使用ViewPager时模拟器中没有图像显示

Question

但是，在尝试为大学创建基本的幻灯片应用程序时，我很难在自己的活动中实现ViewPager功能。

该代码正在运行，没有任何错误，但恼人的是只显示空白屏幕。 我希望它显示Drawable文件夹中的5/6图像。

任何想法来显示图像将不胜感激。

谢谢

这是我的Java文件：

package com.example.uuj.belfastphotoslider;

import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

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

public class BelfastActivity extends FragmentActivity {
    /**
     * The number of pages (wizard steps) to show in this demo.
     */
    private static final int NUM_PAGES = 5;

    /**
     * The pager widget, which handles animation and allows swiping horizontally to access previous
     * and next wizard steps.
     */
    private ViewPager mPager;

    /**
     * The pager adapter, which provides the pages to the view pager widget.
     */
    private PagerAdapter mPagerAdapter;

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

            // Instantiate a ViewPager and a PagerAdapter.
            mPager = (ViewPager) findViewById(R.id.pager);
            mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
            mPager.setAdapter(mPagerAdapter);

        int[] mResources = {
                R.drawable.ni_map,
                R.drawable.map
        };

        }

        @Override
        public void onBackPressed() {
            if (mPager.getCurrentItem() == 0) {
                // If the user is currently looking at the first step, allow the system to handle the
                // Back button. This calls finish() on this activity and pops the back stack.
                super.onBackPressed();
            } else {
                // Otherwise, select the previous step.
                mPager.setCurrentItem(mPager.getCurrentItem() - 1);
            }
        }

        /**
         * A simple pager adapter that represents 5 ScreenSlidePageFragment objects, in
         * sequence.
         */
        private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
            public ScreenSlidePagerAdapter(FragmentManager fm) {
                super(fm);
            }

            @Override
            public Fragment getItem(int position) {
                return new ScreenSlidePageFragment();
            }

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.menu_belfast, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

这是我的.xml文件：

<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="com.example.uuj.belfastphotoslider.BelfastActivity"
android:background="#020202">

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/content"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/imageView" />

</LinearLayout>

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

我是Android Studio的初学者，所以要当心错误。

预先感谢大家。

Answer 1

我在看这段代码：

        @Override
        public Fragment getItem(int position) {
            return new ScreenSlidePageFragment();
        }

而且我看不到您在哪里给片段显示了需要显示的内容。 应该有一些根据位置而变化的东西，例如片段的参数或其他东西。 如果将代码发布到ScreenSlidePageFragment将会很有帮助。