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Android 中限制 EditText 文本长度的最佳方法是什么

发布于 2024-09-10 20:48:54 字数 84 浏览 5 评论 0原文

在 Android 中限制 EditText 文本长度的最佳方法是什么？

有没有办法通过 xml 来做到这一点？

原文

What's the best way to limit the text length of an EditText in Android?

Is there a way to do this via xml?

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评论（22）

小嗷兮 2024-09-17 20:48:55

我遇到了这个问题，我认为我们缺少一种解释清楚的方法来以编程方式执行此操作，而不会丢失已设置的过滤器。

在 XML 中设置长度：

正如接受的答案正确指出的那样，如果您想为 EditText 定义一个固定长度，并且以后不再更改，只需在您的 EditText XML 中定义：

android:maxLength="10"

以编程方式设置长度

要以编程方式设置长度，您需要通过InputFilter 进行设置。但是，如果您创建一个新的InputFilter 并将其设置为EditText，您将丢失所有其他已定义的过滤器（例如maxLines、inputType 等），您可能已通过XML 或以编程方式添加了这些过滤器。

所以这是错误：

editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});

为了避免丢失以前添加的过滤器，您需要获取这些过滤器，添加新过滤器（在本例中为 maxLength），然后将过滤器设置回 EditText 如下：

Java

InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength); 
editText.setFilters(newFilters);

Kotlin 然而，这对每个人来说都更容易，您还需要将过滤器添加到现有的过滤器中，但您可以通过简单的方法来实现：

editText.filters += InputFilter.LengthFilter(maxLength)

I have had this problem and I consider we are missing a well explained way of doing this programmatically without losing the already set filters.

Setting the length in XML:

As the accepted answer states correctly, if you want to define a fixed length to an EditText which you won't change further in the future just define in your EditText XML:

android:maxLength="10"

Setting the length programmatically

To set the length programmatically you'll need to set it through an InputFilter. But if you create a new InputFilter and set it to the EditText you will lose all the other already defined filters (e.g. maxLines, inputType, etc) which you might have added either through XML or programatically.

So this is WRONG:

editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});

To avoid losing previously added filters you need to get those filters, add the new one (maxLength in this case), and set the filters back to the EditText as follow:

Java

InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength); 
editText.setFilters(newFilters);

Kotlin however made it easier for everyone, you also need to add the filter to the already existing ones but you can achieve that with a simple:

editText.filters += InputFilter.LengthFilter(maxLength)
回复 原文
初雪 2024-09-17 20:48:55

对于已经使用自定义输入过滤器并且想要限制最大长度的用户请注意：

当您在代码中分配输入过滤器时，所有先前设置的输入过滤器都将被清除，包括一组带有 的输入过滤器android:maxLength。当我尝试使用自定义输入过滤器来防止使用密码字段中不允许的某些字符时，我发现了这一点。使用 setFilters 设置该过滤器后，不再观察到 maxLength。解决方案是以编程方式将 maxLength 和我的自定义过滤器设置在一起。像这样的事情：

myEditText.setFilters(new InputFilter[] {
        new PasswordCharFilter(), new InputFilter.LengthFilter(20)
});

A note to people who are already using a custom input filter and also want to limit the max length:

When you assign input filters in code all previously set input filters are cleared, including one set with android:maxLength. I found this out when attempting to use a custom input filter to prevent the use of some characters that we don't allow in a password field. After setting that filter with setFilters the maxLength was no longer observed. The solution was to set maxLength and my custom filter together programmatically. Something like this:

myEditText.setFilters(new InputFilter[] {
        new PasswordCharFilter(), new InputFilter.LengthFilter(20)
});
回复 原文
毁梦 2024-09-17 20:48:55
TextView tv = new TextView(this);
tv.setFilters(new InputFilter[]{ new InputFilter.LengthFilter(250) });

TextView tv = new TextView(this);
tv.setFilters(new InputFilter[]{ new InputFilter.LengthFilter(250) });
回复 原文
小忆控 2024-09-17 20:48:55

对于其他想知道如何实现此目的的人，这里是我的扩展 EditText 类 EditTextNumeric。

.setMaxLength(int) - 设置最大位数

.setMaxValue(int) - 限制最大整数值

.setMin(int) - 限制最小值整数值

.getValue() - 获取整数值

import android.content.Context;
import android.text.InputFilter;
import android.text.InputType;
import android.widget.EditText;

public class EditTextNumeric extends EditText {
    protected int max_value = Integer.MAX_VALUE;
    protected int min_value = Integer.MIN_VALUE;

