android listview setAdapter（)方法导致闪退

Question

代码如下，想要实现点击一个checkBox之后，弹出一个dialog，其中用listview来显示带有图标和应用信息的列表，但是运行之后会闪退，提示
listview.setAdapter(browseAppAdapter);
这行代码空指针错误，求解

            checkBox.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if (checkBox.isChecked()) {
                    final Dialog dialog = new Dialog(getActivity());
                    dialog.setContentView(R.layout.browse_app_list);
                    dialog.setTitle("应用列表");

                    mlistAppInfo = new ArrayList<AppInfo>();
                    queryAppInfo(); // 查询所有应用程序信息
                    BrowseApplicationInfoAdapter browseAppAdapter = new BrowseApplicationInfoAdapter(
                            getActivity(), mlistAppInfo);   
                    listview.setAdapter(browseAppAdapter);
                    listview.setOnItemClickListener(new OnItemClickListener(){
                        @Override
                        public void onItemClick(AdapterView<?> arg0, View arg1,
                                int position, long arg3) {
                            // TODO Auto-generated method stub
                            intent = mlistAppInfo.get(position).getIntent();
                        }

                    });
                    dialog.show();
                }
            }
        });

Answer 1

listview实例化了吗？