我是Android和Java编程的新手,最近遇到了一个问题.我一直在寻找答案几个小时,但没有成功.
我有一个自定义ListView和一个自定义适配器,其中一行包含一个CheckBox和一个EditText.每当它第一次显示时,都可以,但是当我向下滚动时,它开始更改CheckBox和EditText的值.
这是我的row_edit.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<EditText
android:id="@+id/bonus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:inputType="numberSigned"
android:gravity="right"
android:selectAllOnFocus="true"
android:textSize="16sp" />
<CheckBox
android:id="@+id/checkBox_person"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_toLeftOf="@id/bonus"
android:textSize="16sp" />
</RelativeLayout>
Item_edit(适配器的项目)：
public class Item_edit {
private String meno;
private boolean ucast;
private int bonus;
public Item_edit(String meno, boolean ucast, int bonus) {
super();
this.meno = meno;
this.ucast = ucast;
this.bonus = bonus;
}
public String getMeno() {
return meno;
}
public boolean getUcast() {
return ucast;
}
public int getBonus() {
return bonus;
}
public void setMeno(String meno) {
this.meno = meno;
}
public void setUcast(boolean ucast) {
this.ucast = ucast;
}
public void setBonus(int bonus) {
this.bonus = bonus;
}
}
当我滚动时,ListView并不流畅,这就是为什么我决定使用ViewHolder的原因.
Adapter_edit：
public class Adapter_edit extends ArrayAdapter<Item_edit> {
private final Context context;
private final ArrayList<Item_edit> itemsArrayList;
private final Edit edit;
public Adapter_edit(Context context, ArrayList<Item_edit> itemsArrayList, Edit edit) {
super(context, R.layout.row_edit, itemsArrayList);
this.edit = edit;
this.context = context;
this.itemsArrayList = itemsArrayList;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.row_edit, parent, false);
holder = new ViewHolder();
//Log.e("NewHolder", "position = " + position);
holder.checkBox = (CheckBox) convertView
.findViewById(R.id.checkBox_person);
holder.bonus = (EditText) convertView.findViewById(R.id.bonus);
convertView.setTag(holder);
holder.checkBox.setText(itemsArrayList.get(position).getMeno());
holder.checkBox.setChecked(itemsArrayList.get(position).getUcast());
holder.bonus.setText(Integer.toString(itemsArrayList.get(position)
.getBonus()));
holder.checkBox
.setonCheckedchangelistener(new OnCheckedchangelistener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
itemsArrayList.get(position).setUcast(isChecked);
}
});
holder.bonus.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
try {
if (itemsArrayList.get(position).getBonus() != Integer
.parseInt(s.toString()) && !edit
.getUcast(position)) {
itemsArrayList.get(position).setBonus(
Integer.parseInt(s.toString()));
itemsArrayList.get(position).setUcast(true);
}
}
catch (NumberFormatException e) {
itemsArrayList.get(position).setBonus(0);
}
}
@Override
public void afterTextChanged(Editable s) {
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
});
}
else {
holder = (ViewHolder) convertView.getTag();
}
holder.checkBox.setText(itemsArrayList.get(position).getMeno());
holder.checkBox.setChecked(itemsArrayList.get(position).getUcast());
holder.bonus.setText(Integer.toString(itemsArrayList.get(position)
.getBonus()));
return convertView;
}
static class ViewHolder {
CheckBox checkBox;
EditText bonus;
}
}
使用LogCat调试后,我知道仅生成了8个持有人(因为有(0-7)个适合我的屏幕的项目).当我向下滚动时,这些已被重用.没有为位置大于7的项目创建OnCheckedchangelisteners和TextChangedListeners.
我不知道该怎么做.有人能帮我吗？
解决方法:
我终于得到了答案.
我扩展了EditText,使之成为我自己的类UpgEditText,该类可以使用setonTextChangedListener方法,这意味着删除现有的TextWatcher并添加一个新的类.
UpgEditText
public class UpgEditText extends EditText {
public UpgEditText(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public UpgEditText(Context context, AttributeSet attrs) {
super(context, attrs);
}
public UpgEditText(Context context) {
super(context);
}
TextWatcher watcher = null;
public void setonTextChangedListener(final int position, final Adapter_edit adapter) {
if (watcher != null) {
this.removeTextChangedListener(watcher);
}
watcher = new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void afterTextChanged(Editable s) {
try {
adapter.itemsArrayList.get(position).setBonus(
Integer.parseInt(s.toString()));
}
catch (Exception e) {
}
}
};
this.addTextChangedListener(watcher);
}
}
我也通常使用ViewHolder：
public class ViewHolder {
CheckBox chBoxUcast;
UpgEditText edTBonus;
}
CustomAdapter getView()方法：
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.row_edit, parent, false);
holder = new ViewHolder();
holder.chBoxUcast = (CheckBox) convertView
.findViewById(R.id.checkBox_person);
holder.edTBonus = (UpgEditText) convertView
.findViewById(R.id.bonus);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
holder.edTBonus.setonTextChangedListener(position, this);
holder.chBoxUcast
.setonCheckedchangelistener(new OnCheckedchangelistener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// Todo Auto-generated method stub
itemsArrayList.get(position).setUcast(isChecked);
}
});
holder.chBoxUcast.setText(itemsArrayList.get(position).getMeno());
holder.chBoxUcast.setChecked(itemsArrayList.get(position).getUcast());
holder.edTBonus.setText(Integer.toString(itemsArrayList.get(position)
.getBonus()));
return convertView;
}
现在一切正常.每次convertView回收时,我都只更改侦听器,并且效果很好.
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