    // constructor
    public EditTextNumeric(Context context) {
        super(context);
        this.setInputType(InputType.TYPE_CLASS_NUMBER);
    }

    // checks whether the limits are set and corrects them if not within limits
    @Override
    protected void onTextChanged(CharSequence text, int start, int before, int after) {
        if (max_value != Integer.MAX_VALUE) {
            try {
                if (Integer.parseInt(this.getText().toString()) > max_value) {
                    // change value and keep cursor position
                    int selection = this.getSelectionStart();
                    this.setText(String.valueOf(max_value));
                    if (selection >= this.getText().toString().length()) {
                        selection = this.getText().toString().length();
                    }
                    this.setSelection(selection);
                }
            } catch (NumberFormatException exception) {
                super.onTextChanged(text, start, before, after);
            }
        }
        if (min_value != Integer.MIN_VALUE) {
            try {
                if (Integer.parseInt(this.getText().toString()) < min_value) {
                    // change value and keep cursor position
                    int selection = this.getSelectionStart();
                    this.setText(String.valueOf(min_value));
                    if (selection >= this.getText().toString().length()) {
                        selection = this.getText().toString().length();
                    }
                    this.setSelection(selection);
                }
            } catch (NumberFormatException exception) {
                super.onTextChanged(text, start, before, after);
            }
        }
        super.onTextChanged(text, start, before, after);
    }

    // set the max number of digits the user can enter
    public void setMaxLength(int length) {
        InputFilter[] FilterArray = new InputFilter[1];
        FilterArray[0] = new InputFilter.LengthFilter(length);
        this.setFilters(FilterArray);
    }

    // set the maximum integer value the user can enter.
    // if exeeded, input value will become equal to the set limit
    public void setMaxValue(int value) {
        max_value = value;
    }
    // set the minimum integer value the user can enter.
    // if entered value is inferior, input value will become equal to the set limit
    public void setMinValue(int value) {
        min_value = value;
    }

    // returns integer value or 0 if errorous value
    public int getValue() {
        try {
            return Integer.parseInt(this.getText().toString());
        } catch (NumberFormatException exception) {
            return 0;
        }
    }
}

用法示例：

final EditTextNumeric input = new EditTextNumeric(this);
input.setMaxLength(5);
input.setMaxValue(total_pages);
input.setMinValue(1);

适用于 EditText 的所有其他方法和属性当然也可以工作。

For anyone else wondering how to achieve this, here is my extended EditText class EditTextNumeric.

.setMaxLength(int) - sets maximum number of digits

.setMaxValue(int) - limit maximum integer value

.setMin(int) - limit minimum integer value

.getValue() - get integer value

import android.content.Context;
import android.text.InputFilter;
import android.text.InputType;
import android.widget.EditText;

public class EditTextNumeric extends EditText {
    protected int max_value = Integer.MAX_VALUE;
    protected int min_value = Integer.MIN_VALUE;

    // constructor
    public EditTextNumeric(Context context) {
        super(context);
        this.setInputType(InputType.TYPE_CLASS_NUMBER);
    }

    // checks whether the limits are set and corrects them if not within limits
    @Override
    protected void onTextChanged(CharSequence text, int start, int before, int after) {
        if (max_value != Integer.MAX_VALUE) {
            try {
                if (Integer.parseInt(this.getText().toString()) > max_value) {
                    // change value and keep cursor position
                    int selection = this.getSelectionStart();
                    this.setText(String.valueOf(max_value));
                    if (selection >= this.getText().toString().length()) {
                        selection = this.getText().toString().length();
                    }
                    this.setSelection(selection);
                }
            } catch (NumberFormatException exception) {
                super.onTextChanged(text, start, before, after);
            }
        }
        if (min_value != Integer.MIN_VALUE) {
            try {
                if (Integer.parseInt(this.getText().toString()) < min_value) {
                    // change value and keep cursor position
                    int selection = this.getSelectionStart();
                    this.setText(String.valueOf(min_value));
                    if (selection >= this.getText().toString().length()) {
                        selection = this.getText().toString().length();
                    }
                    this.setSelection(selection);
                }
            } catch (NumberFormatException exception) {
                super.onTextChanged(text, start, before, after);
            }
        }
        super.onTextChanged(text, start, before, after);
    }

    // set the max number of digits the user can enter
    public void setMaxLength(int length) {
        InputFilter[] FilterArray = new InputFilter[1];
        FilterArray[0] = new InputFilter.LengthFilter(length);
        this.setFilters(FilterArray);
    }

