Question

我几乎没有开发Android应用程序的经验。我的朋友让我为他的应用程序创建一个小功能。我所坚持的是为选项创建一个子菜单，即我有它，以便当点击一个按钮时会弹出一个菜单，其中包含一些选项，我需要它在单击特定选项时打开第二个菜单。我将在下面发布我的代码（包括XML和Java），希望有人可以帮助我。目前我的菜单显示的是Java代码，而不是XML代码。我不确定这是不是坏习惯，但我会让任何可以帮助我的人告诉我它是否是。提前谢谢。

XML代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main"
    tools:context="com.example.android.postvu.MainActivity">

<ImageView
    android:id="@+id/imageView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:contentDescription="@string/background"
    android:scaleType="centerCrop"
    android:src="@drawable/grid" />

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginTop="8dp"
    android:text="@string/image_text_editor"
    android:textColor="@android:color/black"
    android:textSize="28sp"
    android:textStyle="bold"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:text="Image Text Editor" />


<Button
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_marginBottom="8dp"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginTop="8dp"
    android:background="@mipmap/ic_launcher"
    android:scaleType="centerCrop"
    android:onClick="myOnClickMethod"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView"
    app:layout_constraintVertical_bias="0.98" />

Java代码（与点击的按钮和显示的菜单有关）：

public void myOnClickMethod(View v) {
    registerForContextMenu(v);
    openContextMenu(v);
}

final int CONTEXT_MENU_VIEW = 1;
final int CONTEXT_MENU_EDIT = 2;
final int CONTEXT_MENU_ARCHIVE = 3;


@Override
public void onCreateContextMenu (ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
    menu.setHeaderTitle("Options");
    menu.add(Menu.NONE, CONTEXT_MENU_VIEW, Menu.NONE, "Take Photo");
    menu.add(Menu.NONE, CONTEXT_MENU_EDIT, Menu.NONE, "Photo Album");
    menu.add(Menu.NONE, CONTEXT_MENU_ARCHIVE, Menu.NONE, "Plain Image");
}

@Override
public boolean onContextItemSelected (MenuItem item) {
    switch (item.getItemId()) {
        case CONTEXT_MENU_VIEW: {
        }
        break;
        case CONTEXT_MENU_EDIT: {
        }
        break;
        case CONTEXT_MENU_ARCHIVE: {
        }
        break;
    }

    return super.onContextItemSelected(item);
}

Answer 1

您可以通过以下方式显示子菜单。我修改了你的代码并使用了硬编码常量。我希望这会对你有所帮助。

public class MainActivity extends AppCompatActivity {
    private View menuAnchorView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        menuAnchorView = findViewById(R.id.imageView2);
        menuAnchorView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                myOnClickMethod(menuAnchorView);
            }
        });
    }

    public void myOnClickMethod(View v) {
        registerForContextMenu(v);
        openContextMenu(v);
    }

    final int CONTEXT_MENU_VIEW = 1;
    final int CONTEXT_MENU_EDIT = 2;
    final int CONTEXT_MENU_ARCHIVE = 3;


    @Override
    public void onCreateContextMenu (ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        if(v.getTag() == null || !v.getTag().equals("menu_item")) {
            menu.setHeaderTitle("Options");
            menu.add(Menu.NONE, CONTEXT_MENU_VIEW, Menu.NONE, "Take Photo");
            menu.add(Menu.NONE, CONTEXT_MENU_EDIT, Menu.NONE, "Photo Album");
            menu.add(Menu.NONE, CONTEXT_MENU_ARCHIVE, Menu.NONE, "Plain Image");
        }
        else {
            menu.setHeaderTitle("Sub menu");
            menu.add(Menu.NONE, 4, Menu.NONE, "Sub-view");
            menu.add(Menu.NONE, 5, Menu.NONE, "Sub-view-2");
        }
    }

    @Override
    public boolean onContextItemSelected (MenuItem item) {
        closeContextMenu();
        switch (item.getItemId()) {
            case CONTEXT_MENU_VIEW: {
                menuAnchorView.setTag("menu_item");
                openContextMenu(menuAnchorView);
            }
            break;
            case CONTEXT_MENU_EDIT: {
            }
            break;
            case CONTEXT_MENU_ARCHIVE: {
            }
            break;
            case 4:
            case 5: menuAnchorView.setTag(null);
                break;
        }

        return super.onContextItemSelected(item);
    }

}

在android

1 个答案: