Question

我的问题与this类似。我在Skobbler map工作。我有MainActivity，其中包含HomeFragment。我的HomeFragement包含stack of view类似：A->B->C->D。当我到达view D时，如果我back press，那么我想回去：D->-C->B->A。

在我的MainActivity中，我在Fragment方法中添加了onCreate：

homeFragment = HomeFragment.newInstance();
    getSupportFragmentManager()
            .beginTransaction()
            .replace(R.id.llMainActivityContainer, homeFragment)
            .addToBackStack(TAG)
            .commit();

和

@Override
public void onBackPressed() {
    if (!homeFragment.onBackPressed()) {
        int count = getSupportFragmentManager().getBackStackEntryCount();
        if (count > 0) {
            getSupportFragmentManager().popBackStack();
            return;
        }
        super.onBackPressed();
    }
}

在我的HomeFragment中，我有onBackPress方法。

public boolean onBackPressed() {}

但是，我无法从final view返回first view as homescreen。我应该在这里包括什么？可以做些什么来解决这个问题？

添加代码

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/rlHomeContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:animateLayoutChanges="true">


<com.skobbler.ngx.map.SKMapViewHolder
    android:id="@+id/skmVHHome"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<RelativeLayout
    android:id="@+id/chess_board_background"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/map_background" />

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

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fabDrivingDirections"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/fabCurrentLoc"
    android:layout_alignParentRight="true"
    android:layout_marginBottom="16dp"
    android:layout_marginRight="@dimen/activity_horizontal_margin"
    app:backgroundTint="@color/blue_panel_day_background" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fabCurrentLoc"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:layout_marginBottom="150dp"
    android:layout_marginRight="@dimen/activity_horizontal_margin"
    app:backgroundTint="@color/blue_panel_day_background" />


<include
    layout="@layout/layout_drive_info"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true" />


</RelativeLayout>

Answer 1

在设计平板电脑的片段类时，感觉Google错过了这一部分。片段可能对处理后退按钮感兴趣，但是他们没有收到任何类型的回调，让他们知道按下后退按钮。

这就是我解决这个问题的方法。

定义界面。我这样做是活动的内部接口，因为它是访问实现它的客户端的活动。

    public interface HandlesOnBackPressed {

        /**
         * Callback for back button pressed event.
         * @return true if the back press was handled so the activity doesn't need to.
         */
        boolean onBackPressed();
    }

对后退按钮感兴趣的片段将实现此接口

public class MyFragment extends Fragment implements MyActivity.HandlesOnBackPressed {

    ...

    @Override
    public boolean onBackPressed() {

        ...

执行片段事务时：
1. 执行交易时HandlesOnBackPressed片段为replace片段提供唯一标记（MyFragment fragment = MyFragment.newInstance(... fragmentManager .beginTransaction() .replace(R.id.fragment_container, fragment, "MyFragment") .addToBackStack("MyFragment") .commit();等。）
2. 当您将事务推送到后台堆栈时，请将该堆栈条目指定为相同的标记。
```
onBackPressed
```
3. 这是秘密酱。覆盖活动中的@Override public void onBackPressed() { FragmentManager fragmentManager = getSupportFragmentManager(); int count = fragmentManager.getBackStackEntryCount(); if (count > 0) { FragmentManager.BackStackEntry topBackStackEntry = fragmentManager.getBackStackEntryAt(count - 1); if (topBackStackEntry != null) { String tag = topBackStackEntry.getName(); if (tag != null) { // since super.onBackPressed() hasn't been called yet, // the top back stack entry should match with the current fragment Fragment fragment = fragmentManager.findFragmentByTag(tag); if (fragment instanceof HandlesOnBackPressed) { if (((HandlesOnBackPressed) fragment).onBackPressed()) { // the fragment handled the back press, // so don't call super.onBackPressed() return; } } } } } DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); if (drawerLayout != null && drawerLayout.isDrawerOpen(GravityCompat.START)) { drawerLayout.closeDrawer(GravityCompat.START); } else { super.onBackPressed(); // pops back stack, onBackStackChanged() is called } }：
```
{{1}}
```

谷歌，你为什么要让我这样做呢？

返回按片段中的视图

1 个答案: