Android：当我启动一项新活动时,Listview会自行复制,然后按回去返回它

概述我有两个列表视图,它们是视图分页器选项卡中的片段.单击列表视图中的项目时,它将启动一个新活动.但是,当我按下后退按钮返回选项卡列表视图时,列表视图加倍,如果我打开活动并再次返回,它会再次翻倍,它会继续这样做.此外,我还有另一个带有五个选项卡的选项卡列表视图,当我从其中一个视图中选择两个选项卡时.当我回到它们时,该视图中的项目会加倍,这对于所有其他选项卡都是相同的.两个listviews的代码完全相 我有两个列表视图,它们是视图分页器选项卡中的片段.单击列表视图中的项目时,它将启动一个新活动.但是,当我按下后退按钮返回选项卡列表视图时,列表视图加倍,如果我打开活动并再次返回,它会再次翻倍,它会继续这样做.此外,我还有另一个带有五个选项卡的选项卡列表视图,当我从其中一个视图中选择两个选项卡时.当我回到它们时,该视图中的项目会加倍,这对于所有其他选项卡都是相同的.两个ListvIEws的代码完全相同.我已经尝试过List.clear(),它只是清除了所有列表项,并且在视图持有者中使用了“else”语句(由其他堆栈溢出答案推荐).但每次列表视图仍然重复.除非你没有注意到,否则我对 android很新.

这是列表视图片段(Due_Today_Fragment)的代码,它位于双标签活动中.

import java.util.ArrayList;import java.util.List;import androID.content.Intent;import androID.os.Bundle;import androID.support.v4.app.Fragment;import androID.vIEw.LayoutInflater;import androID.vIEw.VIEw;import androID.vIEw.VIEwGroup;import androID.Widget.AdapterVIEw;import androID.Widget.ArrayAdapter;import androID.Widget.ImageVIEw;import androID.Widget.ListVIEw;import androID.Widget.TextVIEw;public class Due_Today_Fragment extends Fragment  {    private List<homeworkdue> myhomeworkdue;    static class VIEwHolder {        public ImageVIEw imageVIEw;        public TextVIEw HomeworkDueText;        public TextVIEw DescriptionText;        public TextVIEw TeacherText;      }    public static final String KEY_HOMEWORK="homework";    public static final String KEY_DESC="desc";    public VIEw onCreateVIEw(LayoutInflater inflater,VIEwGroup container,Bundle savedInstanceState){        return inflater.inflate(R.layout.activity_main,container,false); }    @OverrIDe    public voID onResume() {        // Todo auto-generated method stub        super.onResume();        myhomeworkdue = new ArrayList<homeworkdue>();        populatehomeworkdueList();        populateListVIEw();        registerClickCallback();    }    private voID registerClickCallback() {        ListVIEw List = (ListVIEw)getVIEw().findVIEwByID(R.ID.ListVIEw1);        List.setonItemClickListener(new AdapterVIEw.OnItemClickListener() {            public voID onItemClick(AdapterVIEw<?> parent,VIEw vIEwClicked,int position,long ID) {                homeworkdue clickedhomeworkdue = myhomeworkdue.get(position);                Intent intent = new Intent(getActivity(),homeworkdueDetailsActivity.class);                intent.putExtra(KEY_HOMEWORK,clickedhomeworkdue.getHomeworkdue());                intent.putExtra(KEY_DESC,clickedhomeworkdue.getDesciption());                startActivity(intent);            }        });        }    private voID populatehomeworkdueList() {        myhomeworkdue.add(new homeworkdue("History Homework","Description 1",R.drawable.global_studIEs,"Anderson"));        myhomeworkdue.add(new homeworkdue("Math Homework","Description 2",R.drawable.mathematics,"Klein"));        myhomeworkdue.add(new homeworkdue("English Homework","Description 3",R.drawable.english,"Reed"));        myhomeworkdue.add(new homeworkdue("Spanish Homework","Description 4",R.drawable.spanish,"Joya"));        myhomeworkdue.add(new homeworkdue("ScIEnce Homework","Description 5",R.drawable.scIEnce,"Poole"));    }    private voID populateListVIEw() {        ArrayAdapter<homeworkdue> adapter = new Mylistadapter();        ListVIEw List = (ListVIEw)getVIEw().findVIEwByID(R.ID.ListVIEw1);        List.setAdapter(adapter);    }    public class Mylistadapter extends ArrayAdapter<homeworkdue>  {        public Mylistadapter() {            super(getActivity(),R.layout.item_vIEw,myhomeworkdue);        }        @OverrIDe        public VIEw getVIEw(int position,VIEw convertVIEw,VIEwGroup parent) {            VIEwHolder holder;            if(convertVIEw==null){            convertVIEw = getActivity().getLayoutInflater().inflate(R.layout.item_vIEw,parent,false);             holder = new VIEwHolder();             holder.imageVIEw = (ImageVIEw)convertVIEw.findVIEwByID(R.ID.item_iconclass);            holder.HomeworkDueText = (TextVIEw) convertVIEw.findVIEwByID(R.ID.item_texthomeworkdue);            holder.DescriptionText = (TextVIEw) convertVIEw.findVIEwByID(R.ID.item_textdescription);            holder.TeacherText = (TextVIEw) convertVIEw.findVIEwByID(R.ID.item_textteacher);            convertVIEw.setTag(holder);            }        else {            holder = (VIEwHolder) convertVIEw.getTag();        }        homeworkdue currenthomeworkdue = myhomeworkdue.get(position);        holder.imageVIEw.setimageResource(currenthomeworkdue.getIconID());        holder.HomeworkDueText.setText(currenthomeworkdue.getHomeworkdue());        holder.DescriptionText.setText(currenthomeworkdue.getDesciption());        holder.TeacherText.setText(currenthomeworkdue.getTeacher());        return convertVIEw;    }        }}