    // set the maximum integer value the user can enter.
    // if exeeded, input value will become equal to the set limit
    public void setMaxValue(int value) {
        max_value = value;
    }
    // set the minimum integer value the user can enter.
    // if entered value is inferior, input value will become equal to the set limit
    public void setMinValue(int value) {
        min_value = value;
    }

    // returns integer value or 0 if errorous value
    public int getValue() {
        try {
            return Integer.parseInt(this.getText().toString());
        } catch (NumberFormatException exception) {
            return 0;
        }
    }
}

Example usage:

final EditTextNumeric input = new EditTextNumeric(this);
input.setMaxLength(5);
input.setMaxValue(total_pages);
input.setMinValue(1);

All other methods and attributes that apply to EditText, of course work too.

回复 原文
謸气贵蔟 2024-09-17 20:48:55

Xml

android:maxLength="10"

Java：

InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength);
editText.setFilters(newFilters);

Kotlin：

editText.filters += InputFilter.LengthFilter(maxLength)

Xml

android:maxLength="10"

Java:

InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength);
editText.setFilters(newFilters);

Kotlin:

editText.filters += InputFilter.LengthFilter(maxLength)
回复 原文
贱贱哒 2024-09-17 20:48:55

根据 goto10 的观察，我将以下代码放在一起，以防止通过设置最大长度丢失其他过滤器：

/**
 * This sets the maximum length in characters of an EditText view. Since the
 * max length must be done with a filter, this method gets the current
 * filters. If there is already a length filter in the view, it will replace
 * it, otherwise, it will add the max length filter preserving the other
 * 
 * @param view
 * @param length
 */
public static void setMaxLength(EditText view, int length) {
    InputFilter curFilters[];
    InputFilter.LengthFilter lengthFilter;
    int idx;

    lengthFilter = new InputFilter.LengthFilter(length);

    curFilters = view.getFilters();
    if (curFilters != null) {
        for (idx = 0; idx < curFilters.length; idx++) {
            if (curFilters[idx] instanceof InputFilter.LengthFilter) {
                curFilters[idx] = lengthFilter;
                return;
            }
        }

        // since the length filter was not part of the list, but
        // there are filters, then add the length filter
        InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
        System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
        newFilters[curFilters.length] = lengthFilter;
        view.setFilters(newFilters);
    } else {
        view.setFilters(new InputFilter[] { lengthFilter });
    }
}

Due to goto10's observation, I put together the following code to protected against loosing other filters with setting the max length:

/**
 * This sets the maximum length in characters of an EditText view. Since the
 * max length must be done with a filter, this method gets the current
 * filters. If there is already a length filter in the view, it will replace
 * it, otherwise, it will add the max length filter preserving the other
 * 
 * @param view
 * @param length
 */
public static void setMaxLength(EditText view, int length) {
    InputFilter curFilters[];
    InputFilter.LengthFilter lengthFilter;
    int idx;

    lengthFilter = new InputFilter.LengthFilter(length);

    curFilters = view.getFilters();
    if (curFilters != null) {
        for (idx = 0; idx < curFilters.length; idx++) {
            if (curFilters[idx] instanceof InputFilter.LengthFilter) {
                curFilters[idx] = lengthFilter;
                return;
            }
        }

        // since the length filter was not part of the list, but
        // there are filters, then add the length filter
        InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
        System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
        newFilters[curFilters.length] = lengthFilter;
        view.setFilters(newFilters);
    } else {
        view.setFilters(new InputFilter[] { lengthFilter });
    }
}
回复 原文
鼻尖触碰 2024-09-17 20:48:55
//Set Length filter. Restricting to 10 characters only
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH)});

//Allowing only upper case characters
editText.setFilters(new InputFilter[]{new InputFilter.AllCaps()});

//Attaching multiple filters
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH), new InputFilter.AllCaps()});

//Set Length filter. Restricting to 10 characters only
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH)});

//Allowing only upper case characters
editText.setFilters(new InputFilter[]{new InputFilter.AllCaps()});

//Attaching multiple filters
editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_LENGTH), new InputFilter.AllCaps()});
回复 原文
最笨的告白 2024-09-17 20:48:55

实现此目的的另一种方法是将以下定义添加到 XML 文件中：

<EditText
    android:id="@+id/input"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:maxLength="6"
    android:hint="@string/hint_gov"
    android:layout_weight="1"/>

这会将 EditText 小部件的最大长度限制为 6 个字符。

Another way you can achieve this is by adding the following definition to the XML file:

<EditText
    android:id="@+id/input"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:maxLength="6"
    android:hint="@string/hint_gov"
    android:layout_weight="1"/>

This will limit the maximum length of the EditText widget to 6 characters.

回复 原文
记忆里有你的影子 2024-09-17 20:48:55

XML

android:maxLength="10"

以编程方式：

int maxLength = 10;
InputFilter[] filters = new InputFilter[1];
filters[0] = new InputFilter.LengthFilter(maxLength);
yourEditText.setFilters(filters);

注意：在内部，EditText & TextView 解析 XML 中 android:maxLength 的值，并使用 InputFilter.LengthFilter() 来应用它。

请参阅： TextView.java#L1564

XML

android:maxLength="10"

Programmatically:

int maxLength = 10;
InputFilter[] filters = new InputFilter[1];
filters[0] = new InputFilter.LengthFilter(maxLength);
yourEditText.setFilters(filters);

Note: internally, EditText & TextView parse the value of android:maxLength in XML and use InputFilter.LengthFilter() to apply it.

See: TextView.java#L1564

回复 原文
安穩 2024-09-17 20:48:55

从 material.io 中，您可以将 TextInputEditText 与 TextInputLayout 结合使用：

<com.google.android.material.textfield.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:counterEnabled="true"
    app:counterMaxLength="1000"
    app:passwordToggleEnabled="false">

    <com.google.android.material.textfield.TextInputEditText
        android:id="@+id/edit_text"
        android:hint="@string/description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:maxLength="1000"
        android:gravity="top|start"
        android:inputType="textMultiLine|textNoSuggestions"/>

</com.google.android.material.textfield.TextInputLayout>

您可以使用drawable配置密码EditText：

password example

或者您可以使用/不使用计数器来限制文本长度：

counter example

依赖项：

implementation 'com.google.android.material:material:1.1.0-alpha02'

From material.io, you can use TextInputEditText combined with TextInputLayout:

<com.google.android.material.textfield.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:counterEnabled="true"
    app:counterMaxLength="1000"
    app:passwordToggleEnabled="false">

    <com.google.android.material.textfield.TextInputEditText
        android:id="@+id/edit_text"
        android:hint="@string/description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:maxLength="1000"
        android:gravity="top|start"
        android:inputType="textMultiLine|textNoSuggestions"/>

</com.google.android.material.textfield.TextInputLayout>

You can configure a password EditText with drawable:

password example

Or you can limit text length with/without a counter:

counter example

Dependency:

implementation 'com.google.android.material:material:1.1.0-alpha02'
回复 原文
惯饮孤独 2024-09-17 20:48:55

Kotlin：

edit_text.filters += InputFilter.LengthFilter(10)

ZTE Blade A520 有奇怪的效果。当您键入超过 10 个符号（例如 15 个）时，EditText 将显示前 10 个，但其他 5 个不可见且不可访问。但是，当您使用 Backspace 删除符号时，它首先删除正确的 5 个符号，然后删除剩余的 10 个。要克服此行为，请使用

android:inputType="textNoSuggestions|textVisiblePassword"
android:maxLength="10"

或者这个：

android:inputType="textNoSuggestions"

或者这个，如果你想得到建议：

private class EditTextWatcher(private val view: EditText) : TextWatcher {
    private var position = 0
    private var oldText = ""

    override fun afterTextChanged(s: Editable?) = Unit

    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
        oldText = s?.toString() ?: ""
        position = view.selectionStart
    }

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        val newText = s?.toString() ?: ""
        if (newText.length > 10) {
            with(view) {
                setText(oldText)
                position = if (start > 0 && count > 2) {
                    // Text paste in nonempty field.
                    start
                } else {
                    if (position in 1..10 + 1) {
                        // Symbol paste in the beginning or middle of the field.
                        position - 1
                    } else {
                        if (start > 0) {
                            // Adding symbol to the end of the field.
                            start - 1
                        } else {
                            // Text paste in the empty field.
                            0
                        }
                    }
                }
                setSelection(position)
            }
        }
    }
}

// Usage:
editTextWatcher = EditTextWatcher(view.edit_text)
view.edit_text.addTextChangedListener(editTextWatcher)

Kotlin:

edit_text.filters += InputFilter.LengthFilter(10)

