Getview参数＆QUOT; convertview＆QUOT; NOT NULL新＆QUOT;仓位＆QUOT;参数 [英] Getview parameter "convertview" not null on new "position" parameter

问题描述

我使用ArrayAdapter为我自己的类型的对象（只有一种类型）的列表，我给用户一个选项来创建更多的项目（从而为这些项目更多的意见）。在某些时候，getView发送一个新的位置索引与一个非空convertView。然后，它示出了在最后位置的第一图。在此之后，滚动时的观点得到所有混合起来。我假设这意味着我操纵方式的意见，我不应该有，但我只是不明白的地方。下面是一些code：

I'm using an ArrayAdapter for a list of my own type of objects (only one type) and I give the user an option to create more items (thus creating more views for those items). At some point, getView sent a new "position" index with a non-null "convertView". It then shows the first view in the last position. After that, when scrolling the views get all mixed up. I'm assuming this means I manipulated the views in ways I shouldn't have but I just don't see where. Here is some code:

    @Override
public View getView(int position, View convertView, ViewGroup parent) {
    View v;
    PreviewItemHolder holder = null;

    // Initialize view if convertview is null
    if (convertView == null) {
        v = newView(parent, position);
    }
    // Populate from previously saved holder
    else {
        // Use previous item if not null
        v = convertView;
    }

    // Populate if the holder is null (newly inflated view) OR
    // if current view's holder's flag is true and requires populating
    if ((holder == null) || (holder.readPopulateFlag())) {
        bindView(position, v);
    }

    return v;
}

    private View newView(ViewGroup parent, int position) {
    // Getting view somehow...
    LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View inflatedView = inflater.inflate(R.layout.preview_element_set, parent, false);
    PreviewItemHolder holder = new PreviewItemHolder();

    holder.set = (Set) mSets.get(position);
    holder.previewElementHolders = new ArrayList<PreviewElementHolder>();
    holder.expandArea = (View) inflatedView.findViewById(R.id.expandArea);
    holder.repetitionsLabel = (TextView) inflatedView.findViewById(R.id.previewRepetitionsInput);
    holder.endlessInput = (CheckBox) inflatedView.findViewById(R.id.previewSetEndlessInput);
    holder.nameLabel = (TextView) inflatedView.findViewById(R.id.previewSetNameLabel);
    holder.commentInput = (EditText) inflatedView.findViewById(R.id.previewSetCommentInput);
    holder.soundInput = (EditText) inflatedView.findViewById(R.id.previewSetSoundInput);
    holder.addElementButton = (Button) inflatedView.findViewById(R.id.previewSetAddElements);
    holder.expand = (View) inflatedView.findViewById(R.id.infoArea);
    holder.collapse = (View) inflatedView.findViewById(R.id.collapse);

    final int setsLength = holder.set.getElements().size();

    for (int i = 0; i < setsLength; i++) {
        AElement currElement = holder.set.getElements().get(i);

        // Creating new element holder according to the type
        if (currElement instanceof Rest) {
            holder.previewElementHolders.add(new PreviewRestHolder());
        }
        else if (currElement instanceof TimeExercise) {
            holder.previewElementHolders.add(new PreviewTimeExerciseHolder());
        }
        else if (currElement instanceof RepetitionExercise) {
            holder.previewElementHolders.add(new PreviewRepetitionExerciseHolder());
        }

        View currLayout = inflateElement(currElement, inflater, i, holder.previewElementHolders.get(i));

        // Add the child before the hairline, collapse image and the add
        // button
        // (3 last children of the expandArea view
        ((ViewGroup) holder.expandArea).addView(currLayout, ((ViewGroup) holder.expandArea).getChildCount() - CHILDREN_INDEX_AFTER_PHASES_LABEL);
    }

    inflatedView.setTag(holder);

    return inflatedView;
}

private void bindView(int position, View inflatedView) {
    final PreviewItemHolder holder = (PreviewItemHolder) inflatedView.getTag();
    holder.set.setId(position);
    holder.endlessInput.setChecked(holder.set.getEndless());
    holder.soundInput.setText(holder.set.getSound());
    holder.nameLabel.setText(holder.set.getName());
    holder.commentInput.setText(holder.set.getComment());

    // Make sure there is a name. If none, put default
    if (holder.nameLabel.getText().equals("")) {
        holder.nameLabel.setText(R.string.default_set_name);
    }

