Answers:
您可以使用TextWatcher查看何时更改了文字
private TextView mTextView;
private EditText mEditText;
private final TextWatcher mTextEditorWatcher = new TextWatcher() {
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
//This sets a textview to the current length
mTextView.setText(String.valueOf(s.length()));
}
public void afterTextChanged(Editable s) {
}
};您使用以下方法将TextWatcher设置为edittext
mEditText.addTextChangedListener(mTextEditorWatcher);您可以使用SupportLibrary v23.1中引入的TextInputLayout包装器（用于EditText）从xml本身进行字符计数
只需用TextInputLayout包装EditText并将CounterEnabled设置为true并设置counterMaxLength。
<android.support.design.widget.TextInputLayout
android:id="@+id/textContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:counterEnabled="true"
app:counterMaxLength="20"
>
<EditText
android:id="@+id/text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Text Hint"
/>
</android.support.design.widget.TextInputLayout>你会得到这样一个重大的影响这
您可以使用counterOverflowTextAppearance和counterTextAppearance来设置计数器样式。
编辑
来自Android文档。
该TextInputEditText提供一流用作此布局的孩子。使用TextInputEditText可以使TextInputLayout更好地控制任何文本输入的视觉效果。用法示例如下：
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.design.widget.TextInputEditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/form_username"/>
</android.support.design.widget.TextInputLayout>您可以使用以下方法TextInputLayout和兼容库：
app:counterEnabled="true"
app:counterMaxLength="420"并完成：
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:counterEnabled="true"
app:counterMaxLength="420">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:maxLength="420" />
</android.support.design.widget.TextInputLayout>在xml中为editText添加此属性
android:maxLength="80"在Java中添加此侦听器
ed_caption.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
tv_counter.setText(80 - s.toString().length() + "/80");
}
});它非常简单，请按照以下说明进行操作：
====将它们添加到您的导入中===
import android.text.Editable;
import android.text.TextWatcher;=====定义此=====
private TextView sms_count;==========内部创建=====
sms_count = (TextView) findViewById(R.id.textView2);
final TextWatcher txwatcher = new TextWatcher() {
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
sms_count.setText(String.valueOf(s.length()));
}
public void afterTextChanged(Editable s) {
}
};
sms_message.addTextChangedListener(txwatcher); You can use TextWatcher class to see text has changed and how much number of character remains.Here i have set counter of 140 characters.
EditText typeMessageToPost;
TextView number_of_character;
public void onCreate(Bundle savedBundleInstance) {
super.onCreate(savedBundleInstance);
setContentView(R.layout.post_activity);
typeMessageToPost.addTextChangedListener(mTextEditorWatcher);
}
private final TextWatcher mTextEditorWatcher=new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
}
@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
number_of_character.setText(String.valueOf(140-s.length()));
}
};只需TextInputLayout在XML文件中设置以下两行即可：
app:counterEnabled="true"
app:counterMaxLength="200"该解决方案使用Kotlin并显示剩余的字符数。另外，如果当前字符数超过了限制50，则文本颜色将变为红色。
科特林
private val mTitleTextWatcher = object : TextWatcher {
override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {}
override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
if(YOUR_EDIT_TEXT_ID.text.toString().trim().length < 51){
YOUR_CHAR_LEFT_TEXTVIEW_ID.text = (50 - YOUR_EDIT_TEXT_ID.text.toString().trim().length).toString()
YOUR_CHAR_LEFT_TEXTVIEW_ID.setTextColor(Color.BLACK)
}
else{
YOUR_CHAR_LEFT_TEXTVIEW_ID.text = "0"
YOUR_CHAR_LEFT_TEXTVIEW_ID.setTextColor(Color.RED)
}
}
override fun afterTextChanged(s: Editable) {}
}另外，别忘了将添加TextWatcher到您的EditText
YOUR_EDIT_TEXT_ID.addTextChangedListener(mTitleTextWatcher)您可以将计数器添加到包装在TextInputLayout中的TextInputEditText中。如您在示例中所看到的，counterEnabled启用此功能并counterMaxLengh为其定义字符数。
<com.google.android.material.textfield.TextInputLayout
android:id="@+id/til_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:counterEnabled="true"
app:counterMaxLength="50">
<com.google.android.material.textfield.TextInputEditText
android:id="@+id/et_title"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</com.google.android.material.textfield.TextInputLayout>我遇到了同样的问题，我尝试了卡梅伦的方法。它可以工作，但是有一个小错误：如果用户使用复制和粘贴，则无法计算字符数。因此，我建议在文本更改后执行以下操作：
private final TextWatcher mTextEditorWatcher = new TextWatcher() {
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
public void afterTextChanged(Editable s) {
//This sets a textview to the current length
mTextView.setText(String.valueOf(s.length()));
}
};使用android：maxLength =“ 140”
那应该工作。:)
希望有帮助
尝试做这样的事情。
与获取CharSequence.length相比，此解决方案可能更高效。每次您点击软键盘时，事件就会触发。因此，如果您进行长度计算，则每次都会计算CharSequence，如果您开始使用大型CharSequnces，这可能会变慢。文本更改上的事件侦听器添加前后计数。这对于增量和减量值非常有效
@Override
public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {
int tick = start + after;
if(tick < mMessageMax) {
int remaining = mMessageMax - tick;
((TextView)findViewById(R.id.contact_us_chars)).setText(String.valueOf(remaining));
}
}试试这个
private TextWatcher textWatcher = new TextWatcher() {
@Override
public void beforeTextChanged(final CharSequence s, final int start, final int count, final int after) {
editText.post(new Runnable() {
@Override
public void run() {
if (length < 100) {
if (count > 0 && after <= 0)/*remove emoij*/ {
length--;
} else if (count > after)/*remove text*/ {
length--;
} else if (count == 0 && after > 1)/*emoij*/ {
++length;
} else if (count == 0 && after == 1)/*Text*/ {
++length;
} else if (count > 0 && after > 1) {
++length;
}
if (s.length() <= 0)
length = 0;
Log.w("MainActivity", " Length: " + length);
} else {
if (count > 0 && after <= 0)/*remove emoij*/ {
length--;
} else if (count > after)/*remove text*/ {
length--;
}
Log.w("MainActivity", " Length: " + length);
}
if (length == 100) {
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(s.length())});
} else {
editText.setFilters(new InputFilter[]{});
}
}
});
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
}
};`
思路清晰；
abstract class CharacterWatcher : TextWatcher {
override fun afterTextChanged(text: Editable?) {
afterCharacterChanged(text?.lastOrNull(), text?.length)
}
override fun beforeTextChanged(text: CharSequence?, start: Int, count: Int, before: Int) {}
override fun onTextChanged(text: CharSequence?, start: Int, before: Int, count: Int) {}
abstract fun afterCharacterChanged(char: Char?, count: Int?)
}
editText.addTextChangedListener(new CharacterWatcher() {
@Override
public void afterCharacterChanged(@Nullable Character character, @Nullable Integer count) {
action()
}
});