重新选择选项卡时片段为空白
Fragment is blank when the tab is reselected
最初片段returns第一个和第二个选项卡对应的列表视图。但是 returns 第三个选项卡的空片段。当我 select 时,第一个选项卡再次显示空片段。列表适配器没问题
.当我在第二个选项卡中设置适配器时,它工作正常。问题出在 Mainactivity 和 Fragment
主要活动
public class SwipemainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener
{
private TextView displayTextView;
public static SwipemainActivity instance;
TabLayout tabLayout;
ViewPager viewPager;
Context context;
FragmentAdapterClass fragmentAdapter;
public static Context getInstance() {
return instance;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_swipemain);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
instance = this;
tabLayout = (TabLayout) findViewById(R.id.tabs);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setSupportActionBar(toolbar);
tabLayout.addTab(tabLayout.newTab().setText("NEW"));
tabLayout.addTab(tabLayout.newTab().setText("CONFIRMED"));
tabLayout.addTab(tabLayout.newTab().setText("FINISHED"));
fragmentAdapter = new FragmentAdapterClass(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(fragmentAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab LayoutTab) {
viewPager.setCurrentItem(LayoutTab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab LayoutTab) {
}
@Override
public void onTabReselected(TabLayout.Tab LayoutTab) {
}
});
}
}
片段
public class FragmentAdapterClass extends FragmentStatePagerAdapter {
int TabCount;
public FragmentAdapterClass(FragmentManager fragmentManager, int CountTabs) {
super(fragmentManager);
this.TabCount = CountTabs;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
Tab1 tab1 = new Tab1();
return tab1;
case 1:
Tab2 tab2 = new Tab2();
return tab2;
case 2:
Tab3 tab3 = new Tab3();
return tab3;
default:
return null;
}
}
@Override
public int getCount() {
return TabCount;
}
}
我从不使用此侦听器来更改 viewpager 片段。并使用 setOffScreenPageLimit 告诉 viewpager 需要在内存中保存多少片段。这就是我总是使用 tabbedlayout 和 viewpager 设置片段的方式。
viewPager.setOffscreenPageLimit(AMOUNT_OF_FRAGMENTS);
最初片段returns第一个和第二个选项卡对应的列表视图。但是 returns 第三个选项卡的空片段。当我 select 时,第一个选项卡再次显示空片段。列表适配器没问题 .当我在第二个选项卡中设置适配器时,它工作正常。问题出在 Mainactivity 和 Fragment
主要活动
public class SwipemainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener
{
private TextView displayTextView;
public static SwipemainActivity instance;
TabLayout tabLayout;
ViewPager viewPager;
Context context;
FragmentAdapterClass fragmentAdapter;
public static Context getInstance() {
return instance;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_swipemain);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
instance = this;
tabLayout = (TabLayout) findViewById(R.id.tabs);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setSupportActionBar(toolbar);
tabLayout.addTab(tabLayout.newTab().setText("NEW"));
tabLayout.addTab(tabLayout.newTab().setText("CONFIRMED"));
tabLayout.addTab(tabLayout.newTab().setText("FINISHED"));
fragmentAdapter = new FragmentAdapterClass(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(fragmentAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab LayoutTab) {
viewPager.setCurrentItem(LayoutTab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab LayoutTab) {
}
@Override
public void onTabReselected(TabLayout.Tab LayoutTab) {
}
});
}
}
片段
public class FragmentAdapterClass extends FragmentStatePagerAdapter {
int TabCount;
public FragmentAdapterClass(FragmentManager fragmentManager, int CountTabs) {
super(fragmentManager);
this.TabCount = CountTabs;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
Tab1 tab1 = new Tab1();
return tab1;
case 1:
Tab2 tab2 = new Tab2();
return tab2;
case 2:
Tab3 tab3 = new Tab3();
return tab3;
default:
return null;
}
}
@Override
public int getCount() {
return TabCount;
}
}
我从不使用此侦听器来更改 viewpager 片段。并使用 setOffScreenPageLimit 告诉 viewpager 需要在内存中保存多少片段。这就是我总是使用 tabbedlayout 和 viewpager 设置片段的方式。
viewPager.setOffscreenPageLimit(AMOUNT_OF_FRAGMENTS);