限制Android EditText中的小数位数

我正在尝试编写一个可帮助您管理财务的应用程序。我正在使用一个EditText字段，用户可以在其中指定金额。

我将设置inputType为numberDecimal可以正常使用，除了可以让人们输入数字（例如，123.122这对金钱而言并不理想）之外，还可以。

有没有办法将小数点后的字符数限制为两个？

更优雅的方式是使用正则表达式（regex），如下所示：

public class DecimalDigitsInputFilter implements InputFilter {

Pattern mPattern;

public DecimalDigitsInputFilter(int digitsBeforeZero,int digitsAfterZero) {
    mPattern=Pattern.compile("[0-9]{0," + (digitsBeforeZero-1) + "}+((\\.[0-9]{0," + (digitsAfterZero-1) + "})?)||(\\.)?");
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {

        Matcher matcher=mPattern.matcher(dest);       
        if(!matcher.matches())
            return "";
        return null;
    }

}

要使用它，请执行以下操作：

editText.setFilters(new InputFilter[] {new DecimalDigitsInputFilter(5,2)});

不使用正则表达式的简单解决方案：

import android.text.InputFilter;
import android.text.Spanned;

/**
 * Input filter that limits the number of decimal digits that are allowed to be
 * entered.
 */
public class DecimalDigitsInputFilter implements InputFilter {

  private final int decimalDigits;

  /**
   * Constructor.
   * 
   * @param decimalDigits maximum decimal digits
   */
  public DecimalDigitsInputFilter(int decimalDigits) {
    this.decimalDigits = decimalDigits;
  }

  @Override
  public CharSequence filter(CharSequence source,
      int start,
      int end,
      Spanned dest,
      int dstart,
      int dend) {


    int dotPos = -1;
    int len = dest.length();
    for (int i = 0; i < len; i++) {
      char c = dest.charAt(i);
      if (c == '.' || c == ',') {
        dotPos = i;
        break;
      }
    }
    if (dotPos >= 0) {

      // protects against many dots
      if (source.equals(".") || source.equals(","))
      {
          return "";
      }
      // if the text is entered before the dot
      if (dend <= dotPos) {
        return null;
      }
      if (len - dotPos > decimalDigits) {
        return "";
      }
    }

    return null;
  }

}

使用方法：

editText.setFilters(new InputFilter[] {new DecimalDigitsInputFilter(2)});

此实现InputFilter解决了问题。

import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.method.DigitsKeyListener;

public class MoneyValueFilter extends DigitsKeyListener {
    public MoneyValueFilter() {
        super(false, true);
    }

    private int digits = 2;

    public void setDigits(int d) {
        digits = d;
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end,
            Spanned dest, int dstart, int dend) {
        CharSequence out = super.filter(source, start, end, dest, dstart, dend);

        // if changed, replace the source
        if (out != null) {
            source = out;
            start = 0;
            end = out.length();
        }

        int len = end - start;

        // if deleting, source is empty
        // and deleting can't break anything
        if (len == 0) {
            return source;
        }

        int dlen = dest.length();

        // Find the position of the decimal .
        for (int i = 0; i < dstart; i++) {
            if (dest.charAt(i) == '.') {
                // being here means, that a number has
                // been inserted after the dot
                // check if the amount of digits is right
                return (dlen-(i+1) + len > digits) ? 
                    "" :
                    new SpannableStringBuilder(source, start, end);
            }
        }

        for (int i = start; i < end; ++i) {
            if (source.charAt(i) == '.') {
                // being here means, dot has been inserted
                // check if the amount of digits is right
                if ((dlen-dend) + (end-(i + 1)) > digits)
                    return "";
                else
                    break;  // return new SpannableStringBuilder(source, start, end);
            }
        }

        // if the dot is after the inserted part,
        // nothing can break
        return new SpannableStringBuilder(source, start, end);
    }
}

这是一个示例InputFilter，它仅允许在小数点前最多4位，在小数点后最多1位。

价值观是允许的EditText：555.2，555，0.2

价值观是的EditText块：55555.2，055.2，555.42

        InputFilter filter = new InputFilter() {
        final int maxDigitsBeforeDecimalPoint=4;
        final int maxDigitsAfterDecimalPoint=1;

        @Override
        public CharSequence filter(CharSequence source, int start, int end,
                Spanned dest, int dstart, int dend) {
                StringBuilder builder = new StringBuilder(dest);
                builder.replace(dstart, dend, source
                        .subSequence(start, end).toString());
                if (!builder.toString().matches(
                        "(([1-9]{1})([0-9]{0,"+(maxDigitsBeforeDecimalPoint-1)+"})?)?(\\.[0-9]{0,"+maxDigitsAfterDecimalPoint+"})?"

