Lung-Yu,Tsai 的部落格

應用情境

有多筆相同樣式之資料，希望能夠以條列式的方式呈現給使用者觀看。

目標成果

先將Item的行為提取成介面(interface)。透過"Adapter Pattern",將實作IItem 介面之物件轉換給 「UI Containers」。程式處理邏輯如下圖所示。

Layout

activity_main.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="wrap_content"
    android:orientation="vertical">
    <TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtTitle"
        android:layout_weight="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Large" />
    <TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtDetail"
        android:layout_weight="1" />
</LinearLayout>

item.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="wrap_content"
    android:orientation="vertical">
    <TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtTitle"
        android:layout_weight="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Large" />
    <TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtDetail"
        android:layout_weight="1" />
</LinearLayout>

Java Code

AbstractAdapter.java

public class AbstractAdapter extends BaseAdapter {
    private Context context;
    private LayoutInflater inflater;
    private List<IItem> items;
    private int count = 0;

    public AbstractAdapter(Context context, List<IItem> datasource){
        this.context = context;
        inflater = ((LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE));
        this.items = datasource;
    }

    @Override
    public int getCount() {
        if (items != null)
            return items.size();
        return 0;
    }

    @Override
    public Object getItem(int position) {
        return items.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = inflater.inflate(items.get(position).getLayoutId(), null);
        }

        IItem item = items.get(position);
        item.initView(position, convertView, parent);
        return convertView;
    }
}

ItemMessage.java

public class ItemMessage implements IItem {

    private String title;
    private String detail;
    public ItemMessage(String title,String detail){
        this.title = title;
        this.detail = detail;
    }


    @Override
    public void initView(int position, View view, ViewGroup parent) {
        TextView txtTitle = (TextView) view.findViewById(R.id.txtTitle);
        TextView txtDetail = (TextView) view.findViewById(R.id.txtDetail);

        txtTitle.setText(title);
        txtDetail.setText(detail);
    }

    @Override
    public int getLayoutId() {
        return R.layout.item_view;
    }

    @Override
    public void release() {

    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private List<IItem> datasource = new ArrayList<IItem>();
    private Context context = this;
    private ListView listView;

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

        //view binding
        listView = (ListView) findViewById(R.id.listview1);

        //set resouce
        getDatasource();
        AbstractAdapter adapter = new AbstractAdapter(context,datasource);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(onItemClickListener);
    }

    private void getDatasource(){
        datasource.add(new ItemMessage("鉛筆","20"));
        datasource.add(new ItemMessage("原子筆","30"));
        datasource.add(new ItemMessage("鋼筆","10"));
        datasource.add(new ItemMessage("毛筆","1"));
        datasource.add(new ItemMessage("彩色筆","24"));
    }

    private AdapterView.OnItemClickListener onItemClickListener = new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Toast.makeText(context,"Select " + position,Toast.LENGTH_SHORT).show();
        }
    };

}

完整程式碼 : https://github.com/Lung-Yu/AndroidApps/tree/master/Containers/ListView