    // Set repetitions value according to the endless flag
    if (holder.set.getEndless()) {
        holder.repetitionsLabel.setText(R.string.infinity);
    }
    else {
        holder.repetitionsLabel.setText(String.valueOf(holder.set.getRepetitions()));
    }

    // Set click listeners
    holder.endlessInput.setOnCheckedChangeListener(new OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

            // Save endless flag
            holder.set.setEndless(isChecked);

            // If an endless set - Dropset
            if (isChecked) {
                holder.repetitionsLabel.setText(R.string.infinity);
            }
            else {
                // Regular set
                holder.repetitionsLabel.setText(String.valueOf(holder.set.getRepetitions()));
            }

            hideShowRepsWeights(holder);
        }

    });

    holder.repetitionsLabel.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {

            NumericDialog instance = NumericDialog.newInstance(holder, holder.set, NumericDialog.INTEGER_MODE, Consts.SET_REPETITIONS_METHOD_NAME);
            instance.show(((Activity) getContext()).getFragmentManager(), null);
        }
    });

    holder.nameLabel.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // Setting flag to true to allow populating this view
            holder.rePopulateFlag = true;
            SetNameDialog instance = SetNameDialog.newInstance(holder.set);
            instance.show(((Activity) getContext()).getFragmentManager(), null);
        }
    });

    holder.commentInput.setOnFocusChangeListener(new OnFocusChangeListener() {
        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if (!hasFocus) {
                // After focus is lost, save the text into the set
                holder.set.setComment(holder.commentInput.getText().toString());
            }
        }
    });

    // TODO Change that into a dialog that allows selection of sounds
    holder.soundInput.setOnFocusChangeListener(new OnFocusChangeListener() {
        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if (!hasFocus) {
                // After focus is lost, save the text into the set
                holder.set.setSound(holder.soundInput.getText().toString());
            }
        }
    });

    holder.expand.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // Change visibility - Show expandArea and its data
            holder.expandArea.setVisibility(View.VISIBLE);
            holder.expand.setVisibility(View.GONE);
            holder.collapse.setVisibility(View.VISIBLE);
        }
    });

    holder.collapse.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // Change visibility - Hide expandArea and its data
            holder.expandArea.setVisibility(View.GONE);
            holder.collapse.setVisibility(View.GONE);
            holder.expand.setVisibility(View.VISIBLE);
        }
    });

    holder.addElementButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            AddElementDialog instance = AddElementDialog.newInstance(holder);
            instance.show(((Activity) getContext()).getFragmentManager(), null);
        }
    });

    // Populate elements
    for (PreviewElementHolder elementHolder : holder.previewElementHolders) {
        populateElement(elementHolder, holder);
    }

    // Finally hide/show if needed - Should this be put somewere else?
    hideShowRepsWeights(holder);
}

请告诉我，如果你觉得我应该上传更多的方法，使事情更清晰。

Please tell me if you think I should upload more methods to make things clearer.

推荐答案

一个朋友解释这个问题对我来说，现在似乎工作。基本上ListView中仅持有少数意见，并回收他们所有的时间。在我来说，我有一个的Nexus 4，所以它似乎有7次总，因为8日总是一个谁开始作祟。我缺少在我getView（）是一个条件检查的位置和一个ArrayAdapter在当前项目的ID之间的相关性。下面是它现在看起来怎么样，它的作品：

A friend explained the problem to me and now it seems to work. Basically ListView only holds a small number of views and recycles them all the time. In my case I have a Nexus 4 and so it seems to have 7 views total because the 8th was always the one who started to cause trouble. What I was missing in my getView() was a condition checking for correlation between the position and the ID of the current item within the ArrayAdapter. Here is how it looks now that it works:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View v;
    PreviewItemHolder holder = null;

    // Initialize view if convertview is null
    if (convertView == null) {
        v = newView(parent, position);
    }
    // Populate from previously saved holder
    else {
        // If position and id of set do not match, this view needs to be re-created, not recycled
        if (((PreviewItemHolder) convertView.getTag()).set.getId() != position) {
            v = newView(parent, position);
        }
        else {
            // Use previous item if not null
            v = convertView;

            // Get holder
            holder = (PreviewItemHolder) v.getTag();
        }
    }

    // Populate if the holder is null (newly inflated view) OR
    // if current view's holder's flag is true and requires populating
     if ((holder == null) || (holder.readPopulateFlag())) {
    bindView(position, v);
     }

    return v;
}

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