Android标签意外行为

Question

我正在使用SDK API级别23的android应用程序工作，我的一个屏幕带有使用viewpager的标签布局。 问题是，当我单击一个选项卡时，创建的下一个选项卡就被火了！

这是选项卡片段的代码：

package com.systemonline.fanscoupon.coupon_tabs;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.systemonline.fanscoupon.Base.BaseFragment;
import com.systemonline.fanscoupon.R;

import java.lang.reflect.Field;

public class CouponTab extends BaseFragment {

public static TabLayout tabLayout;
public static ViewPager viewPager;
public static int int_items = 3;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View x = inflater.inflate(R.layout.cop_tabs_layout, null);
    tabLayout = (TabLayout) x.findViewById(R.id.tabs);
    viewPager = (ViewPager) x.findViewById(R.id.viewpager);

    viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));

    tabLayout.post(new Runnable() {
        @Override
        public void run() {
            tabLayout.setupWithViewPager(viewPager);
        }
    });

    return x;
}

@Override
public void onDetach() {
    super.onDetach();

    try {
        Field childFragmentManager =  Fragment.class.getDeclaredField("mChildFragmentManager");
        childFragmentManager.setAccessible(true);
        childFragmentManager.set(this, null);

    } catch (NoSuchFieldException e) {
        throw new RuntimeException(e);
    } catch (IllegalAccessException e) {
        throw new RuntimeException(e);
    }
}
 class MyAdapter extends FragmentPagerAdapter {

    public MyAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new AllCouponsFragment();
            case 1:
                return new OnlyForYouCouponsFragment();
            case 2:
                return new MyCouponsFragment();
        }
        return null;
    }


    @Override
    public int getCount() {

        return int_items;

    }

    @Override
    public CharSequence getPageTitle(int position) {

        switch (position) {
            case 0:
                return getResources().getString(R.string.all_cop);
            case 1:
                return getResources().getString(R.string.only_for_you);
            case 2:
                return getResources().getString(R.string.my_cop);
        }
        return null;
    }
}
}

这是布局XML的代码：

<android.support.design.widget.TabLayout
    android:id="@+id/tabs"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/material_blue_grey_800"
    app:tabGravity="fill"
    app:tabIndicatorColor="@color/orange"
    app:tabMode="fixed"
    app:tabSelectedTextColor="@color/orange"
    app:tabTextColor="@color/white">

</android.support.design.widget.TabLayout>

<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

</android.support.v4.view.ViewPager>

Answer 1

我不认为这是意外的行为。 因为ViewPager默认加载3个项目。

1. 以前
2. 当前
3. 下一个

因此，当您移动任何项目时，它将自动创建下一个项目并调用onCreate() 。