Question

当我运行我的应用程序时，我得到一个空白屏幕。我有2个片段及其xml文件。

以下是我的全部代码：

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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="autogenie.designtrial.MainActivity">

    <android.support.v4.view.ViewPager
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:id="@+id/view"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_below="@+id/list" />

</RelativeLayout>

Mainactivity.java

package autogenie.designtrial;

import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

public class MainActivity extends FragmentActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ViewPager v=(ViewPager)findViewById(R.id.view);
        List<Fragment> fragments=new ArrayList<>();
        fragments.add(Fragment.instantiate(this, frag1.class.getName()));
        fragments.add(Fragment.instantiate(this, frag2.class.getName()));

        fragpageadapter fragpageadapter0=new fragpageadapter(getSupportFragmentManager(),fragments);
        v.setAdapter(fragpageadapter0);
    }

}

frag1.java

package autogenie.designtrial;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by sadhana on 25/1/16.
 */
public class frag1 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate and locate the main ImageView
        final View v1 = inflater.inflate(R.layout.frag1, container, false);
        //...
        return v1;
    }

}

frag1.xml

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

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New RadioButton"
        android:id="@+id/radioButton2"
        android:layout_gravity="center" />
</LinearLayout>

frag2.java

package autogenie.designtrial;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by sadhana on 25/1/16.
 */
public class frag2 extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate and locate the main ImageView
        final View v3 = inflater.inflate(R.layout.frag2, container, false);
        //...
        return v3;
    }
}

frag2.xml

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

    <SeekBar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/seekBar" />
</LinearLayout>

fragpageadapter.java

package autogenie.designtrial;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import java.util.ArrayList;
import java.util.List;

public class fragpageadapter extends FragmentPagerAdapter {

    List<Fragment> f;

    public fragpageadapter(FragmentManager fm,List<Fragment> f) {
        super(fm);
        this.f=f;
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment =null;
        switch (position) {
            case 0:
                fragment = f.get(position);
                break;
            case 1:
                fragment = f.get(position);
                break;}
        return fragment;
    }

    @Override
    public int getCount() {
        return 0;
    }
}

Answer 1

您在getCount()

的fragpageadapter中返回0

@Override
public int getCount() {
    return 0;
}

将其更改为f.size()，即list.size

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

Answer 2

验证您的方法getCount()。它需要返回碎片的数量。

例如：

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

为什么我的＆＃34; viewpager＆＃34;不工作？

2 个答案: