在Android中使用ListView自定义ArrayAdapter

在上一篇带有Example的Android中的ArrayAdapter文章中，已经讨论了ArrayAdapter的工作方式以及可以使用ListView附加到ArrayAdapter的数据源是什么。在本文中，已经讨论了如何使用ListView实现自定义ArrayAdapter。请看以下图像，其中可以自定义ArrayAdapter中的单个视图。

实现自定义ArrayAdapter的步骤

步骤1：创建一个空活动项目

• 创建一个空活动的Android Studio项目。参考Android |如何在Android Studio中创建/启动新项目?
• 并确保选择Java编程。

步骤2：使用activity_main.xml

• 在activity_main.xml文件中，根视图是ListView。将以下代码调用到activity_main.xml文件中，并提及ListView的适当ID。

步骤3：为ListView创建自定义视图

• 在布局下，该文件夹将创建一个布局为custom_list_view.xml并调用以下代码。

• 对于ListView中的每个单个项目，此布局为阵列适配器中的每个单个项目创建以下视图。

步骤4：为自定义布局创建一个自定义类

• 通过创建此自定义类，我们可以为custom_list_view布局手动调用getter和setter。
• 在应用程序的包文件夹下创建一个名为NumbersView的自定义类。
• 并调用以下代码。

Java

public class NumbersView {
  
    // the resource ID for the imageView
    private int ivNumbersImageId;
  
    // TextView 1
    private String mNumberInDigit;
  
    // TextView 1
    private String mNumbersInText;
  
    // create constructor to set the values for all the parameters of the each single view
    public NumbersView(int NumbersImageId, String NumbersInDigit, String NumbersInText) {
        ivNumbersImageId = NumbersImageId;
        mNumberInDigit = NumbersInDigit;
        mNumbersInText = NumbersInText;
    }
  
    // getter method for returning the ID of the imageview
    public int getNumbersImageId() {
        return ivNumbersImageId;
    }
  
    // getter method for returning the ID of the TextView 1
    public String getNumberInDigit() {
        return mNumberInDigit;
    }
  
    // getter method for returning the ID of the TextView 2
    public String getNumbersInText() {
        return mNumbersInText;
    }
}

步骤5：现在创建一个NumbersView类型的自定义ArrayAdapter类

• 在相同的程序包名称下，创建一个NumbersViewAdapter。 NumbersView类型的Java类，它扩展了ArrayAdapter类。
• 并在NumbersViewAdapter内部调用以下代码。 Java文件。添加了注释以便更好地理解。

Java

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.util.ArrayList;
  
public class NumbersViewAdapter extends ArrayAdapter {
  
    // invoke the suitable constructor of the ArrayAdapter class
    public NumbersViewAdapter(@NonNull Context context, ArrayList arrayList) {
        
          // pass the context and arrayList for the super 
          // constructor of the ArrayAdapter class
        super(context, 0, arrayList);
    }
  
    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
  
        // convertView which is recyclable view
        View currentItemView = convertView;
  
        // of the recyclable view is null then inflate the custom layout for the same
        if (currentItemView == null) {
            currentItemView = LayoutInflater.from(getContext()).inflate(R.layout.custom_list_view, parent, false);
        }
  
        // get the position of the view from the ArrayAdapter
        NumbersView currentNumberPosition = getItem(position);
  
        // then according to the position of the view assign the desired image for the same
        ImageView numbersImage = currentItemView.findViewById(R.id.imageView);
        assert currentNumberPosition != null;
        numbersImage.setImageResource(currentNumberPosition.getNumbersImageId());
  
        // then according to the position of the view assign the desired TextView 1 for the same
        TextView textView1 = currentItemView.findViewById(R.id.textView1);
        textView1.setText(currentNumberPosition.getNumberInDigit());
  
        // then according to the position of the view assign the desired TextView 2 for the same
        TextView textView2 = currentItemView.findViewById(R.id.textView2);
        textView2.setText(currentNumberPosition.getNumbersInText());
  
        // then return the recyclable view
        return currentItemView;
    }
}

步骤6：使用MainActivity。 Java文件

• 在这种情况下，需要为所有项目创建一个自定义ArrayList，其中包括ImageView的Image，TextView 1的Text，TextView 2的Text。

Java

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import java.util.ArrayList;
  
public class MainActivity extends AppCompatActivity {
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
  
        // create a arraylist of the type NumbersView
        final ArrayList arrayList = new ArrayList();
  
        // add all the values from 1 to 15 to the arrayList
        // the items are of the type NumbersView
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "1", "One"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "2", "Two"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "3", "Three"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "4", "Four"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "5", "Five"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "6", "Six"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "7", "Seven"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "8", "Eight"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "9", "Nine"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "10", "Ten"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "11", "Eleven"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "12", "Twelve"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "13", "Thirteen"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "14", "Fourteen"));
        arrayList.add(new NumbersView(R.drawable.geeks_logo, "15", "Fifteen"));
  
        // Now create the instance of the NumebrsViewAdapter and pass 
          // the context and arrayList created above
        NumbersViewAdapter numbersArrayAdapter = new NumbersViewAdapter(this, arrayList);
  
        // create the instance of the ListView to set the numbersViewAdapter
        ListView numbersListView = findViewById(R.id.listView);
  
        // set the numbersViewAdapter for ListView
        numbersListView.setAdapter(numbersArrayAdapter);
    }
}

输出：在模拟器上运行

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