOfTimeList = new String[4];
    dayOfTimeList[0] = " ";
    dayOfTimeList[1] = "AM";
    dayOfTimeList[2] = "PM";
    dayOfTimeList[3] = " ";

    hoursListView = viewGroup.findViewById(R.id.hours_list);
    hoursAdapter = new CustomAdapter(context, hoursList);
    hoursListView.setAdapter(hoursAdapter);
    minutesListView = viewGroup.findViewById(R.id.minutes_list);
    minutesAdapter = new CustomAdapter(context, minutesList);
    minutesListView.setAdapter(minutesAdapter);
    dayOfTimeListView = viewGroup.findViewById(R.id.dayOfTime_list);
    dayOfTimeAdapter = new CustomAdapter(context, dayOfTimeList);
    dayOfTimeListView.setAdapter(dayOfTimeAdapter);

    hoursListView.setOnScrollListener(scrollListener);
    minutesListView.setOnScrollListener(scrollListener);
    dayOfTimeListView.setOnScrollListener(scrollListener);

要为第二个元素着色，需要重置其他元素的颜色。请注意，如果最初显示 3 行，则在滚动期间/之后可能会有 4 行（2 部分显示和 2 完全显示）。第二个元素可能偏离中间位置。