有没有办法在Android中为EditText定义最小值和最大值？

Question

我想定义一个最小值和最大值EditText.

例如:如果任何人试图在其中输入月份值,则该值必须介于1-12之间.

我可以通过使用来实现,TextWatcher但我想知道在布局文件或其他地方是否有其他方法可以做到这一点.

编辑:我不想限制字符数.我想限制价值.例如,如果我EditText在输入12时限制月份w字符,它将接受它,但如果我输入22,则在我进入时不得接受它.

Answer 1

先做这个课:

package com.test;

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

public class InputFilterMinMax implements InputFilter {

    private int min, max;

    public InputFilterMinMax(int min, int max) {
        this.min = min;
        this.max = max;
    }

    public InputFilterMinMax(String min, String max) {
        this.min = Integer.parseInt(min);
        this.max = Integer.parseInt(max);
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {   
        try {
            int input = Integer.parseInt(dest.toString() + source.toString());
            if (isInRange(min, max, input))
                return null;
        } catch (NumberFormatException nfe) { }     
        return "";
    }

    private boolean isInRange(int a, int b, int c) {
        return b > a ? c >= a && c <= b : c >= b && c <= a;
    }
}

然后在您的Activity中使用它:

EditText et = (EditText) findViewById(R.id.myEditText);
et.setFilters(new InputFilter[]{ new InputFilterMinMax("1", "12")});

这将允许用户仅输入1到12之间的值.

编辑:

使用设置您的edittext android:inputType="number".

谢谢.

Answer 2

Pratik的代码中有一个小错误.例如,如果值为10并且您在开头添加1以生成110,则过滤器函数会将新值视为101.

请参阅下面的解决方案:

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    try {
        // Remove the string out of destination that is to be replaced
        String newVal = dest.toString().substring(0, dstart) + dest.toString().substring(dend, dest.toString().length());
        // Add the new string in
        newVal = newVal.substring(0, dstart) + source.toString() + newVal.substring(dstart, newVal.length());
        int input = Integer.parseInt(newVal);
        if (isInRange(min, max, input))
            return null;
    } catch (NumberFormatException nfe) { }
    return "";
}

Answer 3

我所看到的@ Patrik的解决方案和@Zac的补充,提供的代码仍有一个大问题:

如果min==3那么就不可能输入以1或2开头的任何数字(例如:15,23)
如果min>=10那么就不可能输入任何数字,因为每个数字必须以1,2,3开头...

在我的理解中,我们无法EditText通过简单使用类来实现最小值的限制InputFilterMinMax,至少不能达到最小值,因为当用户键入正数时,值会增加,我们可以轻松地执行即时测试,以检查它是否达到限制或超出范围并阻止不符合条目.测试最小值是一个不同的故事,因为我们无法确定用户是否已完成输入,因此无法决定是否应该阻止.

这不是OP所要求的,但为了验证的目的,我已经在我的解决方案中结合InputFilter测试最大值,OnFocusChangeListener当EditText失去焦点时重新测试最小值,假设用户已完成输入并且它是这样的:

package test;


import android.text.InputFilter;

import android.text.Spanned;

public class InputFilterMax implements InputFilter {

private int max;

public InputFilterMax(int max) {
    this.max = max;
}

public InputFilterMax(String max) {
    this.max = Integer.parseInt(max);
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {   
    try {
        String replacement = source.subSequence(start, end).toString(); 

        String newVal = dest.toString().substring(0, dstart) + replacement +dest.toString().substring(dend, dest.toString().length());

        int input = Integer.parseInt(newVal);

        if (input<=max)
            return null;
    } catch (NumberFormatException nfe) { }   
//Maybe notify user that the value is not good      
return "";
}
}

和 OnFocusChangeListenerMin

package test;

import android.text.TextUtils;
import android.view.View;
import android.view.View.OnFocusChangeListener;

public class OnFocusChangeListenerMin implements OnFocusChangeListener {

private int min;

public OnFocusChangeListenerMin(int min) {
    this.min = min;
}

public OnFocusChangeListenerMin(String min) {
    this.min = Integer.parseInt(min);
}


@Override
public void onFocusChange(View v, boolean hasFocus) {
    if(!hasFocus) {
        String val = ((EditText)v).getText().toString();
        if(!TextUtils.isEmpty(val)){
            if(Integer.valueOf(val)<min){
                //Notify user that the value is not good
            }

        }
    }
}
}

然后,在活动设置InputFilterMax和OnFocusChangeListenerMin对EditText 注:您可以2都最小和最大的onFocusChangeListener.

mQteEditText.setOnFocusChangeListener( new OnFocusChangeListenerMin('20');
mQteEditText.setFilters(new InputFilter[]{new InputFilterMax(getActivity(),'50')});

Answer 4

延伸Pratik和Zac的答案.Zac在他的回答中修复了一个Pratik的小虫子.但我记得代码不支持负值,它会抛出NumberFormatException.要解决此问题,并允许MIN为负数,请使用以下代码.