ZTE Blade A520 has strange effect. When you type more than 10 symbols (for instance, 15), EditText shows first 10, but other 5 are not visible and not accessible. But when you delete symbols with Backspace, it first deletes right 5 symbols and then removes remaining 10. To overcome this behaviour use a solution:

android:inputType="textNoSuggestions|textVisiblePassword"
android:maxLength="10"

or this:

android:inputType="textNoSuggestions"

or this, if you want to have suggestions:

private class EditTextWatcher(private val view: EditText) : TextWatcher {
    private var position = 0
    private var oldText = ""

    override fun afterTextChanged(s: Editable?) = Unit

    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
        oldText = s?.toString() ?: ""
        position = view.selectionStart
    }

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        val newText = s?.toString() ?: ""
        if (newText.length > 10) {
            with(view) {
                setText(oldText)
                position = if (start > 0 && count > 2) {
                    // Text paste in nonempty field.
                    start
                } else {
                    if (position in 1..10 + 1) {
                        // Symbol paste in the beginning or middle of the field.
                        position - 1
                    } else {
                        if (start > 0) {
                            // Adding symbol to the end of the field.
                            start - 1
                        } else {
                            // Text paste in the empty field.
                            0
                        }
                    }
                }
                setSelection(position)
            }
        }
    }
}

// Usage:
editTextWatcher = EditTextWatcher(view.edit_text)
view.edit_text.addTextChangedListener(editTextWatcher)
回复 原文
女皇必胜 2024-09-17 20:48:55

这是一个自定义的 EditText 类，允许长度过滤器与其他过滤器一起使用。
感谢 Tim Gallagher 的回答（如下）

import android.content.Context;
import android.text.InputFilter;
import android.util.AttributeSet;
import android.widget.EditText;


public class EditTextMultiFiltering extends EditText{

    public EditTextMultiFiltering(Context context) {
        super(context);
    }

    public EditTextMultiFiltering(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public EditTextMultiFiltering(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setMaxLength(int length) {
        InputFilter curFilters[];
        InputFilter.LengthFilter lengthFilter;
        int idx;

        lengthFilter = new InputFilter.LengthFilter(length);

        curFilters = this.getFilters();
        if (curFilters != null) {
            for (idx = 0; idx < curFilters.length; idx++) {
                if (curFilters[idx] instanceof InputFilter.LengthFilter) {
                    curFilters[idx] = lengthFilter;
                    return;
                }
            }

            // since the length filter was not part of the list, but
            // there are filters, then add the length filter
            InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
            System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
            newFilters[curFilters.length] = lengthFilter;
            this.setFilters(newFilters);
        } else {
            this.setFilters(new InputFilter[] { lengthFilter });
        }
    }
}

This is a custom EditText Class that allow Length filter to live along with other filters.
Thanks to Tim Gallagher's Answer (below)

import android.content.Context;
import android.text.InputFilter;
import android.util.AttributeSet;
import android.widget.EditText;


public class EditTextMultiFiltering extends EditText{

    public EditTextMultiFiltering(Context context) {
        super(context);
    }

    public EditTextMultiFiltering(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public EditTextMultiFiltering(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setMaxLength(int length) {
        InputFilter curFilters[];
        InputFilter.LengthFilter lengthFilter;
        int idx;

        lengthFilter = new InputFilter.LengthFilter(length);

        curFilters = this.getFilters();
        if (curFilters != null) {
            for (idx = 0; idx < curFilters.length; idx++) {
                if (curFilters[idx] instanceof InputFilter.LengthFilter) {
                    curFilters[idx] = lengthFilter;
                    return;
                }
            }

            // since the length filter was not part of the list, but
            // there are filters, then add the length filter
            InputFilter newFilters[] = new InputFilter[curFilters.length + 1];
            System.arraycopy(curFilters, 0, newFilters, 0, curFilters.length);
            newFilters[curFilters.length] = lengthFilter;
            this.setFilters(newFilters);
        } else {
            this.setFilters(new InputFilter[] { lengthFilter });
        }
    }
}
回复 原文
絕版丫頭 2024-09-17 20:48:55

xml 中的简单方法：

android:maxLength="4"

如果您需要在 xml 编辑文本中设置 4 个字符，请使用此

<EditText
    android:id="@+id/edtUserCode"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:maxLength="4"
    android:hint="Enter user code" />

it simple way in xml:

android:maxLength="4"

if u require to set 4 character in xml edit-text so,use this

<EditText
    android:id="@+id/edtUserCode"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:maxLength="4"
    android:hint="Enter user code" />
回复 原文
执手闯天涯 2024-09-17 20:48:55