                        )) {
                    if(source.length()==0)
                        return dest.subSequence(dstart, dend);
                    return "";
                }

            return null;

        }
    };

    mEdittext.setFilters(new InputFilter[] { filter });

我对@Pinhassi解决方案进行了一些修复。它处理一些情况：

1.您可以将光标移动到任何地方

2.减号处理

3.digitsbefore = 2和digitsafter = 4，然后输入12.4545。然后，如果要删除“。”，将不允许。

public class DecimalDigitsInputFilter implements InputFilter {
    private int mDigitsBeforeZero;
    private int mDigitsAfterZero;
    private Pattern mPattern;

    private static final int DIGITS_BEFORE_ZERO_DEFAULT = 100;
    private static final int DIGITS_AFTER_ZERO_DEFAULT = 100;

    public DecimalDigitsInputFilter(Integer digitsBeforeZero, Integer digitsAfterZero) {
    this.mDigitsBeforeZero = (digitsBeforeZero != null ? digitsBeforeZero : DIGITS_BEFORE_ZERO_DEFAULT);
    this.mDigitsAfterZero = (digitsAfterZero != null ? digitsAfterZero : DIGITS_AFTER_ZERO_DEFAULT);
    mPattern = Pattern.compile("-?[0-9]{0," + (mDigitsBeforeZero) + "}+((\\.[0-9]{0," + (mDigitsAfterZero)
        + "})?)||(\\.)?");
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    String replacement = source.subSequence(start, end).toString();
    String newVal = dest.subSequence(0, dstart).toString() + replacement
        + dest.subSequence(dend, dest.length()).toString();
    Matcher matcher = mPattern.matcher(newVal);
    if (matcher.matches())
        return null;

    if (TextUtils.isEmpty(source))
        return dest.subSequence(dstart, dend);
    else
        return "";
    }
}

我不喜欢其他解决方案，而是创建了自己的解决方案。使用此解决方案，您不能在该点之前输入超过MAX_BEFORE_POINT位，而小数位数不能超过MAX_DECIMAL。

您只是不能输入过多的数字，没有其他效果！另外，如果您输入“。” 它输入“ 0”。

1. 在布局中将EditText设置为：

   android：inputType =“ numberDecimal”

2. 在您的onCreate中添加侦听器。如果要修改该点前后的位数，请编辑对PerfectDecimal的调用（str，NUMBER_BEFORE_POINT，NUMBER_DECIMALS），此处设置为3和2

   EditText targetEditText = (EditText)findViewById(R.id.targetEditTextLayoutId);
   
   targetEditText.addTextChangedListener(new TextWatcher() {
     public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {}
   
     public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {}
   
     public void afterTextChanged(Editable arg0) {
       String str = targetEditText.getText().toString();
       if (str.isEmpty()) return;
       String str2 = PerfectDecimal(str, 3, 2);
   
       if (!str2.equals(str)) {
           targetEditText.setText(str2);
           int pos = targetEditText.getText().length();
           targetEditText.setSelection(pos);
       }
     }
   });

3. 包括此功能：

   public String PerfectDecimal(String str, int MAX_BEFORE_POINT, int MAX_DECIMAL){
     if(str.charAt(0) == '.') str = "0"+str;
     int max = str.length();
   
     String rFinal = "";
     boolean after = false;
     int i = 0, up = 0, decimal = 0; char t;
     while(i < max){
       t = str.charAt(i);
       if(t != '.' && after == false){
           up++;
           if(up > MAX_BEFORE_POINT) return rFinal;
       }else if(t == '.'){
           after = true;
       }else{
           decimal++;
           if(decimal > MAX_DECIMAL)
               return rFinal;
       }
       rFinal = rFinal + t;
       i++;
     }return rFinal;
   }

