Question

我的应用程序中有一些选项卡，但每个选项卡都有一些大的网络调用，所以在启动我的应用程序时加载它们是不切实际的。我如何实现一些事情来逐个加载片段，所以当用户切换到另一个选项卡时，它将加载该等。

我尝试使用setoffscreenpagelimit（1），但它无法正常工作。

Answer 1

以下是将碎片添加到View寻呼机的完整代码。由于这只是一个演示，我只使用了一个textView，并且每个添加的片段都会有一个随机颜色。点击一个按钮就可以添加任意数量的片段。点击页面，你可以将它从View Pager中删除。您可以通过向右或向左滑动在View Pager中从一个页面移动到另一个页面。

MainActivity.java

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.widget.Button;
import java.util.ArrayList;
import java.util.Random;

public class MainActivity extends FragmentActivity {

    private MyPagerAdapter mpg;
    private ArrayList<MyFragment> fragmentlist = new ArrayList<>();
    public FragmentManager fmr    = getSupportFragmentManager();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final ViewPager pager  = (ViewPager) findViewById(R.id.viewPager);
        mpg = new MyPagerAdapter(fmr,fragmentlist);
        pager.setAdapter(mpg);

        for (int q = 0; q < 5; q++) {
            int r = new Random().nextInt(100) + 155;
            int g = new Random().nextInt(100) + 155;
            int b = new Random().nextInt(100) + 155;
            fragmentlist.add(MyFragment.newInstance(q, "Page number: " + (q + 1), Color.rgb(r, g, b)));
            mpg.notifyDataSetChanged();
        }

        Button  B1 = (Button) findViewById(R.id.button);
        B1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                int r = new Random().nextInt(100) + 155;
                int g = new Random().nextInt(100) + 155;
                int b = new Random().nextInt(100) + 155;
                int count = mpg.getCount();
                fragmentlist.add(MyFragment.newInstance(count, "Page number: " + (count+1), Color.rgb(r, g, b)));
                mpg.notifyDataSetChanged();

            }
        });
    }

    public void delete(int pos) {

        int i = 0;
        while (i <= fragmentlist.size()) {
            if (pos == fragmentlist.get(i).getPosition()) break;
            i++;

        }

        fragmentlist.remove(i);
        mpg.notifyDataSetChanged();
    }

    public class MyPagerAdapter extends FragmentStatePagerAdapter {

        private ArrayList<MyFragment> fragmentList;
        public MyPagerAdapter(FragmentManager fm, ArrayList<MyFragment> f) {
            super(fm);
            this.fragmentList = f;
        }

        @Override
        public Fragment getItem(int pos) {
            return fragmentlist.get(pos);
        }

        @Override
        public int getCount() {
            return fragmentlist.size();
        }

        @Override
        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }
    }
}

MyFragment.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.TextView;

import java.util.List;

public class MyFragment extends Fragment {

    int pos;

    @Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.f_1, container, false);
        pos = getArguments().getInt("num");
        v.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Log.v("MainActivity", "Deleting at pos - " + pos);
                MainActivity activity = (MainActivity) getActivity();
                activity.delete(pos);
            }
        });

        TextView tv = (TextView) v.findViewById(R.id.tvFragFirst);
        FrameLayout fl = (FrameLayout) v.findViewById(R.id.frame_layout);
        tv.setText(getArguments().getString("msg"));
        fl.setBackgroundColor(getArguments().getInt("colour"));
        return v;
    }

    public int getPosition() {
        return pos;
    }

    public static MyFragment newInstance(int num,String text,int clr) {

        MyFragment f = new MyFragment();
        Bundle b = new Bundle();
        b.putString("msg", text);
        b.putInt("colour", clr);
        b.putInt("num",num);
        f.setArguments(b);
        return f;
    }
}

和xml.files，

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.shakthivels.assingment10.MainActivity"
    android:id="@+id/r_v"
    >

    <android.support.v4.view.ViewPager
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/viewPager"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ADD a fragment"
        android:id="@+id/button"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

f_1.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/av"
     >

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:id="@+id/frame_layout">

        <TextView
            android:id="@+id/tvFragFirst"
            android:layout_width="203dp"
            android:layout_height="127dp"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:textSize="26sp"
            android:text="TextView"
            android:layout_gravity="center"
            android:textColor="#000000" />

    </FrameLayout>
</RelativeLayout>

Already Existing Fragment 1 Newly added Fragment to the view Pager 2

Viewpager逐个加载片段

1 个答案: