Question

我想创建一个列表视图，该列表视图多次显示相同的可点击图标。我尝试了许多方法，包括使用带布局填充器的自定义适配器，但失败了……此时，我的ListView显示数字而不是图标。你能帮我吗？这是我的代码

public class UserSelectionActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {

static ArrayList<Integer> arrayOfIcons = new ArrayList<Integer>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_user_selection);

    arrayOfIcons.clear();
    for (int i=0; i<3; i++) {arrayOfIcons.add(R.drawable.edit);}

    ArrayAdapter<Integer> adapter2 = new ArrayAdapter<Integer>(this, android.R.layout.simple_list_item_1, arrayOfIcons);
        ListView listView2 = (ListView) findViewById(R.id.usersListView2);
        listView2.setAdapter(adapter2);
        listView2.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                //TODO                    
            }
        });
    }
}

我没有在onResume方法中做任何事情，这就是为什么我没有共享它

还有我的xml文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">


<ListView
    android:id="@+id/usersListView2"
    android:layout_width="80dp"
    android:layout_height="450dp"
    android:layout_alignParentEnd="true"
    android:paddingTop="4dip"
    android:paddingBottom="3dip" />

</RelativeLayout>

Answer 1

嗨，我建议您创建一个自定义适配器：

1）创建您的list_item：

在res->布局中，创建一个名为 list_item.xml 的新文件。它只包含一个插入ConstraintLayout的imageView：

extern const int kDefaultOrderAccuracy;

2）在您的 activity_main.xml 中，您必须插入listView：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent">

<ImageView
    android:id="@+id/imageViewIcon"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.0"
    app:srcCompat="@mipmap/ic_launcher" />

3）现在，您必须创建一个新的类调用，例如 IconAdapter ，在其中创建您的自定义适配器：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">

<ListView
    android:id="@+id/listViewIcon"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginBottom="8dp"
    android:layout_marginTop="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

4）现在在您的 MainActivity 中，将所有内容放在一起：D

    public class IconAdapter extends BaseAdapter {

    Context context;
    List<Integer> iconIDList;

    /**
     *
     * @param context = activity context
     * @param iconIDList = list with icon's id
     */
    public IconAdapter(Context context, List<Integer> iconIDList) {
        this.context = context;
        this.iconIDList = iconIDList;
    }

    @Override
    public int getCount() {
        //return the size of my list
        return iconIDList.size();
    }

    @Override
    public Object getItem(int i) {
        return null;
    }

    @Override
    public long getItemId(int i) {
        return 0;
    }



    @Override
    public View getView(int i, View convertView, ViewGroup viewGroup) {

        //inflate my view
        if (convertView == null) {
            LayoutInflater inflater;
            inflater = LayoutInflater.from(context);
            convertView = inflater.inflate(R.layout.list_item, null);
        }

        //istantiate my imageView
        ImageView imageView = convertView.findViewById(R.id.imageViewIcon);

        //set imageView's icon
        imageView.setImageResource(iconIDList.get(i));

        //return my view
        return convertView;
    }
}

希望能对您有所帮助！！！做得好！！如果您有任何疑问，请评论我的答案！

Answer 2

在您的评论中，您问我如何为单击的名称（textView）添加一个侦听器，并为单击的图标添加一个侦听器。

1）修改您的 list_item.xml 文件。现在我们可以使用：

使用LinearLayout代替ConstraintLayout；
一个textView;

一个ImageButton而不是ImageView。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:descendantFocusability="blocksDescendants" > <!--this is very important to detect click-->

<TextView
    android:id="@+id/textViewIcon"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="3"
    android:gravity="left|center"
    android:text="TextView"
    android:textSize="24sp" />

<ImageButton
    android:id="@+id/imageButtonIcon"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dp"
    android:layout_weight="1"
    app:srcCompat="@mipmap/ic_launcher" />

</LinearLayout>

2）如果创建一个包含数据的类，那就更好了。我们可以将此类称为 IconData ：

    public class IconData {

    int iconID;
    String text;

    //constructor
    public IconData(int iconID, String text) {
        this.iconID = iconID;
        this.text = text;
    }

    //getter and setter
    public int getIconID() {
        return iconID;
    }

    public void setIconID(int iconID) {
        this.iconID = iconID;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

}

3）现在我们必须更改我们的 IconAdapter 。

我们将添加一个界面来检测对ImageButton的点击；
我们将更改列表的数据类型；

我们将实例化最新的TextView和ImageButton：

//create custom adapter -> I extend my class using BaseAdapter
public class IconAdapter extends BaseAdapter {

//create an interface to comunicate the clicks on the imageButton
public interface MyIconAdapterInterface {
    void setOnClickListnerMyImageButton (int position);
}

Context context;
//change the list's name and data type
List<IconData> iconIDTextList;
MyIconAdapterInterface myIconAdapterInterface;

/**
 * @param context = activity context
 * @param iconIDTextList = list with icon's id and text
 * @param myIconAdapterInterface = the interface that mainActivity will implements
 */
public IconAdapter(Context context, List<IconData> iconIDTextList, MyIconAdapterInterface myIconAdapterInterface) {
    this.context = context;
    this.iconIDTextList = iconIDTextList;
    this.myIconAdapterInterface = myIconAdapterInterface;
}

@Override
public int getCount() {
    //return the size of my list
    return iconIDTextList.size();
}

@Override
public Object getItem(int i) {
    return null;
}

@Override
public long getItemId(int i) {
    return 0;
}



@Override
public View getView(final int i, View convertView, ViewGroup viewGroup) {

    //inflate my view
    if (convertView == null) {
        LayoutInflater inflater;
        inflater = LayoutInflater.from(context);
        convertView = inflater.inflate(R.layout.list_item, null);
    }

    //istantiate my imageView and textView
    ImageButton imageButton = convertView.findViewById(R.id.imageButtonIcon);
    TextView textView = convertView.findViewById(R.id.textViewIcon);

    //set imageView's button
    int image = iconIDTextList.get(i).getIconID();
    imageButton.setImageResource(image);

    //set text
    String text = iconIDTextList.get(i).getText();
    textView.setText(text);

    //setOnclickListner on my imageButton
    imageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //pass the position of my clicks to the myIconAdapterInterface
            myIconAdapterInterface.setOnClickListnerMyImageButton(i);

        }
    });

    return convertView;
}

}

4）最后，我们必须更改 MainActivity.java 的代码：

使用我们在IconAdapter中创建的新接口来实现我们的类；
修改我们的列表数据类型；
将最新列表和接口传递给IconAdapter；

实现接口的方法。

//I implement my MainActivity with IconAdapter.MyIconAdapterInterface. I create this interface
//in the iconAdapter class 
public class MainActivity extends AppCompatActivity implements IconAdapter.MyIconAdapterInterface {

//change to iconIDTextList and change List data type
List<IconData> iconIDTextList;
IconAdapter iconAdapter;
ListView listView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //istantiate my components
    iconIDTextList = new ArrayList<>();
    listView = findViewById(R.id.listViewIcon);
    //the second "this" is refer to the IconAdapter.MyIconAdapterInterface
    iconAdapter = new IconAdapter(this, iconIDTextList, this);
    int myIcon = R.drawable.ic_launcher_background;
    String myText = "Hello! ";

    //populate the list with icon's id and text
    for (int i = 0; i < 5; i++) {
        iconIDTextList.add(new IconData(myIcon, myText + i));
    }

    //set my custom adapter to the listView
    listView.setAdapter(iconAdapter);

    //set clickListner to the elements of my listView
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

            //i is the index of the clicked element
            Toast.makeText(MainActivity.this, "Click on element n. " + i, Toast.LENGTH_SHORT).show();

        }
    });

}

//this is IconAdapter.MyIconAdapterInterface's method that I have to implement
@Override
public void setOnClickListnerMyImageButton(int position) {

    //position = click's position
    Toast.makeText(this, "Click on image n. "
             + position, Toast.LENGTH_SHORT).show();

}

}

干得好！

在列表视图中无法正确打印Drawable

2 个答案: