我的代码的结构使得“抽屉 Activity ” 调用多个 fragment 抽屉之一，每个 fragment 抽屉包含一个 fragment 项目列表，这些 fragment 项目使用 ItemAdapter创建 fragment 列表。
我的主要问题是我一直在尝试检索 EditText与 afterTextChanged()在项目适配器中，但总是得到 NullPointerException我希望能够检索用户刚刚输入的值。
非常感谢以文明方式提出的任何和所有建议。
抽屉 Activity
public class Drawers extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
public static boolean isSealBroken;
public static int DrawerChosen;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
System.out.println(savedInstanceState);
setContentView(R.layout.activity_drawers);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.screen_area, new drawer_top_Fragment());
ft.commit();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.drawers, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
Fragment fragment = null;
int id = item.getItemId();
//Find ID for buttons in Drawers Navigation bar and connect it to the correct fragment
if (id == R.id.nav_drawer_top) {
fragment = new drawer_top_Fragment();
} else if (id == R.id.nav_drawer_med) {
if (isSealBroken == false) {
isSealBroken_Message();
}
if (isSealBroken == true) {
fragment = new drawer_med_Fragment();
DrawerChosen=1;
}
}
else if(id == R.id.nav_drawer1) {
if(isSealBroken==false){
isSealBroken_Message();
if(isSealBroken==true){
fragment = new drawer1_Fragment();
DrawerChosen=2;
}
}else {
fragment = new drawer1_Fragment();
DrawerChosen=2;
}
}
else if(id == R.id.nav_drawer2) {
if(isSealBroken==false){
isSealBroken_Message();
if(isSealBroken==true){
fragment = new drawer2_Fragment();
DrawerChosen=3;
}
}else {
fragment = new drawer2_Fragment();
DrawerChosen=3;
}
}
// more of the same until nav 8
else if(id == R.id.nav_drawer8) {
if(isSealBroken==false){
isSealBroken_Message();
if(isSealBroken==true){
fragment = new drawer8_Fragment();
DrawerChosen=9;
}
}else {
fragment = new drawer8_Fragment();
DrawerChosen=9;
}
}
else if (id == R.id.drawer_continue) {
final Intent intent = new Intent(this, WagonSummary.class);
new AlertDialog.Builder(this)
.setTitle("Er Skráningu hluta á vagni lokið?")
.setNegativeButton("Nei",null)
.setPositiveButton("já",new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// FinishComputeList(); // calls upon class to compute value from list
startActivity(intent);
}
}).create().show();
} else if (id == R.id.drawer_comment) {
Intent intent = new Intent(this, CommentSummary.class);
startActivity(intent);
}
if(fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.screen_area, fragment);
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
public void isSealBroken_Message()
{
new AlertDialog.Builder(this)
.setTitle("Er innsigli rofið?")
.setNegativeButton("Nei",null)
.setPositiveButton("já",new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
isSealBroken=true;
ListProcessing d = new ListProcessing();
d.sealBroken();
}
}).create().show();
}
}
以其中一个抽屉 fragment 为例
public class drawer3_Fragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.word_list, container, false);
getActivity().setTitle(R.string.drawer_three);
ArrayList<Item> items = new ArrayList<Item>();
String[] itemArr = getResources().getStringArray(R.array.drawer_three_items);
int[] quantityArr = getResources().getIntArray(R.array.drawer_three_quantity);
String[] typeArr = getResources().getStringArray(R.array.drawer_three_type);
String item;
int quantity;
String type;
for (int i = 0; i < itemArr.length; i++) {
item = itemArr[i];
quantity = quantityArr[i];
type = typeArr[i];
items.add(new Item(item, quantity, type));
}
ItemAdapter adapter = new ItemAdapter(getActivity(), items);
ListView listView = (ListView) rootView.findViewById(R.id.list);
listView.setAdapter(adapter);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
}
元素适配器
public class ItemAdapter extends ArrayAdapter<Item> {
public ItemAdapter(Activity context, ArrayList<Item> items) {
super(context, 0, items);
}
@Override
public View getView(final int position, final View convertView, final ViewGroup parent){
// Check if the existing view is being reused, otherwise inflate the view
View listItemView = convertView;
if(listItemView == null) {
listItemView = LayoutInflater.from(getContext()).inflate(
R.layout.list_item, parent, false);
}
// Get the {@link Item} object located at this position in the list
