Question

在我的应用中，我正在创建使用Fragments和pageAdapter的标签。在我的TabsViewPagerFragmentActivity类中，我收到错误：

fm cannot be resolved to a variable TabsViewPagerFragmentActivity.java  /LoginAndRegistration/src/com/example/loginandregistration  line 47 Java Problem

当我按照快速修复选项时，我选择创建一个局部变量然后它告诉我初始化fm（顺便说一下fm代表FragmentManager）但是然后它将它设置为 null 我在我的PageAdapter中定义了fm：

public class MyPageAdapter extends FragmentPagerAdapter {

// Declare the number of ViewPager pages
final int PAGE_COUNT = 3;

public MyPageAdapter(FragmentManager fm) {
super(fm);
}

所以我的问题是：我应该遵循快速解决方案吗？如果是这样，我应该将 null 值更改为？或者我应该在PageAdapter课程中更改某些内容吗？这里也是TabsViewPagerFragmentActivity.java：

package com.example.loginandregistration;

import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.content.LocalBroadcastManager;
import com.example.loginandregistration.MyPageAdapter;

public class TabsViewPagerFragmentActivity extends FragmentActivity {

// Declare Variables
ActionBar mActionBar;
ViewPager mPager;
Tab tab;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Get the view from dashboard.xml
    setContentView(R.layout.dashboard);

    // Activate Navigation Mode Tabs
    mActionBar = getActionBar();
    mActionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Locate ViewPager in activity_main.xml
    mPager = (ViewPager) findViewById(R.id.pager);

    // Capture ViewPager page swipes
    ViewPager.SimpleOnPageChangeListener ViewPagerListener = new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            super.onPageSelected(position);
            // Find the ViewPager Position
            mActionBar.setSelectedNavigationItem(position);
        }
    };

    mPager.setOnPageChangeListener(ViewPagerListener);
    // Locate the adapter class called ViewPagerAdapter.java
    MyPageAdapter viewpageradapter = new MyPageAdapter(fm);
    // Set the View Pager Adapter into ViewPager
    mPager.setAdapter(viewpageradapter);

    // Capture tab button clicks
    ActionBar.TabListener tabListener = new ActionBar.TabListener() {

         @Override
         public void onTabSelected(Tab tab, FragmentTransaction ft) {
             // Pass the position on tab click to ViewPager
             mPager.setCurrentItem(tab.getPosition());
         }

         @Override
         public void onTabUnselected(Tab tab, FragmentTransaction ft) {
             // TODO Auto-generated method stub
         }

         @Override
         public void onTabReselected(Tab tab, FragmentTransaction ft) {
             // TODO Auto-generated method stub
         }
     };



    // Create first Tab
    tab = mActionBar.newTab().setText("Tab1").setTabListener(tabListener);
    mActionBar.addTab(tab);

    // Create second Tab
    tab = mActionBar.newTab().setText("Tab2").setTabListener(tabListener);
    mActionBar.addTab(tab);

    // Create third Tab
    tab = mActionBar.newTab().setText("Tab3").setTabListener(tabListener);
    mActionBar.addTab(tab);

}

}

Answer 1

提供从Activity到适配器构造函数的片段管理器：

如果您使用支持库：

MyPageAdapter viewpageradapter = new MyPageAdapter(getSupportFragmentManager());

局部变量fm无法解析为类型

1 个答案: