我目前开发了一个带有片段和 viewPager 的小型示例应用程序。viewPager 显示 3 个页面。在每个页面中,我都实例化了一个相同类型的片段。该片段包含一个 textView 和一个按钮。单击按钮时,我想用另一个片段替换当前片段。现在我的问题是,无论我按下哪个按钮,只有第 1 页的片段被替换。我不知道我必须在我的 pageAdapter 类中做什么,但我想这与使用相同的片段和布局有关。我想我必须确保我的 pageAdapter 更新了正确的页面,但我该如何实现呢?
为了更好地理解我为什么要实现这一点,我在菜单类型的 3 个节点中收到一个 json 字符串,并且我想将它们中的每一个用作我的 viewPager 中的一个页面。
有人可以给我看一个关于这种行为的简短而简单的例子吗?我认为这是一种基本的方法,所以它不会那么困难。
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这是代码:
public class FragmentPagerSupport extends FragmentActivity {
static final int NUM_ITEMS = 4;
MyAdapter mAdapter;
ViewPager mPager;
@Override
public void onBackPressed() {
FragmentManager fm = getFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
} else {
super.onBackPressed();
}
}
public MyAdapter getmAdapter() {
return mAdapter;
}
public ViewPager getmPager() {
return mPager;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_pager);
mAdapter = new MyAdapter(getFragmentManager(), this);
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setOffscreenPageLimit(NUM_ITEMS + 2);
mPager.setAdapter(mAdapter);
Button button = (Button) findViewById(R.id.goto_first);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mPager.setCurrentItem(0);
}
});
button = (Button) findViewById(R.id.goto_last);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mPager.setCurrentItem(NUM_ITEMS - 1);
}
});
}
}
我的适配器:
public MyAdapter(FragmentManager fm, FragmentPagerSupport fragmentPagerSupport) {
super(fm);
this.fragmentPagerSupport = fragmentPagerSupport;
}
@Override
public int getCount() {
return NUM_ITEMS;
}
@Override
public Fragment getItem(int position) {
Fragment newInstance = null;
switch (position) {
case 0:
newInstance = frag1.newInstance(position);
break;
case 1:
newInstance = frag1.newInstance(position);
break;
case 2:
newInstance = frag2.newInstance(position);
break;
case 3:
newInstance = frag2.newInstance(position);
break;
}
return newInstance;
}
Frag1 & Frag2 & ListItemFrag:
public static class frag1 extends ListFragment {
int mNum;
static frag1 newInstance(int num) {
frag1 f = new frag1();
Supply num input as an argument.
Bundle args = new Bundle();
args.putInt("num", num);
f.setArguments(args);
return f;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mNum = getArguments() != null ? getArguments().getInt("num") : 1;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_pager_list, container, false);
v.setId(mNum);
View tv = v.findViewById(R.id.text);
((TextView) tv).setText("Fragment #" + mNum);
return v;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String[] cheeses = { "Edamer", "Gauda", "Cheddar", "Mozarella", "Maasdamer" };
setListAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, cheeses));
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
Log.i("FragmentList", "Item clicked: " + id);
String itemName = (String) l.getItemAtPosition(position);
Fragment listItemFragment = ListItemFragment.newInstance(itemName);
FragmentTransaction trans = getActivity().getFragmentManager().beginTransaction();
trans.replace(R.id.root, listItemFragment, listItemFragment.getClass().getName() + "_" + mNum);
trans.addToBackStack(itemName);
trans.commit();
}
}
public static class frag2 extends ListFragment {
int mNum;
static frag2 newInstance(int num) {
frag2 f = new frag2();
Bundle args = new Bundle();
args.putInt("num", num);
f.setArguments(args);
return f;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mNum = getArguments() != null ? getArguments().getInt("num") : 1;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_pager_list, container, false);
v.setId(mNum);
View tv = v.findViewById(R.id.text);
((TextView) tv).setText("Fragment #" + mNum);
return v;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String[] cheeses = { "Edamer", "Gauda", "Cheddar", "Mozarella", "Maasdamer" };
setListAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, cheeses));
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
Log.i("FragmentList", "Item clicked: " + id);
String itemName = (String) l.getItemAtPosition(position);
Fragment listItemFragment = ListItemFragment.newInstance(itemName);
FragmentTransaction trans = getActivity().getFragmentManager().beginTransaction();
trans.replace(R.id.root, listItemFragment, listItemFragment.getClass().getName() + "_" + mNum);
trans.addToBackStack(itemName);
trans.commit();
}
}
public static class ListItemFragment extends Fragment {
String itemName;
static ListItemFragment newInstance(String itemName) {
ListItemFragment i = new ListItemFragment();
Bundle args = new Bundle();
args.putString("text", itemName);
i.setArguments(args);
return i;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
itemName = getArguments() != null ? getArguments().getString("text") : "NULL";
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_item, container, false);
View tv = v.findViewById(R.id.textView1);
((TextView) tv).setText("Cheese: " + itemName + " selected!");
return v;
}
}
寻呼机布局:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:padding="4dip"
android:gravity="center_horizontal"
android:layout_width="match_parent" android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1">
</android.support.v4.view.ViewPager>
<LinearLayout android:orientation="horizontal"
android:gravity="center" android:measureWithLargestChild="true"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:layout_weight="0">
<Button
android:id="@+id/goto_first"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="first" />
<Button android:id="@+id/goto_last"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="last">
</Button>
</LinearLayout>
Frag1 布局:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#99EE11"
android:id="@+id/test">
<TextView android:id="@+id/text"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:gravity="center_vertical|center_horizontal"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="@string/hello_world"/>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:id="@+id/root" >
<ListView android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:drawSelectorOnTop="false"/>
</FrameLayout>
Frag2 布局:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#99EE11"
android:id="@+id/test2">
<TextView android:id="@+id/text"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:gravity="center_vertical|center_horizontal"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="@string/hello_world"/>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:id="@+id/root2" >
<ListView android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:drawSelectorOnTop="false"/>
</FrameLayout>
ListItemFrag 布局:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ll"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="230dp"
android:background="#AA33EE"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>