android studio ListView使用

class
参考书籍《第一行代码》

Fruit适配器

public class FruitAdapter extends ArrayAdapter {

    private int resourceId;

    public FruitAdapter(@NonNull Context context, int textViewResourceId, List<Fruit> objects) {

        super(context,textViewResourceId,objects);
        this.resourceId = textViewResourceId;

    }

    class ViewHolder{

        TextView fruitText;
        ImageView fruitImage;

    }

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

        Fruit fruit = (Fruit)getItem(position);
        View view;
        ViewHolder viewHolder;

        /*

           convertView可以将之前的布局进行缓存 因此只要第一次存储 之后直接用即可

         */
        if(convertView == null ){

            /*
                如果是空的 那么说明convertView还没有加载

                加载动态布局
             */
            view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = view.findViewById(R.id.fruit_image);
            viewHolder.fruitText  = view.findViewById(R.id.fruit_text);
            view.setTag(viewHolder);     //将viewHolder存进view中

        }
        else{

            view = convertView;   //从这里取出
            viewHolder = (ViewHolder) view.getTag();

        }
        //设置显示的数据
        viewHolder.fruitText.setText(fruit.getFruitName());
        viewHolder.fruitImage.setImageResource(fruit.getFruitImageId());

        return view;
    }
}

 MainActivity

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //初始化fruitList数据
        initFruit();

        ListView listView = findViewById(R.id.listView);

        TextView weChat = findViewById(R.id.title_text);

        weChat.setText("微信("+fruitList.size()+")");

        FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_layout,fruitList);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                //获得该行在ArrayList的fruit数据
                Fruit fruit = fruitList.get(position);
                //显示出来
                Toast.makeText(MainActivity.this,fruit.getFruitName(),Toast.LENGTH_SHORT).show();
            }
        });

        
        ActionBar actionBar = getSupportActionBar();

        if(actionBar !=null){

           actionBar.hide();//隐藏标题栏
        }

        listView.setAdapter(adapter);//设置好适配器
        
    }

    public void initFruit(){

        for(int i =0;i<2;i++){

            
            //加载已经存储好的图片
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );
            fruitList.add( new Fruit(R.mipmap.orange,"橙子") );

        }

    }

}

	Fruit

public class Fruit {

    private int fruitImageId;
    private String fruitName;

    public int getFruitImageId(){

        return this.fruitImageId;
    }

    public String getFruitName(){

        return this.fruitName;
    }

    public Fruit(int fruitImageId,String fruitName){

        this.fruitImageId =fruitImageId;
        this.fruitName    = fruitName;

    }

}

layout

fruitLayout  显示的表单内容

<?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">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/fruit_text"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

创建的ListView对象

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

    <include layout="@layout/title_layout"/>

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

自定义的标题栏

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:background="#DCDCDC"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/title_text"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="45dp"
        android:background="#DCDCDC"
        android:text="微信"
        android:layout_marginLeft="10dp"
        android:gravity="center|left"
        android:textColor="#000000"
        android:textSize="15sp"/>

    <Button
        android:layout_width="45dp"
        android:layout_height="45dp"
        android:background="#DCDCDC"
        android:textColor="#000000"
        android:text = "🔍" />

    <Button

        android:layout_width="45dp"
        android:layout_height="45dp"
        android:textColor="#000000"
        android:text=". . ." />


</LinearLayout>

效果