我在活动中有一个活动，PagerAdapter（返回一个片段）和ViewPager。
其他建议使用以下代码
//JournalEntryVC.swift
import UIKit
import Alamofire
import BXProgressHUD
import SwiftyJSON
import RealmSwift
class JournalEntryVC: UIViewController, UITableViewDelegate, UITableViewDataSource {
func reloadInitialData ( ) {
//mutable arrays containing journal entry attributes
desc.removeAllObjects()
type.removeAllObjects()
category.removeAllObjects()
metric_stat.removeAllObjects()
entryImages.removeAllObjects()
dateCreate.removeAllObjects()
comments.removeAllObjects()
entryType.removeAllObjects()
id.removeAllObjects()
//comments.removeAllObjects()
content.removeAllObjects()
patName.removeAllObjects()
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
let request = Alamofire.request(.GET, "https://gethealthie.com/entries.json", headers: [
"access-token": userCreds.objectForKey("access-token")! as! String,
"client": userCreds.objectForKey("client")! as! String,
"token-type": userCreds.objectForKey("token-type")! as! String,
"uid": userCreds.objectForKey("uid")! as! String,
"expiry": userCreds.objectForKey("expiry")! as! String
]).responseJSON { response in
print(response.response)
let json = JSON(data: response.data!)
if json.count == 0 {
BXProgressHUD.hideHUDForView(self.view);
}else {
//Realm- create object instances of Patient and Journal class
let newPatient = Patient()
let myJournal = Journal()
for i in 0 ..< json.count {
let entry = json[i]
print(entry)
let name = entry["entry_comments"]
let k = name["id"]
//add entry attributes to mutable arrays
self.type.addObject(entry["type"].stringValue)
self.desc.addObject(entry["description"].stringValue)
self.category.addObject(entry["category"].stringValue)
self.metric_stat.addObject(entry["metric_stat"].stringValue)
self.dateCreate.addObject(entry["created_at"].stringValue)
self.comments.addObject(entry["entry_comments"].rawValue)
self.entryType.addObject(entry["category"].stringValue)
let posterInfo = entry["poster"]
let first = posterInfo["first_name"].stringValue
let last = posterInfo["last_name"].stringValue
let full = first + " " + last
self.patName.addObject(full)
self.id.addObject(entry["id"].stringValue)
self.entryImages.addObject(entry["image_url"].stringValue)
//Realm- access properties in Journal class and set it equal to the current journal entry attribute i.e. json[i]
myJournal.entryType = entry["type"].stringValue
myJournal.entryCaption = entry["description"].stringValue
myJournal.entryCategory = entry["category"].stringValue
myJournal.metricStat = entry["metric_stat"].stringValue
myJournal.entryDate = entry["created_at"].stringValue
// myJournal.entryComment = entry["entry_comments"].rawValue as! String
//append a NEW journal entry to the array of journal entries in Patient class i.e. let journalEntries = List<Journal>() as the json loops thru different journal entries
newPatient.journalEntries.append(myJournal)
if i == json.count - 1 {
// do some task
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
BXProgressHUD.hideHUDForView(self.view)
}
}
}
//Realm- add newPatient object instance to realm
try! self.realm.write {
self.realm.add(newPatient)
}
}
}
}
}
}但是，我无法找到片段ExampleFragment fragment = (ExampleFragment)getFragmentManager().findFragmentById(R.id.example_fragment);
fragment.specific_function_name();
的参考资料。
这是我的活动
R.id.example_fragment布局
public class TestActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("Test1"));
tabLayout.addTab(tabLayout.newTab().setText("Test2"));
tabLayout.addTab(tabLayout.newTab().setText("Test3"));
tabLayout.addTab(tabLayout.newTab().setText("Test4"));
tabLayout.addTab(tabLayout.newTab().setText("Test5"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
viewPager = (ViewPager) findViewById(R.id.pager);
adapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
tabLayout.setScrollPosition(pageIndex,0f,true);
viewPager.setCurrentItem(pageIndex);
}
}
PageAdapter的代码
<include
android:id="@+id/toolbar"
layout="@layout/toolbar" />
<android.support.v4.widget.DrawerLayout
android:layout_below="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/main_layout" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.design.widget.TabLayout
android:id="@+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/actionBarSize"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:tabTextAppearance="@style/menuTheme"
app:tabIndicatorHeight="4dp"
app:tabMode="scrollable"
/>
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
/>
</LinearLayout>
<fragment
android:id="@+id/fragment_navigation_drawer"
android:name="com.musicplayer.mp3player.activities.FragmentDrawer"
android:layout_width="@dimen/nav_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
app:layout="@layout/fragment_navigation_drawer"
tools:layout="@layout/fragment_navigation_drawer" />
</android.support.v4.widget.DrawerLayout>
</RelativeLayout>
答案 0 :(得分：0)
尝试如下：
// Returns the fragment to display for that page
@Override
public Fragment getItem(int position) {
switch (position) {
case 0: // Fragment # 0 - This will show FirstFragment
return TestFragment.newInstance(0, "Page # 1");
case 1: // Fragment # 0 - This will show FirstFragment different title
return TestFragment2.newInstance(1, "Page # 2");
case 2: // Fragment # 1 - This will show SecondFragment
return TestFragment3.newInstance(2, "Page # 3");
default:
return null;
}
}
你可以像下面这样获取片段实例：
viewpager.getcurrentItem().yourmethod();
在Fragment Class Make Method中，如下所示：
public static DemoFragment newInstance() {
return new DemoFragment();
}
答案 1 :(得分：0)
确保片段仅初始化一次：
public class PagerAdapter extends FragmentPagerAdapter {
int mNumOfTabs;
TestFragment testFragment, testFragment2, testFragment3, testFragment4, testFragment5;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
if( testFragment == null ) testFragment = new TestFragment();
return testFragment;
case 1:
if( testFragment2 == null ) testFragment2 = new TestFragment2();
return testFragment2;
case 2:
if( testFragment3 == null ) testFragment3 = new TestFragment3();
return testFragment3;
case 3:
if( testFragment4 == null ) testFragment4 = new TestFragment4();
return testFragment4;
case 4:
if( testFragment5 == null ) testFragment5 = new TestFragment5();
return testFragment5;
default:
return null;
}
}
@Override
public int getCount() {
return mNumOfTabs;
}
}
然后调用片段上的方法：
TestFragment testFragment = (TestFragment) viewpager.getcurrentItem();
// in case you are not sure, check using instanceOf to determine the Fragment type
testFragment.specific_function_name();