Android 如何使用backbutton取消选中gridview中的所有项?
我正在使用backbutton作为活动的接口,但它对我来说工作不正常,因为在backbutton上显示0大小的arraylist //这里是activity类,我从中获得backbutton接口Android 如何使用backbutton取消选中gridview中的所有项?,android,Android,我正在使用backbutton作为活动的接口,但它对我来说工作不正常,因为在backbutton上显示0大小的arraylist //这里是activity类,我从中获得backbutton接口 public class Multiple_Images extends AppCompatActivity { @Override public void onBackPressed() { if(twice ==true){ Intent intent =n
public class Multiple_Images extends AppCompatActivity {
@Override
public void onBackPressed() {
if(twice ==true){
Intent intent =new Intent(this,MainActivity.class);
startActivity(intent);
}ImageAdapter imageAdapter =new ImageAdapter(this);
imageAdapter.onBackPress();
Toast.makeText(this, "Press twice", Toast.LENGTH_SHORT).show();
twice =true;
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
twice =false; } }, 2000); }}
//这里是适配器类,我正在使用backbutton
public class ImageAdapter extends BaseAdapter implements onBackPressListener {
ArrayList<String> selectedArraylist ;
@Override
public boolean onBackPress() {
selectedArraylist.clear();
Toast.makeText(context, "All values unselected", Toast.LENGTH_SHORT).show();
return true;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
urimodel=new ArrayList<>();
final ImageView imageGrid ;
Activity activity = (Activity) context;
actionMode = activity.startActionMode(new Actionmode());
final GridModel gridModel=(GridModel) this.getItem(i);
if(view==null) {
view = LayoutInflater.from(context).inflate(R.layout.model, null);
selectedArraylist =new ArrayList<>();
}
final CardView cardView= (CardView)view.findViewById(R.id.cardview_image);
imageGrid = (ImageView) view.findViewById(R.id.grid_image);
// gridText = (TextView) view.findViewById(R.id.grid_text);
imageGrid.setScaleType(ImageView.ScaleType.CENTER_CROP);
// imageGrid.setScaleType(ImageView.ScaleType.CENTER_CROP);
Picasso.get().load(gridModel.getImage()).resize(200,200).into(imageGrid);
if (selectedArraylist.contains(gridModel.getImage_text())) {
cardView.setCardBackgroundColor(CARD_SELECTED_COLOR);
}else {
cardView.setCardBackgroundColor(Color.WHITE);
}
return view;
}
}
公共类ImageAdapter扩展BaseAdapter实现onBackPressListener{
ArrayList selectedArraylist;
@凌驾
公共布尔onBackPress(){
selectedArraylist.clear();
Toast.makeText(上下文,“未选择所有值”,Toast.LENGTH_SHORT.show();
返回true;
}
@凌驾
公共视图getView(int i、视图视图、视图组视图组){
urimodel=新的ArrayList();
最终图像视图图像网格;
活动=(活动)上下文;
actionMode=activity.startActionMode(新actionMode());
final GridModel GridModel=(GridModel)this.getItem(i);
如果(视图==null){
视图=LayoutFlater.from(上下文)。充气(R.layout.model,null);
selectedArraylist=新建ArrayList();
}
最终CardView CardView=(CardView)view.findViewById(R.id.CardView\u图像);
imageGrid=(ImageView)view.findViewById(R.id.grid\u image);
//gridText=(TextView)view.findViewById(R.id.grid\u text);
imageGrid.setScaleType(ImageView.ScaleType.CENTER\U裁剪);
//imageGrid.setScaleType(ImageView.ScaleType.CENTER\U裁剪);
Picasso.get().load(gridModel.getImage()).resize(200200).into(imageGrid);
if(selectedArraylist.contains(gridModel.getImage_text())){
设置CardBackgroundColor(选定的卡片颜色);
}否则{
cardView.setCardBackgroundColor(颜色:白色);
}
返回视图;
}
}
非常简单,
我给你我自己的项目代码,希望它能帮助你
StudentFragment.java:
private void MultiSelected_Student(int position) {
Student data = adapter_class.getItem(position);
if (data != null) {
if (selectedIds.contains(data)) selectedIds.remove(data);
else selectedIds.add(data);
}
}
private void Remove_MultiSelected() {
try {
selectedIds.clear();
} catch (Exception e) {
e.printStackTrace();
}
}
public void Group_UnSelect() {
Remove_MultiSelected();