final Item currentItem = getItem(position);
final Item currentposs = getItem(position);
// Find the TextView in the list_item.xml layout with the ID version_name
TextView itemTextView = (TextView) listItemView.findViewById(R.id.item);
// Get the version name from the current object and
// set this text on the name TextView
itemTextView.setText(currentItem.getItem());
TextView infoTextView = (TextView) listItemView.findViewById(R.id.info);
infoTextView.setText(currentItem.getInfo());
TextView doseTextView = (TextView) listItemView.findViewById(R.id.dose);
doseTextView.setText(currentItem.getDose());
TextView quantityTextView = (TextView) listItemView.findViewById(R.id.quantity);
quantityTextView.setText(currentItem.getQuantity());
TextView typeTextView = (TextView) listItemView.findViewById(R.id.type);
typeTextView.setText(currentItem.getType());
CheckBox check = listItemView.findViewById(R.id.checkbox);
//reset and Populating list
final String itemName= currentposs.getItem();
String itemInfo = currentposs.getInfo();
String itemDose = currentposs.getDose();
String itemQuantity = currentposs.getQuantity();
String itemType = currentposs.getType();
// populateList(position,itemName,itemInfo,itemDose,itemQuantity,itemType);
final View listItemView1 = listItemView;
// when chekbox is ticked then list is amended
check.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
CheckBox checkBox = (CheckBox) v;
if (checkBox.isChecked()) {
// to see if correct location is beaing chosen each time
System.out.println("currentposs : "+currentposs);
System.out.println("position : "+position);
System.out.println("Parent : "+parent);
String itemName= currentposs.getItem();
System.out.println("getItem() : "+itemName);
String itemInfo = currentposs.getInfo();
System.out.println("getInfo() : "+ itemInfo);
String itemDose = currentposs.getDose();
System.out.println("getDose() : "+ itemDose);
String itemType = currentposs.getType();
System.out.println("getType() : "+ itemType);
String itemQuantity = currentposs.getQuantity();
System.out.println("getQuantity() : "+ itemQuantity);
int wagonNr = 0;
String status = "false";
ListProcessing d = new ListProcessing();
d.itemStatusChange( wagonNr,Drawers.DrawerChosen,position,status);
}
}
});
//TextView.setContentView(R.layout.list_item);
//String yourEditText = (EditText) currentposs.findViewById(R.id.quantity);
final View finalListItemView = listItemView;
quantityTextView.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
//nothing has worked
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
//nothing has worked
}
@Override
public void afterTextChanged(Editable s) {
//nothing has worked but here are some exaples of what i have tried
//TextView quantityTextViewEdited = (TextView) convertView.findViewById(R.id.quantity);
// String n = (String) currentItem.getText();
// View listItemView2 = convertView;
// EditText name=(EditText)listItemView2.findViewById(R.id.quantity);
// String a=name.getText().toString().trim();
//
View listItemView2 = listItemView1;
TextView quantityTextView2 = (TextView) listItemView2.findViewById(R.id.quantity);
int numberInserted = Log.e("input text", quantityTextView2.getText().toString());
System.out.println("Changed qunatity: "+ numberInserted);
}
});
if (currentItem.isCheckBox()) {
check.setVisibility(View.VISIBLE);
} else {
check.setVisibility(View.GONE);
}
if (currentItem.isInfo()) {
infoTextView.setVisibility(View.VISIBLE);
} else {
infoTextView.setVisibility(View.GONE);
}
if (currentItem.isDose()) {
doseTextView.setVisibility(View.VISIBLE);
} else {
doseTextView.setVisibility(View.GONE);
}
if (currentItem.isQuantity()) {
quantityTextView.setVisibility(View.VISIBLE);
} else {
quantityTextView.setVisibility(View.GONE);
}
return listItemView;
}
元素
public class Item {
private String item;
private String info;
private String dose;
private String type;
private int quantity;
private boolean isInfo = false;
private boolean isDose = false;
private boolean isQuantity = false;
private boolean isCheckBox = false;
/**
* @param wItem
*/
public Item(String wItem) {
item = wItem;
isCheckBox = true;
}
/**
* @param wItem is the name of the item/medicine
* @param wQuantity is how many items there should be total
* @param wType ...
*/
public Item(String wItem, int wQuantity, String wType) {
item = wItem;
quantity = wQuantity;
type = wType;
isCheckBox = true;
isQuantity = true;
}
public Item(String wItem, String wInfo, String wDose, int wQuantity, String wType) {
item = wItem;
info = wInfo;
dose = wDose;
quantity = wQuantity;
type = wType;
isCheckBox = true;
isQuantity = true;
isDose = true;
isInfo = true;
}
public String getItem() {
return item;
}
public String getInfo() {
return info;
}
public String getDose() {
return dose;
}
public String getType() {
return type;
}
public String getQuantity() {
return Integer.toString(quantity);
}
public boolean isCheckBox() {
return isCheckBox;
}
public boolean isInfo() {
return isInfo;
}
public boolean isDose() {
return isDose;
}
public boolean isQuantity() {
return isQuantity;
}
public void findViewById (int quantity) {
}
更新 输入后 Log.e("input text", quantityTextView2.getText().toString());当用户输入新数字时，在“afterTextChanged”内，然后在终端中打印正确的用户输入。当试图将其封装在一个 int 变量中时，它只会返回数字 14，无论用户输入如何。
来自运行终端的例子
D/InputMethodManager: SSI - flag : 0 Pid : 16988 view : com.example.notandi.hospitalwagons
D/ViewRootImpl@be26588[PopupWindow:b7449a5]: Relayout returned: old=[622,841][712,949] new=[655,841][745,949] result=0x1 surface={valid=true 493809848320} changed=false
D/ViewRootImpl@3142bca[Drawers]: ViewPostIme key 0
I/System.out: !!!!!!!!!!!!!!!!!!!!!!afterTextChanged!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I/System.out: Changed qunatity: 13
I/System.out: !!!!!!!!!!!!!!!!!!!!!!afterTextChanged!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I/System.out: Changed qunatity: 13
D/ViewRootImpl@3142bca[Drawers]: ViewPostIme key 1
D/OpenGLRenderer: eglDestroySurface = 0x73093dc320
D/ViewRootImpl@be26588[PopupWindow:b7449a5]: dispatchDetachedFromWindow
D/InputEventReceiver: channel '9bf6f1 PopupWindow:b7449a5 (client)' ~ Disposing input event receiver.
D/InputEventReceiver: channel '9bf6f1 PopupWindow:b7449a5 (client)' ~NativeInputEventReceiver.
I/System.out: !!!!!!!!!!!!!!!!!!!!!!afterTextChanged!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
E/input text: 2
I/System.out: Changed qunatity: 14
I/System.out: !!!!!!!!!!!!!!!!!!!!!!afterTextChanged!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
E/input text: 2
I/System.out: Changed qunatity: 14
更新 2
它活了!! 由于用户 Nirav Bhavsar 的有用推荐，我探索了控制台日志方法并将以下代码插入到“onTextChanged”中
String numberInserted ;
final View listItemView2 = listItemView1;
final TextView quantityTextView2 = (TextView) listItemView2.findViewById(R.id.quantity);
String userinput = quantityTextView2.getText().toString();
System.out.println("user input: "+userinput);
它有效，我能够检索用户插入的 EditText 值。非常感谢堆栈溢出社区。
最佳答案
I want to be able to retrieve the value that the user has just put in
给你，
final View finalListItemView = listItemView;
quantityTextView.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
//nothing has worked
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
//here "s" is the latest text
Toast.makeText(getApplicationContext(),s,Toast.LENGTH_SHORT).show();
}
@Override
public void afterTextChanged(Editable s) {
//don't do anything here, instead
//get the lastest text in onTextChanged()
}
});
现在，为什么会出现 NullPointerException？
因为你必须在 listItemView 中找到 View R.id.quantity 而不是在 convertView 和 listItemView2 中afterTextChanged()。
//e.g
EditText name=(EditText)listItemView2.findViewById(R.id.quantity);
此外，我想知道为什么不制作 quantityTextView final 并在 afterTextChanged() 中使用？
关于android - 如何从 fragment 列表中的 EditText 获取用户输入？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51751222/