完成了！

我通过TextWatcher以下方式在的帮助下实现了这一目标

final EditText et = (EditText) findViewById(R.id.EditText1);
int count = -1;
et.addTextChangedListener(new TextWatcher() {
    public void onTextChanged(CharSequence arg0, int arg1, int arg2,int arg3) {             

    }
    public void beforeTextChanged(CharSequence arg0, int arg1,int arg2, int arg3) {             

    }

    public void afterTextChanged(Editable arg0) {
        if (arg0.length() > 0) {
            String str = et.getText().toString();
            et.setOnKeyListener(new OnKeyListener() {
                public boolean onKey(View v, int keyCode, KeyEvent event) {
                    if (keyCode == KeyEvent.KEYCODE_DEL) {
                        count--;
                        InputFilter[] fArray = new InputFilter[1];
                        fArray[0] = new InputFilter.LengthFilter(100);
                        et.setFilters(fArray);
                        //change the edittext's maximum length to 100. 
                        //If we didn't change this the edittext's maximum length will
                        //be number of digits we previously entered.
                    }
                    return false;
                }
            });
            char t = str.charAt(arg0.length() - 1);
            if (t == '.') {
                count = 0;
            }
            if (count >= 0) {
                if (count == 2) {                        
                    InputFilter[] fArray = new InputFilter[1];
                    fArray[0] = new InputFilter.LengthFilter(arg0.length());
                    et.setFilters(fArray);
                    //prevent the edittext from accessing digits 
                    //by setting maximum length as total number of digits we typed till now.
                }
                count++;
            }
        }
    }
});

此解决方案不允许用户在小数点后输入两位以上的数字。您也可以输入小数点前的任何数字。请参阅此博客http://v4all123.blogspot.com/2013/05/set-limit-for-fraction-in-decimal.html，以为多个EditText设置过滤器。我希望这将有所帮助。谢谢。

我想到的InputFilter允许您配置小数点之前和之后的位数。此外，它不允许前导零。

public class DecimalDigitsInputFilter implements InputFilter
{
    Pattern pattern;

    public DecimalDigitsInputFilter(int digitsBeforeDecimal, int digitsAfterDecimal)
    {
        pattern = Pattern.compile("(([1-9]{1}[0-9]{0," + (digitsBeforeDecimal - 1) + "})?||[0]{1})((\\.[0-9]{0," + digitsAfterDecimal + "})?)||(\\.)?");
    }

    @Override public CharSequence filter(CharSequence source, int sourceStart, int sourceEnd, Spanned destination, int destinationStart, int destinationEnd)
    {
        // Remove the string out of destination that is to be replaced.
        String newString = destination.toString().substring(0, destinationStart) + destination.toString().substring(destinationEnd, destination.toString().length());

        // Add the new string in.
        newString = newString.substring(0, destinationStart) + source.toString() + newString.substring(destinationStart, newString.length());

        // Now check if the new string is valid.
        Matcher matcher = pattern.matcher(newString);

        if(matcher.matches())
        {
            // Returning null indicates that the input is valid.
            return null;
        }

        // Returning the empty string indicates the input is invalid.
        return "";
    }
}

// To use this InputFilter, attach it to your EditText like so:
final EditText editText = (EditText) findViewById(R.id.editText);

EditText.setFilters(new InputFilter[]{new DecimalDigitsInputFilter(4, 4)});

要求是小数点后两位。应该有任何限制为小数点前的数字。因此，解决方案应该是

public class DecimalDigitsInputFilter implements InputFilter {

    Pattern mPattern;

    public DecimalDigitsInputFilter() {
        mPattern = Pattern.compile("[0-9]*+((\\.[0-9]?)?)||(\\.)?");
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        Matcher matcher = mPattern.matcher(dest);
        if (!matcher.matches())
            return "";
        return null;
    }
}

并用作

mEditText.setFilters(new InputFilter[]{new DecimalDigitsInputFilter()});

感谢@Pinhassi的启发。

我的解决方案很简单，并且完美！

public class DecimalInputTextWatcher implements TextWatcher {

private String mPreviousValue;
private int mCursorPosition;
private boolean mRestoringPreviousValueFlag;
private int mDigitsAfterZero;
private EditText mEditText;

public DecimalInputTextWatcher(EditText editText, int digitsAfterZero) {
    mDigitsAfterZero = digitsAfterZero;
    mEditText = editText;
    mPreviousValue = "";
    mRestoringPreviousValueFlag = false;
}

