在ListView中加载多个图像

Question

我正在学习NewBoston教程(https://www.youtube.com/watch?v=nOdSARCVYic&list=PL6gx4Cwl9DGBsvRxJJOzG4r4k_zLKrnxl&索引=48）

他展示了如何将图像放入列表，但他从未展示如何为每段文本分配不同的图像。

这是我的MainActivity。

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    String[] Jobsites = {"River Park Place", "Mayfair", "Jameson House"};
    ListAdapter jobsiteAdapter = new CustomAdapter(this, Jobsites);
    ListView jobsiteListView = (ListView) findViewById(R.id.jobsiteListView);
    jobsiteListView.setAdapter(jobsiteAdapter);
    jobsiteListView.setOnItemClickListener(
            new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    String jobsite = String.valueOf(parent.getItemAtPosition(position));
                    //Toast.makeText(MainActivity.this, jobsite, Toast.LENGTH_LONG).show();
                    if (jobsite == "River Park Place"){
                        //Perform segue to the proper view where employess can sign in
                        //******************************************
                        System.out.println("*****************");
                        System.out.println("Attempting to segue");
                        System.out.println("*****************");

                        //******************************************
                    }else{
                        System.out.println("*****************");
                        System.out.println("These jobsites aren't avaliable yet!");
                        System.out.println("*****************");
                        Toast.makeText(MainActivity.this, "**These Sites aren't avaliable yet!**", Toast.LENGTH_LONG).show();
                    }
                }
            }
        );
    }
}

在视频中，我们制作了一个处理图像的自定义视图。这是代码。

class CustomAdapter extends ArrayAdapter<String> {

public CustomAdapter(Context context, String[] jobsites) {
    super(context,R.layout.custom_row ,jobsites);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater jobsiteInflater = LayoutInflater.from(getContext());
    View customView = jobsiteInflater.inflate(R.layout.custom_row, parent, false);
    String singleJobsiteItem = getItem(position);
    ImageView josbiteImage = (ImageView) customView.findViewById(R.id.josbiteImage);
    josbiteImage.setImageResource(R.drawable.riverparkplace);

    return customView;
    }
}

我还有另外两张图片要添加到列表中最下面的两项文本中。现在，它只是一遍又一遍地为列表中的所有三行加载相同的图片。

Answer 1

让我一步一步地指导您。在我们继续之前，您需要了解ListView的ArrayAdapter会用您指定的数据填充每一行。换句话说，您希望像处理Jobsites字符串数组一样将图像传递给适配器。

1. 定义一个包含字符串（Jobsites）和要分配给它的图像的simple wrapper object。

   public class SimpleObject {
       private String jobSite;
       private int imageID; // your R.drawable.image
       public SimpleObject(String jobSite, int imageID) {
           this.jobSite = jobSite;
           this.imageID = imageID;
       }
       public String getJobSite() {
           return jobSite;
       }
       public int getImageID() {
           return imageID;
       }
   }
   

2. 初始化适配器要使用的SimpleObject阵列。在主活动的onCreate()中，执行以下操作：

   ArrayList<SimpleObject> objectList = new ArrayList<>();
   objectList.add(new SimpleObject("River Park Place", R.drawable.image1);
   objectList.add(new SimpleObject("Mayfair", R.drawable.image2);
   // the list goes on....
   

3. 现在，将CustomAdapter更改为保持SimpleObject而不是String:

   class CustomAdapter extends ArrayAdapter<SimpleObject> {
   
       public CustomAdapter(Context context, ArrayList<SimpleObject> objectList) {
           super(context,R.layout.custom_row ,objectList);
       }
       @Override
       public View getView(int position, View convertView, ViewGroup parent) {
           LayoutInflater jobsiteInflater = LayoutInflater.from(getContext());
           View customView = jobsiteInflater.inflate(R.layout.custom_row, parent, false);
           // Get the SimpleObject
           SimpleObject item = (SimpleObject) getItem(position);
           String singleJobsiteItem = item.getJobSite(); // get the String
           ImageView josbiteImage = (ImageView) customView.findViewById(R.id.josbiteImage);
           josbiteImage.setImageResource(item.getImageID()); // get the image ID and assign it to jobsiteImage :)
   
           return customView;
       }
   }
   

4. 现在，请确保在主活动中使用新的SimpleObject列表初始化适配器：

   ListAdapter jobsiteAdapter = new CustomAdapter(this, objectList);
   

Answer 2

您需要实现baseadapter，因为图像