Imageview 在滚动列表视图上自动更改

Question

我是 android 新手，面临一个非常常见的 listview 问题，我在 Google 上搜索了很多，但没有找到任何对我的案例有用的东西。希望你们能告诉我正确的方向。每当我将图像从“加号”更改为单击“勾选”我的最后一个项目图像也会在滚动时自动更改。

我的 list_comapare_product XMl :-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white_color"
    android:orientation="vertical" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:background="@color/white_color"
        android:gravity="center_vertical" >

        <ImageView
            android:id="@+id/img_product"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:src="@drawable/crane" />

        <com.mss.skyjack.custom.views.SkyjackCustomTextview
            android:id="@+id/tv_product_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:gravity="center"
            android:text="test"
            android:textAppearance="?android:attr/textAppearanceMedium" />

        <ImageView
            android:id="@+id/img_plus"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:src="@drawable/plus" />
    </RelativeLayout>

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:background="@color/black_color" />

</LinearLayout>

这是我的适配器：-

import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;



public class ComapreProductSelectionAdapter extends BaseAdapter {
	Activity activity;
	List<SelectorTest> listSelector;
	private LayoutInflater mLayoutInflater;

	public ComapreProductSelectionAdapter(Activity activity,
			List<SelectorTest> listSelector) {
		this.activity = activity;
		this.listSelector = listSelector;
		mLayoutInflater = (LayoutInflater) activity
				.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
	}

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

	@Override
	public SelectorTest getItem(int position) {
		return listSelector.get(position);
	}

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

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		final ViewHolder viewHolder;
		final int i = position;
		final SelectorTest listItem = listSelector.get(position);

		if (convertView == null) {
			convertView = mLayoutInflater.inflate(
					R.layout.list_comapare_product, parent, false);
			viewHolder = new ViewHolder();
			viewHolder.tvProductName = (TextView) convertView
					.findViewById(R.id.tv_product_name);
			viewHolder.imgProduct = (ImageView) convertView
					.findViewById(R.id.img_product);
			viewHolder.imgadd = (ImageView) convertView
					.findViewById(R.id.img_plus);

			convertView.setTag(viewHolder);

		} else {
			viewHolder = (ViewHolder) convertView.getTag();
		}
		viewHolder.imgadd.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				if (viewHolder.imgadd.getDrawable().getConstantState() == activity
						.getResources().getDrawable(R.drawable.plus)
						.getConstantState()) {
					viewHolder.imgadd.setImageResource(R.drawable.tick);
				} else {
					viewHolder.imgadd.setImageResource(R.drawable.plus);
				}
				
			}
		});
		return convertView;
	}

	static class ViewHolder {
		TextView tvProductName;
		ImageView imgProduct, imgadd;
		View viewRightLine;
	}

}

谢谢。

Answer 1

您需要跟踪哪些项目已被“勾选”。我复制了您的适配器并进行了必要的更改。您只需复制粘贴代码即可。

import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;



public class ComapreProductSelectionAdapter extends BaseAdapter {
    Activity activity;
    List<SelectorTest> listSelector;
    private LayoutInflater mLayoutInflater;
    private ArrayList<Integer> tickedItems = new ArrayList<Integer>();

    public ComapreProductSelectionAdapter(Activity activity,
            List<SelectorTest> listSelector) {
        this.activity = activity;
        this.listSelector = listSelector;
        mLayoutInflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

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

    @Override
    public SelectorTest getItem(int position) {
        return listSelector.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final ViewHolder viewHolder;
        final int i = position;
        final SelectorTest listItem = listSelector.get(position);

        if (convertView == null) {
            convertView = mLayoutInflater.inflate(
                    R.layout.list_comapare_product, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.tvProductName = (TextView) convertView
                    .findViewById(R.id.tv_product_name);
            viewHolder.imgProduct = (ImageView) convertView
                    .findViewById(R.id.img_product);
            viewHolder.imgadd = (ImageView) convertView
                    .findViewById(R.id.img_plus);

            convertView.setTag(viewHolder);

        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.imgadd.setTag(position);

        viewHolder.imgadd.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                if(tickedItems.contains((Integer)v.getTag()) {
                   //Already ticked, set to plus
                    viewHolder.imgadd.setImageDrawable(activity.getResources().getDrawable(R.drawable.plus));
                    tickedItems.remove((Integer)v.getTag());
           } else {
                    tickedItems.add((Integer)v.getTag());
                    viewHolder.imgadd.setImageDrawable(activity.getResources().getDrawable(R.drawable.tick));
            }

            }
        });

        if(tickedItems.contains(position))
            viewHolder.imgadd.setImageDrawable(activity.getResources().getDrawable(R.drawable.tick));
        else
            viewHolder.imgadd.setImageDrawable(activity.getResources().getDrawable(R.drawable.plus));
        return convertView;
    }

    static class ViewHolder {
        TextView tvProductName;
        ImageView imgProduct, imgadd;
        View viewRightLine;
    }

}

另外，不要使用ImageView.setImageResource()，因为它效率低。

来自 Android 文档的关于 ImageView.setImageReource() 的引用

这会在 UI 线程上进行位图读取和解码，这可能会导致延迟中断。如果这是一个问题，请考虑使用 setImageDrawable(android.graphics.drawable.Drawable) 或 setImageBitmap(android.graphics.Bitmap) 和 BitmapFactory。