Android中限制EditText（輸入框）文字輸入長度

開發過程經常遇到要輸入使用者名稱等類似要限制輸入字數的要求，我們可以用InputFilter來實現，

下面是繼承的InputFilter:

public class MyInputFilter implements InputFilter {   private Paint mPaint;      private int mMaxWidth;   private static final String TAG = "MyInputFilter";      private int EDIT_WIDTH = 280;      private int mPadding = 10;      public MyInputFilter(Paint paint, int maxWidth) {      if (paint != null) {         mPaint = paint;      } else {         mPaint = new Paint();         mPaint.setTextSize(30F);      }      if (maxWidth > 0) {         mMaxWidth = maxWidth - mPadding;      } else {         mMaxWidth = EDIT_WIDTH;      }   }   @Override   public CharSequence filter(CharSequence source, int start, int end,         Spanned dest, int dstart, int dend) {      float w = mPaint.measureText(dest.toString() + source.toString());      if (w > mMaxWidth) {         //TODO: remind the user not to input anymore         return "";      }      return source;   }}

這樣來使用它：

 /*    * Set edit text input max length constraint to border.    */   public static void setEditTextFilter(EditText edit) {           int width = edit.getWidth();           Utils.log("Uitls", "edit width = " + width);               Paint paint = new Paint();      paint.setTextSize(edit.getTextSize());           InputFilter[] filters = { new MyInputFilter(paint, width) };           edit.setFilters(filters);   }

用這樣方法的優點是可以用在多個輸入框中，可是有個缺點是當用Word Flow法一次輸入較長的中文詞語或英文單詞後，不會自動截斷詞語或單詞。

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