以下是单击列表视图项时启动的活动的代码

import androID.app.Activity;import androID.content.Intent;import androID.os.Bundle;import androID.vIEw.Menu;import androID.Widget.TextVIEw;import static com.bernard.beaconportal.Due_Today_Fragment.KEY_HOMEWORK;import static com.bernard.beaconportal.Due_Today_Fragment.KEY_DESC;public class homeworkdueDetailsActivity extends Activity {    @OverrIDe    protected voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentVIEw(R.layout.activity_details);        String homework = "";        String desc = "";        Intent intent = getIntent();        if (null != intent) {            homework = intent.getStringExtra(KEY_HOMEWORK);            desc = intent.getStringExtra(KEY_DESC);        }        TextVIEw headlineTxt = (TextVIEw) findVIEwByID(R.ID.texthomeworkdue);        headlineTxt.setText(homework);        TextVIEw pubdateTxt = (TextVIEw) findVIEwByID(R.ID.textdescription);        pubdateTxt.setText(desc);    }}

这是tabs片段的代码

import java.lang.reflect.FIEld;import com.actionbarsherlock.app.SherlockFragment;import com.astuetz.PagerSlIDingTabStrip;import androID.os.Bundle;import androID.support.v4.app.Fragment;import androID.support.v4.vIEw.VIEwPager;import androID.vIEw.LayoutInflater;import androID.vIEw.VIEw;import androID.vIEw.VIEwGroup;public class Fragments2 extends SherlockFragment {    @OverrIDe    public VIEw onCreateVIEw(LayoutInflater inflater,Bundle savedInstanceState) {        VIEw vIEw = inflater.inflate(R.layout.vIEwpager_main,false);        // Locate the VIEwPager in vIEwpager_main.xml        VIEwPager pager = (VIEwPager) vIEw.findVIEwByID(R.ID.vIEwPager);        // Set the VIEwPagerAdapter into VIEwPager        pager.setAdapter(new VIEwPagerAdapter(getChildFragmentManager()));        PagerSlIDingTabStrip tabs = (PagerSlIDingTabStrip) vIEw.findVIEwByID(R.ID.pagerTabStrip);        tabs.setVIEwPager(pager);        return vIEw;    }    @OverrIDe    public voID onDetach() {        super.onDetach();        try {            FIEld childFragmentManager = Fragment.class                    .getDeclaredFIEld("mChildFragmentManager");            childFragmentManager.setAccessible(true);            childFragmentManager.set(this,null);        } catch (NoSuchFIEldException e) {            throw new RuntimeException(e);        } catch (illegalaccessexception e) {            throw new RuntimeException(e);        }    }}

