Android simultaneously controls the number of characters input in EditText and prohibits special characters input

This article describes the method of Android controlling the number of EditText input characters and prohibiting special characters input. Share it for your reference. The specific analysis is as follows:

Here are three methods summarized as follows:

Method 1:

1. Reference two namespaces:

import ; 
import ;

Used to prohibit special character input control

Define EditText mEditText object

2. Control character length:

Character length control is implemented through InputFilter filtering. The advantage is that dynamic length control can be achieved instead of a length fixed value

int mMaxLenth = 20;
InputFilter[] FilterArray = new InputFilter[1];
 FilterArray[0] = new InputFilter() {
  @Override
  public CharSequence filter (CharSequence source, int start, int end, 
   Spanned dest, int dstart, int dend){
  boolean bInvlid = false;
  int sourceLen = getCharacterNum(());
  int destLen = getCharacterNum(());
  if (sourceLen + destLen > mMaxLenth) {
   return "";  }
  return source;
  }
 };
(FilterArray);

3. Special character input is prohibited:

 (new TextWatcher() {
  String tmp = "";
  String digits = "/\\:*?<>|\"\n\t";
  @Override
  public void onTextChanged(CharSequence s, int start, int before,
   int count) {
  (());
  }
  @Override
  public void beforeTextChanged(CharSequence s, int start, int count,
   int after) {
  tmp = ();
  }
  @Override
  public void afterTextChanged(Editable s) {
  String str = ();
  if ((tmp)) {
   return;
  }
  StringBuffer sb = new StringBuffer();
  for (int i = 0; i < (); i++) {
   if (((i)) < 0) {
   ((i));
   }
  }
  tmp = ();
  (tmp);
  }
 });

Method 2:

1. Add a reference:

import .*;

2. Define the function:

public static String StringFilter(String str)throws PatternSyntaxException{ 
 String regEx = "[/\\:*?&lt;&gt;|\"\n\t]"; // Characters to be filtered out Pattern p = (regEx); 
 Matcher m = (str); 
 return ("").trim(); 
 }

3. Add listening events:

(new TextWatcher() {
  @Override
  public void onTextChanged(CharSequence s, int start, int before,
   int count) {
  String t = ().toString();
  String editable = ().toString(); 
  String str = stringFilter(()); 
  if(!(str)){ 
   (str); 
   (()); //The cursor is set  } 
  }
  @Override
  public void beforeTextChanged(CharSequence s, int start, int count,
   int after) {
  }
  @Override
  public void afterTextChanged(Editable s) {
  }
 });

Method 3:

int mMaxLenth = 200;//Set the length of characters allowed to enterpublic static String stringFilter(String str)throws PatternSyntaxException{ 
 String regEx = "[/\\:*?&lt;&gt;|\"\n\t]";
 Pattern p = (regEx);
 Matcher m = (str);
 return ("");
 }
(new TextWatcher() {
  private int cou = 0;
  int selectionEnd = 0;
  @Override
  public void onTextChanged(CharSequence s, int start, int before,
   int count) {
  cou = before + count;
  String editable = ().toString();
  String str = stringFilter(editable); //Filter special characters  if (!(str)) {
   (str);
  }
  (());
  cou = ();
  }
  @Override
  public void beforeTextChanged(CharSequence s, int start, int count,
   int after) {
  }
  @Override
  public void afterTextChanged(Editable s) {
  if (cou &gt; mMaxLenth) {
   selectionEnd = ();
   (mMaxLenth, selectionEnd);
  }
  }
 });

All the above codes have been tested and shared with everyone! For the first and second, the two methods will have a problem in Samsung NOTE 2 (there are no problems with other phones), and the input window will jump; for the specific reason, interested friends can debug it!

The third method is fine.

I hope this article will be helpful to everyone's Android programming design.