MultiSelected = false;
fab.setVisibility(View.GONE);
homeeActivity.studentsMultiSelect = false;
notifyy();
}
private void notifyy() {
adapter_class.notifyDataSetChanged();
}
HomeActivity.java:
public boolean studentsMultiSelect = false;
@Override
public void onBackPressed() {
if (studentsMultiSelect) {
studentFragment.Group_UnSelect();
} else {
super.onBackPressed();
}
}
很容易,
我给你我自己的项目代码,希望它能帮助你
StudentFragment.java:
private void MultiSelected_Student(int position) {
Student data = adapter_class.getItem(position);
if (data != null) {
if (selectedIds.contains(data)) selectedIds.remove(data);
else selectedIds.add(data);
}
}
private void Remove_MultiSelected() {
try {
selectedIds.clear();
} catch (Exception e) {
e.printStackTrace();
}
}
public void Group_UnSelect() {
Remove_MultiSelected();
MultiSelected = false;
fab.setVisibility(View.GONE);
homeeActivity.studentsMultiSelect = false;
notifyy();
}
private void notifyy() {
adapter_class.notifyDataSetChanged();
}
HomeActivity.java:
public boolean studentsMultiSelect = false;
@Override
public void onBackPressed() {
if (studentsMultiSelect) {
studentFragment.Group_UnSelect();
} else {
super.onBackPressed();
}
}
只需在按下按钮的内部
on中执行此操作
@Override
public void onBackPressed() {
if (twice == true) {
super.onBackPressed(); //this backs to the previous activity, if you want to stay with Intent, add finish() after startActivity()
return;
} else {
for (int i = 0; i < list.size(); i++) {
if (gridView.isItemChecked(i)) {
gridView.setItemChecked(i, false);
}
}
//selectedArraylist.clear(); this is clearing your array of selected items
}
twice = true;
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
twice = false;
}
}, 2000);
}
@覆盖
public void onBackPressed(){
如果(两次==真){
super.onBackPressed();//这返回到上一个活动,如果您想保持意图,请在startActivity()之后添加finish()
返回;
}否则{
对于(int i=0;i
我不知道,你为什么要把
selectedArraylist=newArrayList()适配器getView()
方法中的code>。每次新列表项膨胀时,都会激发getView(),这意味着每次更改适配器源、滚动列表时,都会调用此方法,每次初始化数组时,数组中的所有数据都会丢失。您应该像对待显示项目的工具一样对待适配器类,并且上面的所有操作都是在适配器外部进行的。只需在反压的内部执行即可
@Override
public void onBackPressed() {
if (twice == true) {
super.onBackPressed(); //this backs to the previous activity, if you want to stay with Intent, add finish() after startActivity()
return;
} else {
for (int i = 0; i < list.size(); i++) {
if (gridView.isItemChecked(i)) {
gridView.setItemChecked(i, false);
}
}
//selectedArraylist.clear(); this is clearing your array of selected items
}
twice = true;
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
twice = false;
}
}, 2000);
}
@覆盖
public void onBackPressed(){
如果(两次==真){
super.onBackPressed();//这返回到上一个活动,如果您想保持意图,请在startActivity()之后添加finish()
返回;
}否则{
对于(int i=0;i
我不知道,你为什么要把selectedArraylist=newArrayList()适配器getView()
方法中的code>。每次新列表项膨胀时,都会激发getView(),这意味着每次更改适配器源、滚动列表时,都会调用此方法,每次初始化数组时,数组中的所有数据都会丢失。您应该像对待显示项目的工具一样对待适配器类,上面的所有操作都会在适配器外部执行。感谢您的回复,但在返回时,selectedArraylist显示0大小,这是主要的Issue final ArrayList selectedArraylist=new ArrayList();公共类ImageAdapter扩展了的BaseAdapter{public boolean onBackPress(){/*(int i=0;i因此,当按下后退按钮时,gridview项应该取消选择,但您的selectedArraylist
不应该清除?对我来说,这没有意义,但如果是您的问题,您不应该清除该列表,但您是在imageAdapter.onBackPress()中单独执行此操作的。);
method.Thank你这么多问题都解决了,它又开始工作了,再次感谢+!我添加了几句解释,你做错了什么。基本上,问题是在方法调用中,我只是更改了它,然后它开始工作以供回复,但在返回时,selectedArraylist显示0大小,这是主要的issue final ArrayList selectedArraylist=new ArrayList();公共类ImageAdapter扩展了BaseAdapter{public boolean onBackPress(){/*(int i=0;i因此,当按下后退按钮时,gridview项应该取消选择,但您的selectedArraylist
不应该清除?对我来说,这没有意义,但如果是您的问题,您不应该清除该列表,但您是在imageAdapter.onBackPress()中单独执行此操作的。)
method.非常感谢你,问题解决了,它又开始工作了,再次感谢+!我补充了几句解释,你做错了什么。基本上问题是我