FragmentPagerAdapter麻烦和困境:构造函数未定义

Question

编辑:我已经重新编写了一些代码来尝试通过错误(但现在应用程序在启动时崩溃).首先,我的类现在扩展了FragmentActivity,以便我可以访问方法getSupportFragmentManager();. 然后,在创建中,我改变了我的构造函数:

mTabsAdapter = new TabsAdapter(this.getSupportFragmentManager(), this, mViewPager);

从那里,在我的子类中,我更改了代码以反映这一点:

public TabsAdapter(FragmentManager fm, Activity activity, ViewPager pager) {
    super(fm);
    mContext = activity;
    mActionBar = activity.getActionBar();
    mViewPager = pager;
    mViewPager.setAdapter(this);
    mViewPager.setOnPageChangeListener(this);
}

正如我所说,它仍然崩溃,此时有任何想法吗？

开始原始问题: 我有以下错误:"构造函数FragmentPagerAdapter(FragmentManager)未定义"*

当我尝试执行以下行时:

super(activity.getFragmentManager());这一行遵循我public TabsAdapter(Activity activity, ViewPager pager) {的扩展FragmentPagerAdapter.

基本上,我正在尝试获取我的8+片段应用程序(8个片段,一个活动,其中包含一组链接到每个片段的ActionBar选项卡[为简洁起见,此处仅显示一个"loginTab"]).

这是我的整个代码:

编辑:我用于参考的页面: http ://developer.android.com/reference/android/support/v4/view/ViewPager.html

http://thepseudocoder.wordpress.com/2011/10/05/android-page-swiping-using-viewpager/

package com.davekelley.polling;

import java.util.ArrayList;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;

public class Polling extends Activity {

    private ViewPager mViewPager;
    private TabsAdapter mTabsAdapter;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mViewPager = new ViewPager(this);
        mViewPager.setId(R.id.pager);
        setContentView(mViewPager);
        final ActionBar bar = getActionBar();
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        bar.setDisplayShowTitleEnabled(false);
        bar.setDisplayShowHomeEnabled(false);
        mTabsAdapter = new TabsAdapter(this, mViewPager);
        mTabsAdapter.addTab(bar.newTab().setText(“Simple”),
        LoginFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(“Simple”),
        EconFragment.class, null);
        mTabsAdapter.addTab(bar.newTab().setText(“Simple”),
        PoliticsFragment.class, null);

        if (savedInstanceState != null) {
            bar.setSelectedNavigationItem(savedInstanceState.getInt(“tab”, 0));
        }
    }
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(“tab”, getActionBar().getSelectedNavigationIndex());
    }

    public static class TabsAdapter extends FragmentPagerAdapter
    implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
        private final Context mContext;
        private final ActionBar mActionBar;
        private final ViewPager mViewPager;
        private final ArrayList mTabs = new ArrayList();

        static final class TabInfo {
            private final Class clss;
            private final Bundle args;

            TabInfo(Class _class, Bundle _args) {
                clss = _class;
                args = _args;
            }
        }

        public TabsAdapter(Activity activity, ViewPager pager) {
            super(activity.getFragmentManager());
            mContext = activity;
            mActionBar = activity.getActionBar();
            mViewPager = pager;
            mViewPager.setAdapter(this);
            mViewPager.setOnPageChangeListener(this);
        }

        public void addTab(ActionBar.Tab tab, Class clss, Bundle args) {
            TabInfo info = new TabInfo(clss, args);
            tab.setTag(info);
            tab.setTabListener(this);
            mTabs.add(info);
            mActionBar.addTab(tab);
            notifyDataSetChanged();
        }

        public int getCount() {
            return mTabs.size();
        }

        public Fragment getItem(int position) {
            TabInfo info = mTabs.get(position);
            return Fragment.instantiate(mContext, info.clss.getName(), info.args);
        }

        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        public void onPageSelected(int position) {
            mActionBar.setSelectedNavigationItem(position);
        }

        public void onPageScrollStateChanged(int state) {
        }

        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            Object tag = tab.getTag();
            for (int i=0; i<mTabs.size(); i++) {
                if (mTabs.get(i) == tag) {
                    mViewPager.setCurrentItem(i);
                }
            }
        }

        public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        }

        public void onTabReselected(Tab tab, FragmentTransaction ft) {
        }

        public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
        }

        public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
        }

        public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {
        }
    }
}

知道这里发生了什么,我能做些什么来解决它？我的Fragment类目前非常简单,但最终将从SQL服务器加载数据(与此同时,它们只返回一个简单的膨胀布局).

Answer 1

我已经解决了这个问题.需要的是无数的解决方案.

首先,我不得不扩展FragmentActivity.

public class Polling extends FragmentActivity {

然后,在创建我的TabsAdapter时,我不得不发送一个调用(FragmentActivity本身):

mTabsAdapter = new TabsAdapter(this, mViewPager);

然后,当在TabsAdapter子类中创建构造函数时,我不得不将参数更改为FragmentActivity而不是Activity:

public TabsAdapter(FragmentActivity activity, ViewPager pager) {
    super(activity.getSupportFragmentManager());

最后,我必须在Fragment类中更改我的import语句,以反映兼容性库而不是常规片段包的使用:

import android.support.v4.app.Fragment;

所以,现在我的ViewPager功能.当然,单击每个单独的选项卡图标以在选项卡之间切换不再有效(因此我在发送此消息时正在处理该解决方案).无论如何,现在ViewPager正常运行,我可以继续在我的应用程序中遇到更紧迫的问题.感谢LouisLouis让我走上了正确的道路.我最终使用CountingFragment.java来帮助我查看错误的位置,以及ActionBarSherlock代码中的FragmentTabsPager.java以确定是否需要指定FragmentActivity.

Answer 2

你需要改变线条

public TabsAdapter(Activity activity, ViewPager pager) {
    super(activity.getFragmentManager());

至

public TabsAdapter(Activity activity, ViewPager pager) {
    super(activity.getSupportFragmentManager());

这将提供android.support.v4.app.FragmentManager构造函数所需的内容android.support.v4.app.FragmentPagerAdapter.您目前正在提供android.app.FragmentManager,这是从中返回的activity.getFragmentManager().这导致类型不匹配,这是您的错误的根本原因.