Android---3种方式限制EditView输入字数

方法一：利用TextWatcher

editText.addTextChangedListener(new TextWatcher() {  
           private CharSequence temp;  
           private boolean isEdit = true;  
           private int selectionStart ;  
           private int selectionEnd ;  
           @Override 
           public void beforeTextChanged(CharSequence s, int arg1, int arg2,  
                   int arg3) {  
               temp = s;  
           }  
             
           @Override 
           public void onTextChanged(CharSequence s, int arg1, int arg2,  
                   int arg3) {  
           }  
             
           @Override 
           public void afterTextChanged(Editable s) {  
                selectionStart = editText.getSelectionStart();  
               selectionEnd = editText.getSelectionEnd();  
               Log.i("gongbiao1",""+selectionStart);  
               if (temp.length() > Constant.TEXT_MAX) {  
                   Toast.makeText(KaguHomeActivity.this,  
                           R.string.edit_content_limit, Toast.LENGTH_SHORT)  
                           .show();  
                   s.delete(selectionStart-1, selectionEnd);  
                   int tempSelection = selectionStart;  
                   editText.setText(s);  
                   editText.setSelection(tempSelection);  
               }  
           }  
 
 
       }); 

 private TextWatcher mTextWatcher = new TextWatcher(){
  Toast mToast = null;
  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) {
   int nSelStart = 0;
   int nSelEnd = 0;
   boolean nOverMaxLength = false;
   
   nSelStart = mEditText.getSelectionStart();
   nSelEnd   = mEditText.getSelectionEnd();
   
   nOverMaxLength = (s.length() > Constants.MAX_TEXT_INPUT_LENGTH) ? true : false;
   if(nOverMaxLength){
    if(null == mToast){
     mToast = Toast.makeText(mContext,
       R.string.IDS_MSG_TEXT_OVER_MAXLENGTH,
       Toast.LENGTH_SHORT);
    }
    mToast.show();
    
    s.delete(nSelStart - 1, nSelEnd);

    mEditText.setTextKeepState(s);//请读者注意这一行，保持光标原先的位置，而 mEditText.setText(s)会让光标跑到最前面，

                                                     //就算是再加mEditText.setSelection(nSelStart) 也不起作用
    }
  }
 };

方法二：利用InputFilter

    

editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(100)});  //其中100最大输入字数 

editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(100)});  //其中100最大输入字数

方法三：在XML中设定

Xml代码
<EditText 
    .  
    .  
    .  
    Android:maxLength="100" 
/> 

 

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方法二：
         利用EditText可以设置filter的特性，自定义一个LengthFilter，当输入字数超过限制时 ，做出自定义的提示
          // 输入框限制输入字数
        InputFilter[] filters = new InputFilter[1];
        filters[0] = new InputFilter.LengthFilter(Constant.TEXT_MAX) {
            @Override
            public CharSequence filter(CharSequence source, int start, int end,
                    Spanned dest, int dstart, int dend) {
                if (source.length() > 0 && dest.length() == Constant.TEXT_MAX) {
                    if ((System.currentTimeMillis() - toastTime) > interval) {
                        toastTime = System.currentTimeMillis();
                        Toast
                                .makeText(KaguHomeActivity.this,
                                        R.string.edit_content_limit,
                                        Toast.LENGTH_SHORT).show();
                    }
                }
                if (dest.toString().equals(
                        getResources().getString(R.string.input_default_txt))) {
                    Bundle data = new Bundle();
                    data.putCharSequence("source", source);
                    Message message = textHandler.obtainMessage();
                    message.setData(data);
                    message.sendToTarget();
                }

                return super.filter(source, start, end, dest, dstart, dend);
            }
        };
        editText.setFilters(filters);
private Handler textHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {

            Bundle data = msg.getData();
            CharSequence source = data.getCharSequence("source");
            editText.setTextColor(Color.BLACK);
            editText.setText(source);
            editText.setSelection(source.length());
        }
    };
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