ExpandableListView子项删除按钮点击始终获取最后一条数据问题

出现点击删除按钮永远获取到最后一个子项数据的问题，核心是变量作用域使用错误：

• 你把txtBCN、txtmvpID、removeMVP甚至计数用的ctrVisit都定义成了Activity层面的全局变量。ExpandableListView和普通ListView一样通过View复用机制渲染列表项，每渲染一个子项就会执行一次getChildView方法，这些全局变量会被反复赋值为当前正在渲染的子项控件实例。等列表全部渲染完成，这些全局变量存的永远是最后一个子项的控件引用，不管你点击哪个位置的删除按钮，取到的都是最后一项的数据。
• 你的代码里还存在两个附带问题：一是fillData方法中if和else分支的代码完全重复，属于无意义冗余；二是COA.equals(0)判断永远不会生效，因为COA是字符串类型，和整数0做equals比较永远返回false。

核心修改逻辑是把所有和单个列表项绑定的控件、数据都改成方法内的局部变量，不要用全局变量存储单item的状态：

1. 将子项控件声明全部移到getChildView方法内部，作为局部变量存在
2. 绑定子项View时，提前把当前项需要用到的分支名称、MVPID等数据存为final局部变量，点击事件触发时直接使用这些提前存好的值，不要等点击时再去全局控件里取
3. 清理fillData里的冗余代码，修正无效的条件判断

修复后的核心代码 #

优化后的fillData方法 #

private void fillData(){
    int COA = dataBaseHelper.getCount(VisitDate);
    mGroupsCursor = dataBaseHelper.getSelectedParentMVPDate(reformatMVPDate());
    startManagingCursor(mGroupsCursor);
    mGroupsCursor.moveToFirst();
    ExpandableListView SelectedListView = (ExpandableListView) findViewById(R.id.MVPListitem);
    mAdapter = new MyExpandableListAdapter(mGroupsCursor, this,
            R.layout.mvp_list_parent,
            R.layout.mvp_list_child,
            new String[]{DataBaseHelper.MVP_INDUSTRY_TYPE},
            new int[]{R.id.txtMVPParent},
            new String[]{DataBaseHelper.MVP_BRCH_CODE_NAME, DataBaseHelper.MVP_BRCH_ADDRESS, DataBaseHelper.MVP_ID},
            new int[]{R.id.txtviewBrnchCodeName, R.id.txtviewBrchAddr, R.id.txtmvpID});
    SelectedListView.setAdapter(mAdapter);
}

修复后的getChildView方法 #

@Override
public View getChildView(final int groupPosition,
                         final int childPosition, boolean isLastChild, View convertView,
                         ViewGroup parent) {

    View rowView = super.getChildView(groupPosition, childPosition,
            isLastChild, convertView, parent);

    // 所有子项控件声明为方法内局部变量，禁止使用全局变量存储单item控件
    Button removeMVP = (Button) rowView.findViewById(R.id.btnRemove);
    TextView txtBCN = (TextView) rowView.findViewById(R.id.txtviewBrnchCodeName);
    TextView txtBA = (TextView) rowView.findViewById(R.id.txtviewBrchAddr);
    TextView txtmvpID = (TextView) rowView.findViewById(R.id.txtmvpID);

    // 提前将当前项需要用到的数据存为final局部变量，点击时直接取用
    final String currentBranchName = txtBCN.getText().toString();
    final String currentMvpId = txtmvpID.getText().toString();

    if(edit.getVisibility() == View.VISIBLE){
        removeMVP.setVisibility(View.GONE);
    } else {
        removeMVP.setVisibility(View.VISIBLE);
    }

    removeMVP.setOnClickListener(new View.OnClickListener() {
        @SuppressLint("Range")
        public void onClick(View v) {
            AlertDialog.Builder builder = new AlertDialog.Builder(MasterVisitPlan.this);
            builder.setTitle("Delete Appointment")
                    .setMessage("Are you sure? Assigned date and branch will be removed." + currentBranchName)
                    .setCancelable(false)
                    .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Cursor res = dataBaseHelper.getCounterVisitData(currentBranchName, reformatDate());
                            // 计数变量也改为局部变量，避免全局变量值错乱
                            String ctrVisit = "0";
                            if(res.getCount() != 0){
                                while (res.moveToNext()){
                                    ctrVisit = res.getString(3);
                                }
                                int diffCounterVisit = Integer.parseInt(ctrVisit) - 1;
                                dataBaseHelper.updateCounterVisit(currentBranchName,String.valueOf(diffCounterVisit),reformatDate());
                            }
                            Integer deletedRows = dataBaseHelper.DeleteSelectedChildMVPDate(currentMvpId);
                            if(deletedRows > 0){
                                AlertDialog.Builder builder = new AlertDialog.Builder(MasterVisitPlan.this);
                                builder.setMessage("✔ Successfully removed.")
                                        .setCancelable(false)
                                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                                            @Override
                                            public void onClick(DialogInterface dialog, int which) {
                                                edit.clearAnimation();
                                                dialog.cancel();
                                                setMonthView();
                                                getStatus();
                                                btnViewfromUploadStatus();
                                                enableView(calendar, false);
                                            }
                                        });
                                AlertDialog dialogDeleted = builder.create();
                                dialogDeleted.show();
                            }else{
                                Toast.makeText(MasterVisitPlan.this, "Data not Deleted", Toast.LENGTH_SHORT).show();
                            }
                            fillData();
                            countMVPData();
                        }
                    })
                    .setNegativeButton("No", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.cancel();
                        }
                    });
            AlertDialog dialog = builder.create();
            dialog.show();
        }
    });
    return rowView;
}

额外提醒：startManagingCursor方法从API 11开始已被废弃，后续维护建议替换为CursorLoader实现，避免Cursor生命周期管理不当引发内存泄漏。

内容的提问来源于stack exchange，提问作者Ryan Baltazar