android - 通过activity访问fragment方法

Question

我正在开发一个自助服务终端应用程序，人们可以步行前往并点餐。

我有一个包含许多不同 fragment (订购、评论、支付等)的 Activity 。有的相互替代，有的相互补充。该 Activity 有一个硬编码的 fragment R.id.fragmentContainer，其余 fragment 以编程方式添加和标记。

现在我想要的是在我的 Activity 中有一个调用 fragment 元素之一的函数(查看 updateReceivedData())但由于某些原因我无法这样做我得到 cannot resolve method adjustPriceFunc。

我正在添加代码，以便有人可以告诉我我做错了什么。该应用程序通常会与某些硬件对话，因此我从代码中删除了一些细节以使其更易于阅读。

public class MainActivity extends FragmentActivity {
private final String TAG = MainActivity.class.getSimpleName();

List<WeakReference<Fragment>> fragList = new ArrayList<WeakReference<Fragment>>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    Log.d(TAG, "onCreate()");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.backbone);
    android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
    android.support.v4.app.Fragment fragment = fm.findFragmentById(R.id.fragmentContainer);

    if (fragment == null) {
        fragment = new Fragment();
        fm.beginTransaction()
                .add(R.id.fragmentContainer, fragment, "SystemDownFragment")
                .addToBackStack(null)
                .commit();
    }
}

public void orderFunc() {
    Log.d(TAG, "orderFunc()");
    if(sendingLogFlag)      attemptSend(TAG + ":orderFunc()");

    for(int i = 0; i < getActiveFragments().size(); i++) {
        getSupportFragmentManager().beginTransaction().remove(getActiveFragments().get(i)).commit();
    }

    Fragment newFragment = new Fragment();
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.add(R.id.fragmentContainer, newFragment, "OrderFragment");
    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
    ft.commit();
}

public void checkoutFunc() {
    Log.d(TAG, "checkoutFunc()");
    if(sendingLogFlag)      attemptSend(TAG + ":checkoutFunc()");

    for(int i = 0; i < getActiveFragments().size(); i++) {
        getSupportFragmentManager().beginTransaction().remove(getActiveFragments().get(i)).commit();
    }

    Fragment newFragment = new Fragment();
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.add(R.id.fragmentContainer, newFragment, "CheckOutFragment");
    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
    ft.commit();
}

public void reviewFunc(){
    Log.d(TAG, "reviewFunc()");
    if(sendingLogFlag)      attemptSend(TAG + ":reviewFunc()");

    if(getActiveFragments().size() > 1){
        Fragment frag = getSupportFragmentManager().findFragmentByTag("ReviewFragment");
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
        ft.remove(frag);
        ft.commit();
    }
    else {
        Fragment newFragment = new Fragment();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        ft.add(R.id.fragmentContainer, newFragment, "ReviewFragment");
        ft.commit();
    }
    getSupportFragmentManager().executePendingTransactions();
}

public void payFunc(boolean enabled){
    Log.d(TAG, "payFunc()");
    if(sendingLogFlag)      attemptSend(TAG + ":payFunc()");

    if(!enabled){
        Fragment frag = getSupportFragmentManager().findFragmentByTag("PayFragment");
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
        ft.remove(frag);
        ft.commit();
    }
    else {
        Fragment newFragment = new Fragment();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        ft.add(R.id.fragmentContainer, newFragment, "PayFragment");
        ft.commit();
    }
    getSupportFragmentManager().executePendingTransactions();
}

public void doneFunc() {
    Log.d(TAG, "doneFunc()");

    for(int i = 0; i < getActiveFragments().size(); i++) {
        getSupportFragmentManager().beginTransaction().remove(getActiveFragments().get(i)).commit();
    }

    Fragment newFragment = new Fragment();
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
    ft.add(R.id.fragmentContainer, newFragment, "StartupFragment");
    ft.commit();
}

@Override
public void onAttachFragment (Fragment fragment) {
    fragList.add(new WeakReference(fragment));
}

public List<Fragment> getActiveFragments() {
    ArrayList<Fragment> ret = new ArrayList<Fragment>();
    for(WeakReference<Fragment> ref : fragList) {
        Fragment f = ref.get();
        if(f != null) {
            if(f.isVisible()) {
                ret.add(f);
            }
        }
    }
    return ret;
}

private void updateReceivedData() {
    Fragment frag = getSupportFragmentManager().findFragmentByTag("PayFragment");
                        frag.adjustPriceFunc();
}

Answer 1

您正在尝试使用类 Fragment 中的方法 adjustPriceFunc()，这不是它的一部分。

使用此代码，其中 MyFragment 是您的正确 fragment (我认为它应该是 PayFragment)。

private void updateReceivedData() {
    Fragment frag = getSupportFragmentManager().findFragmentByTag("PayFragment");
    if (frag instanceof MyFragment) {
        frag.adjustPriceFunc();  
    }                  
}