@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    if (!mRestoringPreviousValueFlag) {
        mPreviousValue = s.toString();
        mCursorPosition = mEditText.getSelectionStart();
    }
}

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}

@Override
public void afterTextChanged(Editable s) {
    if (!mRestoringPreviousValueFlag) {

        if (!isValid(s.toString())) {
            mRestoringPreviousValueFlag = true;
            restorePreviousValue();
        }

    } else {
        mRestoringPreviousValueFlag = false;
    }
}

private void restorePreviousValue() {
    mEditText.setText(mPreviousValue);
    mEditText.setSelection(mCursorPosition);
}

private boolean isValid(String s) {
    Pattern patternWithDot = Pattern.compile("[0-9]*((\\.[0-9]{0," + mDigitsAfterZero + "})?)||(\\.)?");
    Pattern patternWithComma = Pattern.compile("[0-9]*((,[0-9]{0," + mDigitsAfterZero + "})?)||(,)?");

    Matcher matcherDot = patternWithDot.matcher(s);
    Matcher matcherComa = patternWithComma.matcher(s);

    return matcherDot.matches() || matcherComa.matches();
}
}

用法：

myTextEdit.addTextChangedListener(new DecimalInputTextWatcher(myTextEdit, 2));

在将字符串放入TextView之前，请尝试使用NumberFormat.getCurrencyInstance（）格式化字符串。

就像是：

NumberFormat currency = NumberFormat.getCurrencyInstance();
myTextView.setText(currency.format(dollars));

编辑 -我在文档中找不到货币的inputType。我想这是因为有些货币对日元的小数位不遵循相同的规则，例如日元。

如LeffelMania所述，您可以使用上面的代码并在TextWatcher上设置来更正用户输入EditText。

@Pinhassi解决方案略有改进。

效果很好。它验证串联的字符串。

public class DecimalDigitsInputFilter implements InputFilter {

Pattern mPattern;

public DecimalDigitsInputFilter() {
    mPattern = Pattern.compile("([1-9]{1}[0-9]{0,2}([0-9]{3})*(\\.[0-9]{0,2})?|[1-9]{1}[0-9]{0,}(\\.[0-9]{0,2})?|0(\\.[0-9]{0,2})?|(\\.[0-9]{1,2})?)");

}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {

    String formatedSource = source.subSequence(start, end).toString();

    String destPrefix = dest.subSequence(0, dstart).toString();

    String destSuffix = dest.subSequence(dend, dest.length()).toString();

    String result = destPrefix + formatedSource + destSuffix;

    result = result.replace(",", ".");

    Matcher matcher = mPattern.matcher(result);

    if (matcher.matches()) {
        return null;
    }

    return "";
}

 }

我已经修改了上述解决方案，并创建了以下解决方案。您可以设置小数点前后的位数。

public class DecimalDigitsInputFilter implements InputFilter {

private final Pattern mPattern;

public DecimalDigitsInputFilter(int digitsBeforeZero, int digitsAfterZero) {
    mPattern = Pattern.compile(String.format("[0-9]{0,%d}(\\.[0-9]{0,%d})?", digitsBeforeZero, digitsAfterZero));
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    Matcher matcher = mPattern.matcher(createResultString(source, start, end, dest, dstart, dend));
    if (!matcher.matches())
        return "";
    return null;
}

private String createResultString(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    String sourceString = source.toString();
    String destString = dest.toString();
    return destString.substring(0, dstart) + sourceString.substring(start, end) + destString.substring(dend);
}

}

DecimalFormat form = new DecimalFormat("#.##", new DecimalFormatSymbols(Locale.US));
    EditText et; 
    et.setOnEditorActionListener(new TextView.OnEditorActionListener() {
        @Override
        public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {

        if (actionId == EditorInfo.IME_ACTION_DONE) {
            double a = Double.parseDouble(et.getText().toString());
            et.setText(form.format(a));
        }
        return false;
    }
});

这是在退出编辑阶段时将字段格式化为正确的格式。在那时，它只有2个小数字符。我认为这是很简单的方法。

我试图使其变得更简单，这里的所有答案都非常复杂。查看我的代码并自己决定-

int temp  = 0;
int check = 0;

editText.addTextChangedListener(new TextWatcher() {

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

        if(editText.getText().toString().length()<temp)
        {
            if(!editText.getText().toString().contains("."))
                editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()-1) });
            else
                editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+1) });

        }

        if(!editText.getText().toString().contains("."))
        {
            editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+1) });
            check=0;
        }


        else if(check==0)
        {
            check=1;
            editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+2) });
        }
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
        temp = editText.getText().toString().length();


    }

    @Override
    public void afterTextChanged(Editable s) {
        // TODO Auto-generated method stub

    }
});

我真的很喜欢Pinhassi的答案，但是注意到在用户在小数点后输入指定的数字后，您将无法再在小数点的左侧输入文本。问题在于该解决方案仅测试了之前输入的文本，而不测试了当前输入的文本。因此，这是我的解决方案，将新字符插入原始文本以进行验证。

package com.test.test;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.text.InputFilter;
import android.text.Spanned;
import android.util.Log;

public class InputFilterCurrency implements InputFilter {
    Pattern moPattern;

    public InputFilterCurrency(int aiMinorUnits) {
        // http://www.regexplanet.com/advanced/java/index.html
        moPattern=Pattern.compile("[0-9]*+((\\.[0-9]{0,"+ aiMinorUnits + "})?)||(\\.)?");

    } // InputFilterCurrency

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        String lsStart  = "";
        String lsInsert = "";
        String lsEnd    = "";
        String lsText   = "";

        Log.d("debug", moPattern.toString());
        Log.d("debug", "source: " + source + ", start: " + start + ", end:" + end + ", dest: " + dest + ", dstart: " + dstart + ", dend: " + dend );

        lsText = dest.toString();

        // If the length is greater then 0, then insert the new character
        // into the original text for validation
        if (lsText.length() > 0) {

            lsStart = lsText.substring(0, dstart);
            Log.d("debug", "lsStart : " + lsStart);
            // Check to see if they have deleted a character
            if (source != "") {
                lsInsert = source.toString();
                Log.d("debug", "lsInsert: " + lsInsert);
            } // if
            lsEnd = lsText.substring(dend);
            Log.d("debug", "lsEnd   : " + lsEnd);
            lsText = lsStart + lsInsert + lsEnd;
            Log.d("debug", "lsText  : " + lsText);

        } // if

        Matcher loMatcher = moPattern.matcher(lsText);
        Log.d("debug", "loMatcher.matches(): " + loMatcher.matches() + ", lsText: " + lsText);
        if(!loMatcher.matches()) {
            return "";
        }
        return null;

    } // CharSequence

} // InputFilterCurrency

并设置editText过滤器的调用

editText.setFilters(new InputFilter[] {new InputFilterCurrency(2)});

Ouput with two decimal places
05-22 15:25:33.434: D/debug(30524): [0-9]*+((\.[0-9]{0,2})?)||(\.)?
05-22 15:25:33.434: D/debug(30524): source: 5, start: 0, end:1, dest: 123.4, dstart: 5, dend: 5
05-22 15:25:33.434: D/debug(30524): lsStart : 123.4
05-22 15:25:33.434: D/debug(30524): lsInsert: 5
05-22 15:25:33.434: D/debug(30524): lsEnd   : 
05-22 15:25:33.434: D/debug(30524): lsText  : 123.45
05-22 15:25:33.434: D/debug(30524): loMatcher.matches(): true, lsText: 123.45

Ouput inserting a 5 in the middle
05-22 15:26:17.624: D/debug(30524): [0-9]*+((\.[0-9]{0,2})?)||(\.)?
05-22 15:26:17.624: D/debug(30524): source: 5, start: 0, end:1, dest: 123.45, dstart: 2, dend: 2
05-22 15:26:17.624: D/debug(30524): lsStart : 12
05-22 15:26:17.624: D/debug(30524): lsInsert: 5
05-22 15:26:17.624: D/debug(30524): lsEnd   : 3.45
05-22 15:26:17.624: D/debug(30524): lsText  : 1253.45
05-22 15:26:17.624: D/debug(30524): loMatcher.matches(): true, lsText: 1253.45

我改进了使用Pinhassi的正则表达式的解决方案，因此它也可以正确处理边缘情况。在检查输入是否正确之前，首先按照android docs的说明构造最终字符串。

public class DecimalDigitsInputFilter implements InputFilter {

    private Pattern mPattern;

    private static final Pattern mFormatPattern = Pattern.compile("\\d+\\.\\d+");

    public DecimalDigitsInputFilter(int digitsBeforeDecimal, int digitsAfterDecimal) {
        mPattern = Pattern.compile(
            "^\\d{0," + digitsBeforeDecimal + "}([\\.,](\\d{0," + digitsAfterDecimal +
                "})?)?$");
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, 
                               int dstart, int dend) {

        String newString =
            dest.toString().substring(0, dstart) + source.toString().substring(start, end) 
            + dest.toString().substring(dend, dest.toString().length());

        Matcher matcher = mPattern.matcher(newString);
        if (!matcher.matches()) {
            return "";
        }
        return null;
    }
}

用法：

editText.setFilters(new InputFilter[] {new DecimalDigitsInputFilter(5,2)});

此处提供了简单助手类，以防止用户在小数点后输入两位以上的数字：

public class CostFormatter  implements TextWatcher {

private final EditText costEditText;

public CostFormatter(EditText costEditText) {
    this.costEditText = costEditText;
}

@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 synchronized void afterTextChanged(final Editable text) {
    String cost = text.toString().trim();

    if(!cost.endsWith(".") && cost.contains(".")){
        String numberBeforeDecimal = cost.split("\\.")[0];
        String numberAfterDecimal = cost.split("\\.")[1];

        if(numberAfterDecimal.length() > 2){
            numberAfterDecimal = numberAfterDecimal.substring(0, 2);
        }
        cost = numberBeforeDecimal + "." + numberAfterDecimal;
    }
    costEditText.removeTextChangedListener(this);
    costEditText.setText(cost);
    costEditText.setSelection(costEditText.getText().toString().trim().length());
    costEditText.addTextChangedListener(this);
}
}

我已经更改了答案№6（由Favas Kv撰写），因为在那里您可以将指针放在第一位。

final InputFilter [] filter = { new InputFilter() {

    @Override
    public CharSequence filter(CharSequence source, int start, int end,
                               Spanned dest, int dstart, int dend) {
        StringBuilder builder = new StringBuilder(dest);
        builder.replace(dstart, dend, source
                .subSequence(start, end).toString());
        if (!builder.toString().matches(
                "(([1-9]{1})([0-9]{0,4})?(\\.)?)?([0-9]{0,2})?"

        )) {
            if(source.length()==0)
                return dest.subSequence(dstart, dend);
            return "";
        }
        return null;
    }
}};

就像其他人说的那样，我在项目中添加了此类，并将过滤器设置为所需的过滤器EditText。

过滤器是从@Pixel的答案复制而来的。我只是把它们放在一起。

public class DecimalDigitsInputFilter implements InputFilter {

    Pattern mPattern;

    public DecimalDigitsInputFilter() {
        mPattern = Pattern.compile("([1-9]{1}[0-9]{0,2}([0-9]{3})*(\\.[0-9]{0,2})?|[1-9]{1}[0-9]{0,}(\\.[0-9]{0,2})?|0(\\.[0-9]{0,2})?|(\\.[0-9]{1,2})?)");

    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {

        String formatedSource = source.subSequence(start, end).toString();

        String destPrefix = dest.subSequence(0, dstart).toString();

        String destSuffix = dest.subSequence(dend, dest.length()).toString();

        String result = destPrefix + formatedSource + destSuffix;

        result = result.replace(",", ".");

        Matcher matcher = mPattern.matcher(result);

        if (matcher.matches()) {
            return null;
        }

        return "";
    }
}

现在这样设置过滤器EditText。

mEditText.setFilters(new InputFilter[]{new DecimalDigitsInputFilter()});

这里一件重要的事情是它确实解决了我的问题，即不允许在小数点后显示两位以上的数字，EditText但是问题是当我getText()从那开始时EditText，它返回我键入的整个输入。

