Question

我的应用有问题，其中包含2个片段布局当我想从抽屉项目单击同时更改两个片段的它给我这样的错误

2019-06-04 22:22:03.572 24088-24088/com.example.android.madbaloon3 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android.madbaloon3, PID: 24088
    java.lang.IllegalStateException: commit already called
        at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:669)
        at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:637)
        at com.example.android.madbaloon3.MainActivity.onNavigationItemSelected(MainActivity.java:195)
        at android.support.design.widget.NavigationView$1.onMenuItemSelected(NavigationView.java:170)
        at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:840)
        at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
        at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:991)
        at android.support.design.internal.NavigationMenuPresenter$1.onClick(NavigationMenuPresenter.java:352)
        at android.view.View.performClick(View.java:6261)
        at android.view.View$PerformClick.run(View.java:23752)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6776)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)

首先，我在课堂上设置片段内容


    private MapFragment mapFragment = new MapFragment();
    private DataFragment dataFragment = new DataFragment();
    private InfoFragment infoFragment = new InfoFragment();
    private AboutFragment aboutFragment = new AboutFragment();
    private EmptyFragment emptyFragment = new EmptyFragment();


private FragmentTransaction transaction_top = getSupportFragmentManager().beginTransaction();
private FragmentTransaction transaction_bottom = getSupportFragmentManager().beginTransaction();

然后在oncreate中，我会像这样设置默认片段

transaction_bottom.replace(R.id.bottomFragment, dataFragment);
        transaction_bottom.commit();
        bottom_fragment_name="dataFragment";


        transaction_top.replace(R.id.topFragment, mapFragment);
        transaction_top.commit();
        top_fragment_name="mapFragment";

然后我想在有人点击抽屉项目时更改两个片段

    @Override
    public boolean onNavigationItemSelected(MenuItem item) {


        switch (item.getItemId()) {
            case R.id.nav_map:

                transaction_top.replace(R.id.topFragment, mapFragment);
                transaction_top.commit();

                break;
            case R.id.nav_about:


                transaction_top.replace(R.id.topFragment,aboutFragment);
                transaction_top.commit();


                transaction_top.replace(R.id.bottomFragment,infoFragment);
                transaction_bottom.commit();


            default:
                break;

        }

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

片段整合（我的意思是content_main.xml）

        <FrameLayout
            android:id="@+id/topFragment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="25"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:layout="@layout/fragment_map" />

        <FrameLayout
            android:id="@+id/bottomFragment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:layout="@layout/fragment_info"
            />

我一直在尝试删除交易中的片段，然后再替换它，但是它不起作用

Answer 1

您的错误状态：

java.lang.IllegalStateException：提交已被调用

这意味着，您正在尝试在活动中的某个位置两次提交FragmentTransaction。

您将在onNavigationItemSelected的{{1}}中看到您已经编写了此代码。

case R.id.nav_about

在这种情况下，您之前已经提交了transaction_bottom，但是在这里您尝试再次进行操作而不对事务进行任何更改。所以您必须将其更改为

transaction_top.replace(R.id.bottomFragment,infoFragment);
transaction_bottom.commit();

Answer 2

java.lang.IllegalStateException：已调用被抛出，因为您已经提交了 transaction_top 并试图通过同一事务更改另一个片段。也许你打算写的是

 @Override
public boolean onNavigationItemSelected(MenuItem item) {

    FragmentTransaction transaction_top = getSupportFragmentManager().beginTransaction();
    FragmentTransaction transaction_bottom = getSupportFragmentManager().beginTransaction();

    switch (item.getItemId()) {
        case R.id.nav_map:

            transaction_top.replace(R.id.topFragment, mapFragment);
            transaction_top.commit();

            break;
        case R.id.nav_about:


            transaction_top.replace(R.id.topFragment,aboutFragment);
            transaction_top.commit();


            transaction_bottom.replace(R.id.bottomFragment,infoFragment);
            transaction_bottom.commit();


        default:
            break;

    }

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

请注意，每次调用 onNavigationSelected 函数时，都必须启动新的FragmentTransactions，因为您希望更改片段。

进一步说明，您不需要创建两个单独的FragmentTransaction对象 transaction_top 和 transaction_bottom ，您可以创建单个FragmentTransaction对象并更改其中的两个片段相同的交易如下

 @Override
public boolean onNavigationItemSelected(MenuItem item) {

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    switch (item.getItemId()) {
        case R.id.nav_map:

            transaction.replace(R.id.topFragment, mapFragment);
            transaction.commit();

            break;
        case R.id.nav_about:


            transaction.replace(R.id.topFragment,aboutFragment);
            transaction.replace(R.id.bottomFragment,infoFragment);
            transaction.commit();


        default:
            break;

    }

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

如何处理2个FragmentTransaction

2 个答案: