Question

首先我必须对不起，我的英语不太好

我必须在扩展片段中

在顶部添加标签布局和ViewPage

在ViewPageAdapter中添加三个片段以切换ViewPage

但是我目前不知道为什么我的适配器在模拟器上显示为空

我找到了一些文章，但我不知道哪一种适合我的当前情况。

麻烦大家给我答复和建议

我会谦虚地接受它，谢谢！

这是我的XML

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".HomeFragment">


<android.support.design.widget.TabLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimary"
    app:tabMode="fixed"
    app:tabGravity="fill"
    app:tabIndicatorColor="@color/colorAccent"
    android:id="@+id/tablayout_fragment_home"
    >

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

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

这是我的.java

package com.example.teng.myapplication;

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class HomeFragment extends android.support.v4.app.Fragment {

View view ;
private TabLayout tabLayout;
private ViewPager viewPager;
private ViewPagerAdapter adapter;


public HomeFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_home, container, false);
    return view ;
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    adapter = new ViewPagerAdapter(getChildFragmentManager());
    tabLayout = view.findViewById(R.id.tablayout_fragment_home);
    viewPager = view.findViewById(R.id.viewpager_fragment_home);
    adapter.AddFragment(new LatestNews(),"Page1");
    adapter.AddFragment(new PopularProduct(),"Page2");
    adapter.AddFragment(new ThemeActivity(),"Page3");
    viewPager.setAdapter(adapter);
    tabLayout.setupWithViewPager(viewPager);
}

}

Answer 1

您用错误的方法设置了TabLayout。正确的方法应该是onActivityCreated

onActivityCreated在创建与片段相关联的活动时最初被调用。

问题是您在OnActvityResult中初始化了适配器，当使用startActivityForResult()触发意图时调用该适配器。

将下面的代码替换为当前代码。

package com.example.teng.myapplication; 

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.TabLayout; 
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class HomeFragment extends android.support.v4.app.Fragment {

View view ;
private TabLayout tabLayout;
private ViewPager viewPager;
private ViewPagerAdapter adapter;


public HomeFragment() { 
    // Required empty public constructor 
} 


@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment 
    view = inflater.inflate(R.layout.fragment_home, container, false);
    return view ;
} 

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        initComponent();
    }


        // Initialise components and variables
    private void initComponent() {

    adapter = new ViewPagerAdapter(getChildFragmentManager());
    tabLayout = view.findViewById(R.id.tablayout_fragment_home);
    viewPager = view.findViewById(R.id.viewpager_fragment_home);
    adapter.AddFragment(new LatestNews(),"Page1");
    adapter.AddFragment(new PopularProduct(),"Page2");
    adapter.AddFragment(new ThemeActivity(),"Page3");
    viewPager.setAdapter(adapter);
    tabLayout.setupWithViewPager(viewPager);
    }


}

用以下代码替换您的XML文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
tools:context=".HomeFragment">

<android.support.design.widget.TabLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimary"
    app:tabMode="fixed"
    app:tabGravity="fill"
    app:tabIndicatorColor="@color/colorAccent"
    android:id="@+id/tablayout_fragment_home"/>


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

</LinearLayout>

由于 FrameLayout ， FrameLayout 将控件彼此置于 top 位置，因此您的点击不起作用。因此将其更改为 LinearLayout 。

ViewPagerAdapter无法在片段

1 个答案: