限制EditText
Android中文本长度的最佳方法是什么?
有没有办法通过xml做到这一点?
限制EditText
Android中文本长度的最佳方法是什么?
有没有办法通过xml做到这一点?
Answers:
maxLength
属性仍然有效。
android:maxLength
它等效于InputFilter.LengthFilter
,因此以编程方式更改其过滤器时,您还修改了其XML过滤器。
setFilters
将停止android:maxLength
工作,因为它会覆盖XML设置的过滤器。换句话说,如果以编程方式设置任何过滤器,则必须以编程方式设置所有过滤器。
使用输入过滤器限制文本视图的最大长度。
TextView editEntryView = new TextView(...);
InputFilter[] filterArray = new InputFilter[1];
filterArray[0] = new InputFilter.LengthFilter(8);
editEntryView.setFilters(filterArray);
InputFilter
。它android:maxlength
在xml文件中覆盖,因此我们需要添加LengthFilter
这种方式。
EditText editText = new EditText(this);
int maxLength = 3;
editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});
TextWatcher
。
一个注谁正在使用一个自定义的输入滤波器和人民也希望限制最大长度:
当您在代码中分配输入过滤器时,将清除所有先前设置的输入过滤器,包括带有的一组输入过滤器android:maxLength
。我在尝试使用自定义输入过滤器来防止使用某些我们在密码字段中不允许的字符时发现了这一点。使用setFilters设置该过滤器后,不再观察到maxLength。解决方案是通过编程将maxLength和我的自定义过滤器一起设置。像这样:
myEditText.setFilters(new InputFilter[] {
new PasswordCharFilter(), new InputFilter.LengthFilter(20)
});
TextView tv = new TextView(this);
tv.setFilters(new InputFilter[]{ new InputFilter.LengthFilter(250) });
我遇到了这个问题,我认为我们缺少一种以编程方式很好地说明这一点而又不会丢失已经设置的过滤器的方法。
在XML中设置长度:
正确地接受了答案,如果您想为EditText定义一个固定的长度,并且以后不再更改,只需在EditText XML中进行定义:
android:maxLength="10"
以编程方式设置长度
要以编程方式设置长度,您需要通过进行设置InputFilter
。但是,如果您创建一个新的InputFilter并将其设置为,EditText
则会丢失您可能已通过XML或以编程方式添加的所有其他已定义的过滤器(例如maxLines,inputType等)。
所以这是错误的:
editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});
为避免丢失以前添加的过滤器,您需要获取这些过滤器,添加新的过滤器(在这种情况下为maxLength),然后将过滤器设置回EditText
如下:
爪哇
InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength);
editText.setFilters(newFilters);
但是Kotlin使每个人都更容易,您还需要将过滤器添加到已经存在的过滤器中,但是您可以通过以下简单的方法来实现:
editText.filters += InputFilter.LengthFilter(maxLength)
对于想知道如何实现此目标的其他人,这里是我的扩展EditText
课程EditTextNumeric
。
.setMaxLength(int)
-设置最大位数
.setMaxValue(int)
-限制最大整数值
.setMin(int)
-限制最小整数值
.getValue()
-获取整数值
import android.content.Context;
import android.text.InputFilter;
import android.text.InputType;
import android.widget.EditText;
public class EditTextNumeric extends EditText {
protected int max_value = Integer.MAX_VALUE;
protected int min_value = Integer.MIN_VALUE;
// constructor
public EditTextNumeric(Context context) {
super(context);
this.setInputType(InputType.TYPE_CLASS_NUMBER);
}
// checks whether the limits are set and corrects them if not within limits
@Override
protected void onTextChanged(CharSequence text, int start, int before, int after) {
if (max_value != Integer.MAX_VALUE) {
try {
if (Integer.parseInt(this.getText().toString()) > max_value) {
// change value and keep cursor position
int selection = this.getSelectionStart();
this.setText(String.valueOf(max_value));
if (selection >= this.getText().toString().length()) {
selection = this.getText().toString().length();
}
this.setSelection(selection);
}
} catch (NumberFormatException exception) {
super.onTextChanged(text, start, before, after);
}
}
if (min_value != Integer.MIN_VALUE) {
try {
if (Integer.parseInt(this.getText().toString()) < min_value) {
// change value and keep cursor position
int selection = this.getSelectionStart();
this.setText(String.valueOf(min_value));
if (selection >= this.getText().toString().length()) {
selection = this.getText().toString().length();
}
this.setSelection(selection);
}
} catch (NumberFormatException exception) {
super.onTextChanged(text, start, before, after);
}
}
super.onTextChanged(text, start, before, after);
}
// set the max number of digits the user can enter
public void setMaxLength(int length) {
InputFilter[] FilterArray = new InputFilter[1];
FilterArray[0] = new InputFilter.LengthFilter(length);
this.setFilters(FilterArray);
}
// set the maximum integer value the user can enter.
// if exeeded, input value will become equal to the set limit
public void setMaxValue(int value) {
max_value = value;
}
// set the minimum integer value the user can enter.
// if entered value is inferior, input value will become equal to the set limit
public void setMinValue(int value) {
min_value = value;
}
// returns integer value or 0 if errorous value
public int getValue() {
try {
return Integer.parseInt(this.getText().toString());
} catch (NumberFormatException exception) {
return 0;
}
}
}
用法示例:
final EditTextNumeric input = new EditTextNumeric(this);
input.setMaxLength(5);
input.setMaxValue(total_pages);
input.setMinValue(1);
EditText
当然,适用于的所有其他方法和属性也可以工作。
由于goto10的观察,我将以下代码放在一起,以防止通过设置最大长度而丢失其他过滤器:
/**
* This sets the maximum length in characters of an EditText view. Since the
* max length must be done with a filter, this method gets the current
* filters. If there is already a length filter in the view, it will replace
* it, otherwise, it will add the max length filter preserving the other
*
* @param view
* @param length
*/
public static void setMaxLength(EditText view, int length) {
InputFilter curFilters[];
InputFilter.LengthFilter lengthFilter;
int idx;
lengthFilter = new InputFilter.LengthFilter(length);
curFilters = view.getFilters();
if (curFilters != null) {
for (idx = 0; idx < curFilters.length; idx++) {
if (curFilters[idx] instanceof InputFilter.LengthFilter) {
curFilters[idx] = lengthFilter;
return;
}
}
// since the length filter was not part of the list, but
// there are filters, then add the length filter
InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
newFilters[curFilters.length] = lengthFilter;
view.setFilters(newFilters);
} else {
view.setFilters(new InputFilter[] { lengthFilter });
}
}
//Set Length filter. Restricting to 10 characters only
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH)});
//Allowing only upper case characters
editText.setFilters(new InputFilter[]{new InputFilter.AllCaps()});
//Attaching multiple filters
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH), new InputFilter.AllCaps()});
Xml
android:maxLength="10"
Java:
InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength);
editText.setFilters(newFilters);
科特林:
editText.filters += InputFilter.LengthFilter(maxLength)
在material.io中,您可以TextInputEditText
结合使用TextInputLayout
:
<com.google.android.material.textfield.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:counterEnabled="true"
app:counterMaxLength="1000"
app:passwordToggleEnabled="false">
<com.google.android.material.textfield.TextInputEditText
android:id="@+id/edit_text"
android:hint="@string/description"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:maxLength="1000"
android:gravity="top|start"
android:inputType="textMultiLine|textNoSuggestions"/>
</com.google.android.material.textfield.TextInputLayout>
您可以使用drawable配置密码EditText:
或者,您可以使用/不使用计数器来限制文本长度:
依赖关系:
implementation 'com.google.android.material:material:1.1.0-alpha02'
XML格式
android:maxLength="10"
以编程方式:
int maxLength = 10;
InputFilter[] filters = new InputFilter[1];
filters[0] = new InputFilter.LengthFilter(maxLength);
yourEditText.setFilters(filters);
注意:在内部,EditText和TextView解析android:maxLength
XML中的值并用于InputFilter.LengthFilter()
应用它。
这是一个自定义EditText类,它允许Length过滤器与其他过滤器一起使用。感谢Tim Gallagher的回答(下)
import android.content.Context;
import android.text.InputFilter;
import android.util.AttributeSet;
import android.widget.EditText;
public class EditTextMultiFiltering extends EditText{
public EditTextMultiFiltering(Context context) {
super(context);
}
public EditTextMultiFiltering(Context context, AttributeSet attrs) {
super(context, attrs);
}
public EditTextMultiFiltering(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public void setMaxLength(int length) {
InputFilter curFilters[];
InputFilter.LengthFilter lengthFilter;
int idx;
lengthFilter = new InputFilter.LengthFilter(length);
curFilters = this.getFilters();
if (curFilters != null) {
for (idx = 0; idx < curFilters.length; idx++) {
if (curFilters[idx] instanceof InputFilter.LengthFilter) {
curFilters[idx] = lengthFilter;
return;
}
}
// since the length filter was not part of the list, but
// there are filters, then add the length filter
InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
newFilters[curFilters.length] = lengthFilter;
this.setFilters(newFilters);
} else {
this.setFilters(new InputFilter[] { lengthFilter });
}
}
}
xml中的简单方法:
android:maxLength="4"
如果您需要在xml编辑文本中设置4个字符,请使用此
<EditText
android:id="@+id/edtUserCode"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxLength="4"
android:hint="Enter user code" />
这很好用...
android:maxLength="10"
这将只接受10
字符。
以编程方式尝试Java:
myEditText(new InputFilter[] {new InputFilter.LengthFilter(CUSTOM_MAX_LEN)});
myEditText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(CUSTOM_MAX_LEN)});
我看到了很多不错的解决方案,但是我想给出一个我认为更完整,更友好的解决方案,其中包括:
1,极限长度。
2,如果输入更多,请回调以触发吐司。
3,光标可以在中间或尾部。
4,用户可以通过粘贴字符串输入。
5,始终丢弃溢出输入并保持原点。
public class LimitTextWatcher implements TextWatcher {
public interface IF_callback{
void callback(int left);
}
public IF_callback if_callback;
EditText editText;
int maxLength;
int cursorPositionLast;
String textLast;
boolean bypass;
public LimitTextWatcher(EditText editText, int maxLength, IF_callback if_callback) {
this.editText = editText;
this.maxLength = maxLength;
this.if_callback = if_callback;
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (bypass) {
bypass = false;
} else {
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append(s);
textLast = stringBuilder.toString();
this.cursorPositionLast = editText.getSelectionStart();
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
if (s.toString().length() > maxLength) {
int left = maxLength - s.toString().length();
bypass = true;
s.clear();
bypass = true;
s.append(textLast);
editText.setSelection(this.cursorPositionLast);
if (if_callback != null) {
if_callback.callback(left);
}
}
}
}
edit_text.addTextChangedListener(new LimitTextWatcher(edit_text, MAX_LENGTH, new LimitTextWatcher.IF_callback() {
@Override
public void callback(int left) {
if(left <= 0) {
Toast.makeText(MainActivity.this, "input is full", Toast.LENGTH_SHORT).show();
}
}
}));
我没有做的是,如果用户突出显示当前输入的一部分并尝试粘贴很长的字符串,我不知道如何恢复突出显示。
例如,最大长度设置为10,用户输入了“ 12345678”,并将“ 345”标记为突出显示,并尝试粘贴将超出限制的字符串“ 0000”。
当我尝试使用edit_text.setSelection(start = 2,end = 4)恢复原点状态时,结果是,它仅插入2个空格作为“ 12 345 678”,而不是原点突出显示。我希望有人解决这个问题。
科特林:
edit_text.filters += InputFilter.LengthFilter(10)
ZTE Blade A520
有奇怪的效果。当您键入10个以上的符号(例如15个)时,EditText
显示前10 个符号,但其他5个不可见且不可访问。但是,当您使用删除符号时Backspace
,它会先删除正确的5个符号,然后再删除剩余的10个符号。要解决此问题,请使用以下解决方案:
android:inputType="textNoSuggestions|textVisiblePassword"
android:maxLength="10"
或这个:
android:inputType="textNoSuggestions"
或者,如果您想提出建议:
private class EditTextWatcher(private val view: EditText) : TextWatcher {
private var position = 0
private var oldText = ""
override fun afterTextChanged(s: Editable?) = Unit
override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
oldText = s?.toString() ?: ""
position = view.selectionStart
}
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
val newText = s?.toString() ?: ""
if (newText.length > 10) {
with(view) {
setText(oldText)
position = if (start > 0 && count > 2) {
// Text paste in nonempty field.
start
} else {
if (position in 1..10 + 1) {
// Symbol paste in the beginning or middle of the field.
position - 1
} else {
if (start > 0) {
// Adding symbol to the end of the field.
start - 1
} else {
// Text paste in the empty field.
0
}
}
}
setSelection(position)
}
}
}
}
// Usage:
editTextWatcher = EditTextWatcher(view.edit_text)
view.edit_text.addTextChangedListener(editTextWatcher)
xml中的简单方法:
android:maxLength="@{length}"
以编程方式设置它,您可以使用以下功能
public static void setMaxLengthOfEditText(EditText editText, int length) {
InputFilter[] filters = editText.getFilters();
List arrayList = new ArrayList();
int i2 = 0;
if (filters != null && filters.length > 0) {
int length = filters.length;
int i3 = 0;
while (i2 < length) {
Object obj = filters[i2];
if (obj instanceof LengthFilter) {
arrayList.add(new LengthFilter(length));
i3 = 1;
} else {
arrayList.add(obj);
}
i2++;
}
i2 = i3;
}
if (i2 == 0) {
arrayList.add(new LengthFilter(length));
}
if (!arrayList.isEmpty()) {
editText.setFilters((InputFilter[]) arrayList.toArray(new InputFilter[arrayList.size()]));
}
}