在另外两行之间添加此行(以粗体显示):

newVal = newVal.substring(0,dstart)+ source.toString()+ newVal.substring(dstart,newVal.length());

if(newVal.equalsIgnoreCase(" - ")&& min <0)返回null;

int input = Integer.parseInt(newVal);

public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    try {
        // Remove the string out of destination that is to be replaced
        String newVal = dest.toString().substring(0, dstart) + dest.toString().substring(dend, dest.toString().length());
        // Add the new string in
        newVal = newVal.substring(0, dstart) + source.toString() + newVal.substring(dstart, newVal.length());
        //****Add this line (below) to allow Negative values***// 
        if(newVal.equalsIgnoreCase("-") && min < 0)return null;
        int input = Integer.parseInt(newVal);
        if (isInRange(min, max, input))
            return null;
    } catch (NumberFormatException nfe) {
        nfe.printStackTrace();
    }
    return "";
}

Answer 5

如果有人需要 Kotlin（使用实用程序）

class InputFilterMinMax: InputFilter {
    private var min:Int = 0
    private var max:Int = 0
    constructor(min:Int, max:Int) {
        this.min = min
        this.max = max
    }
    constructor(min:String, max:String) {
        this.min = Integer.parseInt(min)
        this.max = Integer.parseInt(max)
    }
    override fun filter(source:CharSequence, start:Int, end:Int, dest: Spanned, dstart:Int, dend:Int): CharSequence? {
        try
        {
            val input = Integer.parseInt(dest.toString() + source.toString())
            if (isInRange(min, max, input))
                return null
        }
        catch (nfe:NumberFormatException) {}
        return ""
    }
    private fun isInRange(a:Int, b:Int, c:Int):Boolean {
        return if (b > a) c in a..b else c in b..a
    }
}

然后从您的 Kotlin 课程中使用它

percentage_edit_text.filters = arrayOf(Utilities.InputFilterMinMax(1, 100))

此 EditText 允许 1 到 100。

然后从您的 XML 中使用它

android:inputType="number"

Answer 6

我将@Pratik Sharmas代码扩展为使用BigDecimal对象而不是整数,以便它可以接受更大的数字,并且可以解释EditText中不是数字的任何格式(如货币格式,即空格,逗号和句点)

编辑:请注意,此实现有2作为BigDecimal上设置的最小有效数字(请参阅MIN_SIG_FIG常量),因为我将其用作货币,因此小数点前总是有2个前导数字.根据您自己的实现需要更改MIN_SIG_FIG常量.

public class InputFilterMinMax implements InputFilter {
private static final int MIN_SIG_FIG = 2;
private BigDecimal min, max;

public InputFilterMinMax(BigDecimal min, BigDecimal max) {
    this.min = min;
    this.max = max;
}

public InputFilterMinMax(String min, String max) {
    this.min = new BigDecimal(min);
    this.max = new BigDecimal(max);
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart,
        int dend) {
    try {
        BigDecimal input = formatStringToBigDecimal(dest.toString()
                + source.toString());

        if (isInRange(min, max, input)) {

            return null;
        }
    } catch (NumberFormatException nfe) {

    }
    return "";
}

private boolean isInRange(BigDecimal a, BigDecimal b, BigDecimal c) {
    return b.compareTo(a) > 0 ? c.compareTo(a) >= 0 && c.compareTo(b) <= 0
            : c.compareTo(b) >= 0 && c.compareTo(a) <= 0;
}

public static BigDecimal formatStringToBigDecimal(String n) {

    Number number = null;
    try {
        number = getDefaultNumberFormat().parse(n.replaceAll("[^\\d]", ""));

        BigDecimal parsed = new BigDecimal(number.doubleValue()).divide(new BigDecimal(100), 2,
                BigDecimal.ROUND_UNNECESSARY);
        return parsed;
    } catch (ParseException e) {
        return new BigDecimal(0);
    }
}

private static NumberFormat getDefaultNumberFormat() {
    NumberFormat nf = NumberFormat.getInstance(Locale.getDefault());
    nf.setMinimumFractionDigits(MIN_SIG_FIG);
    return nf;
}

Answer 7

如果您需要带负数的范围,如-90:90,则可以使用此解决方案.

public class InputFilterMinMax implements InputFilter {

private int min, max;

public InputFilterMinMax(int min, int max) {
    this.min = min;
    this.max = max;
}

public InputFilterMinMax(String min, String max) {
    this.min = Integer.parseInt(min);
    this.max = Integer.parseInt(max);
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    try {
        String stringInput = dest.toString() + source.toString();
        int value;
        if (stringInput.length() == 1 && stringInput.charAt(0) == '-') {
            value = -1;
        } else {
            value = Integer.parseInt(stringInput);
        }
        if (isInRange(min, max, value))
            return null;
    } catch (NumberFormatException nfe) {
    }
    return "";
}

private boolean isInRange(int min, int max, int value) {
    return max > min ? value >= min && value <= max : value >= max && value <= min;
}
}

Answer 8

我找到了我自己的答案。现在已经很晚了，但我想与您分享。我实现了这个接口：

import android.text.TextWatcher;


public abstract class MinMaxTextWatcher implements TextWatcher {
    int min, max;
    public MinMaxTextWatcher(int min, int max) {
        super();
        this.min = min;
        this.max = max;
    }

}

然后在您的活动中以这种方式实现它：

private void limitEditText(final EditText ed, int min, int max) {
    ed.addTextChangedListener(new MinMaxTextWatcher(min, max) {
        @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) {
            String str = s.toString();
            int n = 0;
            try {
                n = Integer.parseInt(str);
                if(n < min) {
                    ed.setText(min);
                    Toast.makeText(getApplicationContext(), "Minimum allowed is " + min, Toast.LENGTH_SHORT).show();
                }
                else if(n > max) {
                    ed.setText("" + max);
                    Toast.makeText(getApplicationContext(), "Maximum allowed is " + max, Toast.LENGTH_SHORT).show();
                }
            }
            catch(NumberFormatException nfe) {
                ed.setText("" + min);
                Toast.makeText(getApplicationContext(), "Bad format for number!" + max, Toast.LENGTH_SHORT).show();
            }
        }
    });
}

这是一个非常简单的答案，如果有更好的请告诉我。