Question

我正在开设一个考勤应用。该应用的app:headerLayout="@layout/nav_header_main"由学生列表组成。我想将颜色改为红色和绿色，表示缺席和呈现。问题是如果我有很多学生而不是屏幕。当前视图向下或向上的项目会丢失颜色。我的方法是否正确？如何保存每个列表项的颜色。当然，如果除了使用ListActivity之外还有另一个最好的approch，我愿意接受建议。

这是包含列表

的ListActivity

ListView

我正在使用public class ListActivity extends Activity implements Serializable{ private String userName; private TextView nameTextView; private ListView nameList; private CustomAdapter adapter; private boolean colorRed; private Class myClass; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_list); myClass = new Class(); colorRed = false; // Open the students list from file if exists openFromFile(); nameList = (ListView) findViewById(R.id.nameListView); nameTextView = (TextView) findViewById(R.id.nameTextView); Bundle extras = getIntent().getExtras(); if (extras != null) { userName = extras.getString("NAME"); nameTextView.setText("Hi! " + userName); } adapter = new CustomAdapter(this, myClass.getStudentNames()); nameList.setAdapter(adapter); TextView tv = (TextView) findViewById(R.id.sNametv); nameList.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { if (colorRed == true) { view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorPresent)); colorRed = false; } else { view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorAbsent)); colorRed = true; } // ALso could use this // adapterView.getChildAt(position).setBackgroundColor(Color.RED); } }); }来检查颜色，因为我无法将视图颜色与boolean colorRed的颜色进行比较。

colors xml

ListView的CustomAdapter类

nameList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
            if (colorRed == true) {
                view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorPresent));
                colorRed = false;
            } else {
                     view.setBackgroundColor(ContextCompat.getColor(getBaseContext(),    R.color.colorAbsent));
                colorRed = true;
            }
        }
    });

我已经仔细检查过它是一个独特的问题！休息保证...

提前感谢

Answer 1

创建监听器接口：

public interface ListListener {
     void clickListItem(int position);
}

这是Model类：

public class Route {
    String studentName;
    boolean colorRed;

    public Route(String studentName, boolean colorRed) {
        this.studentName=studentName;
        this.colorRed=colorRed;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public boolean isColorRed() {
        return colorRed;
    }

    public void setColorRed(boolean colorRed) {
        this.colorRed = colorRed;
    }
}

创建适配器类：

public class AAdapter  extends BaseAdapter implements View.OnClickListener {

    Context context;
    private List<Route> routes;
    Holder holder;
    private static LayoutInflater inflater=null;
    ListListener listListener;

    public AAdapter(Context context, List<Route> names,ListListener listListener) {
       this.routes=names;
        this.context=context;
        this.listListener=listListener;
        inflater = ( LayoutInflater )context.
                getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public void onClick(View view) {
        listListener.clickListItem((Integer)view.getTag());
    }

    private class Holder
    {
        TextView tv;
    }

    @Override
    public Route getItem(int position) {
        return routes.get(position);
    }

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

    @Override
    public int getCount() {
        return routes.size();
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        if (convertView==null){
            holder=new Holder();

            convertView=inflater.inflate(R.layout.custom_layout,null);

            holder.tv=(TextView)convertView.findViewById(R.id.textView);
            holder.tv.setOnClickListener(this);
            convertView.setTag(holder);

        }else {
            holder=(Holder)convertView.getTag();
        }

        holder.tv.setText(routes.get(position).getStudentName());
        holder.tv.setTag(position);

        if (!routes.get(position).colorRed){
            holder.tv.setBackgroundColor(Color.GREEN);
        }else {
            holder.tv.setBackgroundColor(Color.RED);
        }
        return convertView;
    }
}

现在的MainActivity类：

public class MainActivity extends AppCompatActivity implements ListListener{

    AAdapter adapter;
    ListView lv;
    List<Route> myNames;
    ListListener listListener=MainActivity.this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv=(ListView)findViewById(R.id.listnames);


        myNames=new ArrayList<>();

        /* DEMO DATA U NEED TO FETCH YOUR DATA */
        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));


        adapter = new AAdapter(this, myNames,listListener);
        lv.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }

    @Override
    public void clickListItem(int position) {
        if(myNames.get(position).colorRed){
           myNames.get(position).colorRed=false;
        }else {
            myNames.get(position).colorRed=true;
        }
        adapter.notifyDataSetChanged();
    }
}

如何切换ListView项目颜色并保存？

1 个答案: