OnClick 的另一种书写

原创

木子杂志

修改于 2020-08-04 01:55:37

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文章被收录于专栏：木子杂志木子杂志

前言

在自定义 View 时,每个 view 里面一般都会写一次 OnClick 事件

今天使用另外一种方式将点击事件从我们的 activity 或者自定义 View 中抽取出来

利于 java8 中一个特性双冒号:: 关键字

:: 关键字

java 8 中:: 关键字可以用来引用类的方法

利于这一点我们用另一个风格写一下 android 中的点击事件

另一种方式书写 OnClick

public class ItemClickHandler {

    public static final View.OnClickListener INSTANCE = ItemClickHandler::onItemClick;

    private static void onItemClick(View v) {

        switch (v.getId()) {
            case R.id.btn_1:
                Toast.makeText(v.getContext().getApplicationContext(), "button1", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_2:
                Toast.makeText(v.getContext().getApplicationContext(), "button2", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_3:
                Toast.makeText(v.getContext().getApplicationContext(), "button2", Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }
    }

}

这样我们就可以实现在一个地方定义,别处使用

public class TestActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        findViewById(R.id.btn_1).setOnClickListener(ItemClickHandler.INSTANCE);

    }
}

public class NavigationView extends RelativeLayout {

    protected void bindClick() {
        findViewById(R.id.btn_2).setOnClickListener(ItemClickHandler.INSTANCE);
    }
}


public class BottomView extends RelativeLayout {

    protected void bindClick() {
        findViewById(R.id.btn_3).setOnClickListener(ItemClickHandler.INSTANCE);
    }
}

出处

【packages/apps/Launcher3/src/com/android/launcher3/touch/ItemClickHandler.java】

【---> ItemClickHandler.java】

/**
 * Class for handling clicks on workspace and all-apps items
 */
public class ItemClickHandler {

    /**
     * Instance used for click handling on items
     */
    public static final OnClickListener INSTANCE = ItemClickHandler::onClick;

    //点击事件
    private static void onClick(View v) {
        // Make sure that rogue clicks don't get through while allapps is launching, or after the
        // view has detached (it's possible for this to happen if the view is removed mid touch).
        if (v.getWindowToken() == null) {
            return;
        }

        Launcher launcher = Launcher.getLauncher(v.getContext());
        if (!launcher.getWorkspace().isFinishedSwitchingState()) {
            return;
        }

        Object tag = v.getTag();
        if (tag instanceof ShortcutInfo) {
            onClickAppShortcut(v, (ShortcutInfo) tag, launcher);
        } else if (tag instanceof FolderInfo) {
            if (v instanceof FolderIcon) {
                onClickFolderIcon(v);
            }
        } else if (tag instanceof AppInfo) {
            //点击 icon 启动应用
            startAppShortcutOrInfoActivity(v, (AppInfo) tag, launcher);
        } else if (tag instanceof LauncherAppWidgetInfo) {
            if (v instanceof PendingAppWidgetHostView) {
                onClickPendingWidget((PendingAppWidgetHostView) v, launcher);
            }
        }
    }
  //...
}