Question

我希望在ListView中有渐变背景的行，我希望它们在按下时更改为纯色。但我无法做到对。我知道ListViews有的问题，我在其他主题中阅读了一些解决方案，但它们似乎都不适合我。任何帮助都会很棒。

当我运行以下代码时，我得到的图像没问题： Before pressed

但是当我按下第2项时，所有行都将变为绿色！： after pressed

这是我的适配器：

public class MyAdapter extends BaseAdapter {

    private final Context mContext;
    private ArrayList<String> mMenuItems;

    StateListDrawable mBackgroundDrawable;

    public MyAdapter(Context context) {

        this.mContext = context;

        mMenuItems= new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            mMenuItems.add(String.format("Item %d", i));
        }

        // make background drawable
        GradientDrawable backgroundDrawable = new GradientDrawable(
                GradientDrawable.Orientation.TOP_BOTTOM,
                new int[]{  Color.RED, Color.YELLOW, Color.RED});
        backgroundDrawable.setCornerRadius(0f);

        ColorDrawable selectedColorDrawable= new ColorDrawable(Color.GREEN);

        mBackgroundDrawable = new StateListDrawable();
        mBackgroundDrawable.addState(new int[] {android.R.attr.state_pressed}, selectedColorDrawable);
        mBackgroundDrawable.addState(new int[] {android.R.attr.state_focused}, selectedColorDrawable);
        mBackgroundDrawable.addState(new int[] {android.R.attr.state_selected}, selectedColorDrawable);
        mBackgroundDrawable.addState(new int[] {}, backgroundDrawable);
    }

    @Override
    public int getCount() {
        return mMenuItems.size();
    }

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewGroup item = getViewGroup(convertView);
        if (Build.VERSION.SDK_INT<Build.VERSION_CODES.JELLY_BEAN) {
            item.setBackgroundDrawable(mBackgroundDrawable);
        } else {
            item.setBackground(mBackgroundDrawable);
        }
        // set title
        TextView titleView= (TextView) item.findViewById(R.id.menu_title);
        titleView.setText(mMenuItems.get(position));
        return item;
    }

    public ViewGroup getViewGroup(View reuse)
    {
        if(reuse instanceof ViewGroup)
            return (ViewGroup)reuse;

        LayoutInflater inflater = LayoutInflater.from(mContext);
        ViewGroup item = (ViewGroup)inflater.inflate(R.layout.row_menu, null);

        return item;
    }
}

我的row_menu.xml：

<?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="wrap_content"
    android:padding="5dp">

    <TextView
        android:id="@+id/menu_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"/>

</RelativeLayout>

我的活动布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp">

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

我的活动：

public class MainActivity extends ActionBarActivity{

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

        ListView list = (ListView) findViewById(R.id.activity_main_listview);
        list.setAdapter(new MyAdapter(this));
    }
}

Answer 1

mBackgroundDrawable对于所有行都很常见。您需要将唯一的mBackgroundDrawable附加到每一行（例如，在您添加它的循环内）。这非常简单，但随意询问您是否需要一个具体的例子！ ;）

Answer 2

你可以通过XML自己实现它。

的ListView

<ListView
        android:id="@+id/list_slidermenu"
        android:layout_width="240dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:choiceMode="singleChoice"
        android:divider="@color/list_divider"
        android:dividerHeight="1dp"       
        android:listSelector="@drawable/list_selector"
        android:background="@color/list_background"/>

可绘/ list_selector.xml

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

    <item android:drawable="@drawable/list_item_bg_normal" android:state_activated="false"/>
    <item android:drawable="@drawable/list_item_bg_pressed" android:state_pressed="true"/>
    <item android:drawable="@drawable/list_item_bg_pressed" android:state_activated="true"/>

</selector>

可绘/ list_item_bg_pressed.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
  <gradient
      android:startColor="@color/list_background_pressed"
      android:endColor="@color/list_background_pressed"
      android:angle="90" />
</shape>

可绘/ list_item_bg_normal.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
  <gradient
      android:startColor="@color/list_background"
      android:endColor="@color/list_background"
      android:angle="90" />
</shape>

正如您所看到的，ListView有一个名为android：listSelector的attr，它的值是“@ drawable / list_selector”。这是我们设置选择器的地方。我认为其余的都是自我解释。

如果您需要更多说明，请阅读此http://javatechig.com/android/android-listview-tutorial

ListView行按下了渐变背景的颜色

2 个答案: