7
MainActivity替換（）不與多片段正常工作
package example.antonio.activitydemo;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.support.v4.app.*;
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final FragmentManager fragmentManager = getSupportFragmentManager();
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
FirstFragment fragment = new FirstFragment();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.container, fragment);
fragmentTransaction.commit();
}
});
Button button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SecondFragment fragment = new SecondFragment();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.container, fragment);
fragmentTransaction.commit();
}
});
}
}
FirstFragment
package example.antonio.activitydemo;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.view.View;
public class FirstFragment extends Fragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInsanceState) {
return inflater.inflate(R.layout.first_fragment, container, false);
}
}
SecondFragment
package example.antonio.activitydemo;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.view.View;
public class SecondFragment extends Fragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInsanceState) {
return inflater.inflate(R.layout.second_fragment, container, false);
}
}
他們的XML文件：
main_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/container"
android:orientation="vertical">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start1"
android:id="@+id/button"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start2"
android:id="@+id/button2"/>
</LinearLayout>
first_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#000000">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="First!"
android:textColor="#ffffff"/>
</FrameLayout>
second_fragment.xml就像前面的一個，只有android:text="Second!"
這裏是奇怪的事情，當我點擊4次Start1按鈕，然後我得到4個字First!，直到這裏一切正常。以下如果我點擊Start2按鈕，我期望的是刪除4個以前的片段，並添加一個新的片段，出現Second!。這是我從文檔中理解的：
替換已添加到容器的現有片段。這與爲所有當前添加的片段調用remove（Fragment）相同的containerViewId，然後使用此處給出的相同參數添加（int，Fragment，String）基本相同。
但這裏是我所得到的：
我試圖讀取源代碼，也許我發現這裏是「問題」，我想知道你在想什麼如果是我在某個地方犯了錯誤。
這裏是片斷BackStackRecord.java，run()方法：
case OP_REPLACE: {
Fragment f = op.fragment;
int containerId = f.mContainerId;
if (mManager.mAdded != null) {
for (int i = 0; i < mManager.mAdded.size(); i++) {
Fragment old = mManager.mAdded.get(i);
if (FragmentManagerImpl.DEBUG) {
Log.v(TAG,
"OP_REPLACE: adding=" + f + " old=" + old);
}
if (old.mContainerId == containerId) {
if (old == f) {
op.fragment = f = null;
} else {
if (op.removed == null) {
op.removed = new ArrayList<Fragment>();
}
op.removed.add(old);
old.mNextAnim = op.exitAnim;
if (mAddToBackStack) {
old.mBackStackNesting += 1;
if (FragmentManagerImpl.DEBUG) {
Log.v(TAG, "Bump nesting of "
+ old + " to " + old.mBackStackNesting);
}
}
mManager.removeFragment(old, mTransition, mTransitionStyle);
}
}
}
}
，這裏是從FragmentManager.java的片段：
public void removeFragment(Fragment fragment, int transition, int transitionStyle) {
if (DEBUG) Log.v(TAG, "remove: " + fragment + " nesting=" + fragment.mBackStackNesting);
final boolean inactive = !fragment.isInBackStack();
if (!fragment.mDetached || inactive) {
if (false) {
// Would be nice to catch a bad remove here, but we need
// time to test this to make sure we aren't crashes cases
// where it is not a problem.
if (!mAdded.contains(fragment)) {
throw new IllegalStateException("Fragment not added: " + fragment);
}
}
**if (mAdded != null) {
mAdded.remove(fragment);
}**
if (fragment.mHasMenu && fragment.mMenuVisible) {
mNeedMenuInvalidate = true;
}
fragment.mAdded = false;
fragment.mRemoving = true;
moveToState(fragment, inactive ? Fragment.INITIALIZING : Fragment.CREATED,
transition, transitionStyle, false);
}
}
正如你所看到的， removeFragment方法從mAdded中刪除分部，但在run()方法中，i索引沒有被修改，它從它離開的地方重新啓動，以這種方式它可能會丟失一些元素...
我認爲這是一個錯誤，其他人發現相同的問題：https://code.google.com/p/android/issues/detail?id=83178&can=1&q=fragment%20replace&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars – zer0uno
嘗試調用getSupportFragmentManager（）;直接從每個按鈕的onclick正文，而不是最終 – Olu
已完成，同樣的問題。 – zer0uno