这里是为家庭作业定义字符串的地方

public class homeworkdue {    private String homework;    private String desc;    private int IconID;    private String teacher;    public homeworkdue(String homework,String desc,int IconID,String teacher) {        super();        this.homework = homework;        this.desc = desc;        this.IconID = IconID;        this.teacher = teacher;    }    public String getHomeworkdue() {        return homework;    }    public String getDesciption() {        return desc;    }       public int getIconID() {        return IconID;    }       public String getTeacher() {        return teacher;    }    }

这是片段的代码,它包含在五个选项卡中

import java.util.ArrayList;import java.util.List;import androID.os.Bundle;import androID.support.v4.app.Fragment;import androID.vIEw.LayoutInflater;import androID.vIEw.VIEw;import androID.vIEw.VIEwGroup;import androID.Widget.ArrayAdapter;import androID.Widget.ListVIEw;import androID.Widget.TextVIEw;public class Thursday extends Fragment  {    public VIEw onCreateVIEw(LayoutInflater inflater,Bundle savedInstanceState){        return inflater.inflate(R.layout.schedule_List_vIEw,false); }    private List<schedule> myschedule = new ArrayList<schedule>();    static class VIEwHolder {        public TextVIEw HomeworkDueText;      }    public voID onStart() {        super.onStart();        populatescheduleList();        populateListVIEw();    }    private voID populatescheduleList() {        myschedule.add(new schedule("E Band"));        myschedule.add(new schedule("G Band"));        myschedule.add(new schedule("F Band"));        myschedule.add(new schedule("H Band"));        myschedule.add(new schedule("A Band"));        myschedule.add(new schedule("C Band"));        myschedule.add(new schedule("D Band"));    }    private voID populateListVIEw() {        ArrayAdapter<schedule> adapter = new Mylistadapter();        ListVIEw List = (ListVIEw)getVIEw().findVIEwByID(R.ID.ListVIEw2);        List.setAdapter(adapter);    }     public class Mylistadapter extends ArrayAdapter<schedule>  {            public Mylistadapter() {                super(getActivity(),myschedule);            }            @OverrIDe            public VIEw getVIEw(int position,VIEwGroup parent) {                VIEwHolder holder;                if(convertVIEw==null){                    convertVIEw = getActivity().getLayoutInflater().inflate(R.layout.schedule_List_item,false);                 holder = new VIEwHolder();                 holder.HomeworkDueText = (TextVIEw) convertVIEw.findVIEwByID(R.ID.bandText);                convertVIEw.setTag(holder);                }            else {                holder = (VIEwHolder) convertVIEw.getTag();            }                schedule currenthomeworkdue = myschedule.get(position);                holder.HomeworkDueText.setText(currenthomeworkdue.Band());            return convertVIEw;        }        }}

这里是为计划定义字符串的地方

public class schedule {    private String band;    public schedule(String band) {        super();        this.band = band;    }    public String Band() {        return band;    }}

如果您需要更多信息,请提前询问并感谢您的帮助

我一直试图修复这个错误两天,我的智慧结束了.

解决方法 我们在创建片段时一次声明一个新List的原因,所以当你回到你的片段时它不会声明一个新片段,而是使用旧片段.所以为了解决这个问题,你需要将以下代码分成两部分：

private List<homeworkdue> myhomeworkdue = new ArrayList<homeworkdue>();

部分在你的片段中进入onResume,你还需要删除onStart和onStart中的所有内容到onResume.但首先保持这样的声明：

private List<homeworkdue> myhomeworkdue;

并将其余部分移至onResume.

@OverrIDeprotected voID onResume() {    // Todo auto-generated method stub    super.onResume();    myhomeworkdue = new ArrayList<homeworkdue>();    populatehomeworkdueList();    populateListVIEw();    registerClickCallback();}

您的第二个ListVIEw中的相同问题,因为它们是相同的.

希望这对你有用.如果有效,请给我一个反馈.

总结

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