例如，在上应用过滤器后EditText，我尝试设置输入1.5699856987。因此，在屏幕上显示1.56是完美的。

然后，我想将此输入用于其他一些计算，所以我想从该输入字段（EditText）中获取文本。当我打电话时，mEditText.getText().toString()它返回1.5699856987，这在我的情况下是不可接受的。

因此，我必须在从中获取值后再次解析该值EditText。

BigDecimal amount = new BigDecimal(Double.parseDouble(mEditText.getText().toString().trim()))
    .setScale(2, RoundingMode.HALF_UP);

setScale从中获取全文后，在这里做了把戏EditText。

我也遇到了这个问题。我希望能够在许多EditText中重用代码。这是我的解决方案：

用法：

CurrencyFormat watcher = new CurrencyFormat();
priceEditText.addTextChangedListener(watcher);

类：

public static class CurrencyFormat implements TextWatcher {

    public void onTextChanged(CharSequence arg0, int start, int arg2,int arg3) {}

    public void beforeTextChanged(CharSequence arg0, int start,int arg2, int arg3) {}

    public void afterTextChanged(Editable arg0) {
        int length = arg0.length();
        if(length>0){
            if(nrOfDecimal(arg0.toString())>2)
                    arg0.delete(length-1, length);
        }

    }


    private int nrOfDecimal(String nr){
        int len = nr.length();
        int pos = len;
        for(int i=0 ; i<len; i++){
            if(nr.charAt(i)=='.'){
                pos=i+1;
                    break;
            }
        }
        return len-pos;
    }
}

@Meh for ..

txtlist.setFilters(new InputFilter[] { new DigitsKeyListener( Boolean.FALSE,Boolean.TRUE) {

        int beforeDecimal = 7;
        int afterDecimal = 2;

        @Override
        public CharSequence filter(CharSequence source, int start, int end,Spanned dest, int dstart, int dend) {

            String etText = txtlist.getText().toString();
            String temp = txtlist.getText() + source.toString();
            if (temp.equals(".")) {
                return "0.";
            } else if (temp.toString().indexOf(".") == -1) {
                // no decimal point placed yet
                 if (temp.length() > beforeDecimal) {
                    return "";
                }
            } else {
                int dotPosition ;
                int cursorPositon = txtlistprice.getSelectionStart();
                if (etText.indexOf(".") == -1) {
                    dotPosition = temp.indexOf(".");
                }else{
                    dotPosition = etText.indexOf(".");
                }
                if(cursorPositon <= dotPosition){
                    String beforeDot = etText.substring(0, dotPosition);
                    if(beforeDot.length()<beforeDecimal){
                        return source;
                    }else{
                        if(source.toString().equalsIgnoreCase(".")){
                            return source;
                        }else{
                            return "";
                        }
                    }
                }else{
                    temp = temp.substring(temp.indexOf(".") + 1);
                    if (temp.length() > afterDecimal) {
                        return "";
                    }
                }
            }
            return super.filter(source, start, end, dest, dstart, dend);
        }
    } });

一个很晚的回应：我们可以这样简单地做到：

etv.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) {
            if (s.toString().length() > 3 && s.toString().contains(".")) {
                if (s.toString().length() - s.toString().indexOf(".") > 3) {
                    etv.setText(s.toString().substring(0, s.length() - 1));
                    etv.setSelection(edtSendMoney.getText().length());
                }
            }
        }

        @Override
        public void afterTextChanged(Editable arg0) {
        }
}

这是小数点后TextWatcher仅允许n个数字的位置。

TextWatcher

private static boolean flag;
public static TextWatcher getTextWatcherAllowAfterDeci(final int allowAfterDecimal){

    TextWatcher watcher = 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
            String str = s.toString();
            int index = str.indexOf ( "." );
            if(index>=0){
                if((index+1)<str.length()){
                    String numberD = str.substring(index+1);
                    if (numberD.length()!=allowAfterDecimal) {
                        flag=true;
                    }else{
                        flag=false;
                    }   
                }else{
                    flag = false;
                }                   
            }else{
                flag=false;
            }
            if(flag)
                s.delete(s.length() - 1,
                        s.length());
        }
    };
    return watcher;
}

如何使用

yourEditText.addTextChangedListener(getTextWatcherAllowAfterDeci(1));

