FragmentManager的FragmentStatePageAdapter错误（处理ViewPager）

Question

我刚刚开始学习如何编程，很抱歉，如果这是一个奇怪或愚蠢的问题。

我正在使用ViewPager制作SlideingScreen。我从这里复制了代码（http://developer.android.com/training/animation/screen-slide.html），但我不断收到错误。

以下是具有两个内容的代码：

package com.example.ryanfolz.gridgame;

import android.support.v4.app.Fragment;
import android.app.FragmentManager;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.NavUtils;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.view.WindowManager;

public class ScreenSlideActivity 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);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_screen_slide);

    // Instantiate a ViewPager and a PagerAdapter.
    mPager = (ViewPager) findViewById(R.id.pager);
    mPagerAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
    mPager.setAdapter(mPagerAdapter);
    mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {

            //invalidateOptionsMenu();
        }
    });
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);
    getMenuInflater().inflate(R.menu.activity_screen_slide, menu);

    menu.findItem(R.id.action_previous).setEnabled(mPager.getCurrentItem() > 0);

    // Add either a "next" or "finish" button to the action bar, depending on which page
    // is currently selected.
    MenuItem item = menu.add(Menu.NONE, R.id.action_next, Menu.NONE,
            (mPager.getCurrentItem() == mPagerAdapter.getCount() - 1)
                    ? R.string.action_finish
                    : R.string.action_next);
    item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM | MenuItem.SHOW_AS_ACTION_WITH_TEXT);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            // Navigate "up" the demo structure to the launchpad activity.
            // See http://developer.android.com/design/patterns/navigation.html for more.
            NavUtils.navigateUpTo(this, new Intent(this, MainActivity.class));
            return true;

        case R.id.action_previous:
            // Go to the previous step in the wizard. If there is no previous step,
            // setCurrentItem will do nothing.
            mPager.setCurrentItem(mPager.getCurrentItem() - 1);
            return true;

        case R.id.action_next:
            // Advance to the next step in the wizard. If there is no next step, setCurrentItem
            // will do nothing.
            mPager.setCurrentItem(mPager.getCurrentItem() + 1);
            return true;
    }

    return super.onOptionsItemSelected(item);
}

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

        super(fm);
    }

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

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

}

片段在这里

package com.example.ryanfolz.gridgame;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class ScreenSlidePageFragment extends Fragment {
/**
 * The argument key for the page number this fragment represents.
 */
public static final String ARG_PAGE = "page";
ViewGroup rootView;

private int mPageNumber;

/**
 * Factory method for this fragment class. Constructs a new fragment for the given page number.
 */
public static ScreenSlidePageFragment create(int pageNumber) {
    ScreenSlidePageFragment fragment = new ScreenSlidePageFragment();
    Bundle args = new Bundle();
    args.putInt(ARG_PAGE, pageNumber);
    fragment.setArguments(args);
    return fragment;
}

public ScreenSlidePageFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mPageNumber = getArguments().getInt(ARG_PAGE);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // Inflate the layout containing a title and body text.
    if(mPageNumber == 1){
        rootView = (ViewGroup) inflater
                .inflate(R.layout.test, container, false);
        ((TextView) rootView.findViewById(R.id.test)).setText("Hello");
    }else {
        rootView = (ViewGroup) inflater
                .inflate(R.layout.fragment_screen_slide_page, container, false);

        // Set the title view to show the page number.
        ((TextView) rootView.findViewById(android.R.id.text1)).setText(
                getString(R.string.title_template_step, mPageNumber + 1));
    }

    return rootView;
}

public int getPageNumber() {
    return mPageNumber;
}

}

Answer 1

从导入中删除这些行

import android.app.FragmentManager;
import android.app.Fragment;

当您的IDE要求导入哪个类时，您应该从支持包中选择这些类，如下所示：

android.support.v4.app.FragmentStatePagerAdapter;

您应该调用getSupportFragmentManager（）

而不是使用getFragmentManager（）

Answer 2

  

我正在使用ViewPager制作SlideingScreen。我从这里复制了代码（http://developer.android.com/training/animation/screen-slide.html），但我不断收到错误

如果您正确检查了示例，他们已导入

import android.support.v4.app.FragmentManager;

而不是

import android.app.FragmentManager;

他们也使用了

getSupportFragmentManager()

而不是

getFragmentManager()

此更改是必需的，因为您正在为片段使用android支持库。

Answer 3

在ScreenSlideActivity文件中，更改

import android.app.FragmentManager;

到

import android.support.v4.app.FragmentManager;

对于ScreenSlidePageFragment，请更改此行

import android.app.Fragment;

进入这个

import android.support.v4.app.Fragment;

最后。全部改变

getFragmentManager()

到

getSupportFragmentManager()