最简单的方法是：

et.addTextChangedListener(new TextWatcher() {
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
        String text = arg0.toString();
        if (text.contains(".") && text.substring(text.indexOf(".") + 1).length() > 2) {
            et.setText(text.substring(0, text.length() - 1));
            et.setSelection(et.getText().length());
        }
    }

    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {

    }

    public void afterTextChanged(Editable arg0) {
    }
});

这是我的解决方案：

     yourEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            NumberFormat formatter = new DecimalFormat("#.##");
            double doubleVal = Double.parseDouble(s.toString());
            yourEditText.setText(formatter.format(doubleVal));
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,int after) {}

        @Override
        public void afterTextChanged(Editable s) {}
    });

如果用户输入的数字在小数点后有两个以上的数字，它将被自动更正。

希望我有所帮助！

这对我来说很好。即使更改焦点并取回后，也可以输入值。例如：123.00， 12.12，0.01等。

1. Integer.parseInt(getString(R.string.valuelength)) 指定digits.Values从string.xml文件访问的输入的长度。更改值非常安静。2. Integer.parseInt(getString(R.string.valuedecimal))，这是小数位数最大限制。

private InputFilter[] valDecimalPlaces;
private ArrayList<EditText> edittextArray;

valDecimalPlaces = new InputFilter[] { new DecimalDigitsInputFilterNew(
    Integer.parseInt(getString(R.string.valuelength)),
    Integer.parseInt(getString(R.string.valuedecimal))) 
};

EditText允许执行操作的值数组。

for (EditText etDecimalPlace : edittextArray) {
            etDecimalPlace.setFilters(valDecimalPlaces);

我只使用了包含多个edittext Next DecimalDigitsInputFilterNew.class文件的值数组。

import android.text.InputFilter;
import android.text.Spanned;

public class DecimalDigitsInputFilterNew implements InputFilter {

    private final int decimalDigits;
    private final int before;

    public DecimalDigitsInputFilterNew(int before ,int decimalDigits) {
        this.decimalDigits = decimalDigits;
        this.before = before;
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end,
        Spanned dest, int dstart, int dend) {
        StringBuilder builder = new StringBuilder(dest);
        builder.replace(dstart, dend, source
              .subSequence(start, end).toString());
        if (!builder.toString().matches("(([0-9]{1})([0-9]{0,"+(before-1)+"})?)?(\\.[0-9]{0,"+decimalDigits+"})?")) {
             if(source.length()==0)
                  return dest.subSequence(dstart, dend);
             return "";
        }
        return null;
    }
}

这是建立在pinhassi的答案之上的-我遇到的问题是，一旦达到十进制限制，您就无法在十进制之前添加值。要解决此问题，我们需要在进行模式匹配之前构造最终的字符串。

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.text.InputFilter;
import android.text.Spanned;

public class DecimalLimiter implements InputFilter
{
    Pattern mPattern;

    public DecimalLimiter(int digitsBeforeZero,int digitsAfterZero) 
    {
        mPattern=Pattern.compile("[0-9]{0," + (digitsBeforeZero) + "}+((\\.[0-9]{0," + (digitsAfterZero) + "})?)||(\\.)?");
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) 
    {
        StringBuilder sb = new StringBuilder(dest);
        sb.insert(dstart, source, start, end);

        Matcher matcher = mPattern.matcher(sb.toString());
        if(!matcher.matches())
            return "";
        return null;
    }
}

et = (EditText) vw.findViewById(R.id.tx_edittext);

et.setFilters(new InputFilter[] {
        new DigitsKeyListener(Boolean.FALSE, Boolean.TRUE) {
            int beforeDecimal = 5, afterDecimal = 2;

            @Override
            public CharSequence filter(CharSequence source, int start, int end,
                    Spanned dest, int dstart, int dend) {
                String temp = et.getText() + source.toString();

                if (temp.equals(".")) {
                    return "0.";
                }
                else if (temp.toString().indexOf(".") == -1) {
                    // no decimal point placed yet
                    if (temp.length() > beforeDecimal) {
                        return "";
                    }
                } else {
                    temp = temp.substring(temp.indexOf(".") + 1);
                    if (temp.length() > afterDecimal) {
                        return "";
                    }
                }

                return super.filter(source, start, end, dest, dstart, dend);
            }
        }
});