以编程方式在 Java 上尝试一下：

myEditText(new InputFilter[] {new InputFilter.LengthFilter(CUSTOM_MAX_LEN)});

Try this for Java programmatically:

myEditText(new InputFilter[] {new InputFilter.LengthFilter(CUSTOM_MAX_LEN)});
回复 原文
烂人 2024-09-17 20:48:55

xml 中的简单方法：

android:maxLength="@{length}"

要以编程方式设置它，您可以使用以下函数

public static void setMaxLengthOfEditText(EditText editText, int length) {
    InputFilter[] filters = editText.getFilters();
    List arrayList = new ArrayList();
    int i2 = 0;
    if (filters != null && filters.length > 0) {
        int filtersSize = filters.length;
        int i3 = 0;
        while (i2 < filtersSize) {
            Object obj = filters[i2];
            if (obj instanceof LengthFilter) {
                arrayList.add(new LengthFilter(length));
                i3 = 1;
            } else {
                arrayList.add(obj);
            }
            i2++;
        }
        i2 = i3;
    }
    if (i2 == 0) {
        arrayList.add(new LengthFilter(length));
    }
    if (!arrayList.isEmpty()) {
        editText.setFilters((InputFilter[]) arrayList.toArray(new InputFilter[arrayList.size()]));
    }
}

it simple way in xml:

android:maxLength="@{length}"

for setting it programmatically you can use the following function

public static void setMaxLengthOfEditText(EditText editText, int length) {
    InputFilter[] filters = editText.getFilters();
    List arrayList = new ArrayList();
    int i2 = 0;
    if (filters != null && filters.length > 0) {
        int filtersSize = filters.length;
        int i3 = 0;
        while (i2 < filtersSize) {
            Object obj = filters[i2];
            if (obj instanceof LengthFilter) {
                arrayList.add(new LengthFilter(length));
                i3 = 1;
            } else {
                arrayList.add(obj);
            }
            i2++;
        }
        i2 = i3;
    }
    if (i2 == 0) {
        arrayList.add(new LengthFilter(length));
    }
    if (!arrayList.isEmpty()) {
        editText.setFilters((InputFilter[]) arrayList.toArray(new InputFilter[arrayList.size()]));
    }
}
回复 原文
这个俗人 2024-09-17 20:48:55

这工作正常...

android:maxLength="10"

这将只接受 10 个字符。

This works fine...

android:maxLength="10"

this will accept only 10 characters.

回复 原文
遇见了你 2024-09-17 20:48:55

我正在使用“maxLength”，但它对我不起作用。因此，根据我的经验，我尝试了一些事情。
我发现了问题。
我必须声明id。
然后：

android:id="@+id/editTextTest"
android:maxLength="10"

I was using "maxLength" but it didn't work for me. So, based on my experience, I tried a few things.
And I detected the problem.
I must declare the id.
Then:

android:id="@+id/editTextTest"
android:maxLength="10"
回复 原文
猫瑾少女 2024-09-17 20:48:55

我看到了很多好的解决方案，但我想给出一个我认为更完整且用户友好的解决方案，其中包括：

1、限制长度。
2, 如果输入更多，则回调以触发您的吐司。
3、光标可以在中间或尾部。
4、用户可以通过粘贴字符串的方式输入。
5、始终丢弃溢出输入并保留原点。

public class LimitTextWatcher implements TextWatcher {

    public interface IF_callback{
        void callback(int left);
    }

    public IF_callback if_callback;

    EditText editText;
    int maxLength;

    int cursorPositionLast;
    String textLast;
    boolean bypass;

    public LimitTextWatcher(EditText editText, int maxLength, IF_callback if_callback) {

        this.editText = editText;
        this.maxLength = maxLength;
        this.if_callback = if_callback;
    }

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

        if (bypass) {

            bypass = false;

        } else {

            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append(s);
            textLast = stringBuilder.toString();

            this.cursorPositionLast = editText.getSelectionStart();
        }
    }

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

    }

    @Override
    public void afterTextChanged(Editable s) {
        if (s.toString().length() > maxLength) {

            int left = maxLength - s.toString().length();

            bypass = true;
            s.clear();

            bypass = true;
            s.append(textLast);

            editText.setSelection(this.cursorPositionLast);

            if (if_callback != null) {
                if_callback.callback(left);
            }
        }

    }

}


edit_text.addTextChangedListener(new LimitTextWatcher(edit_text, MAX_LENGTH, new LimitTextWatcher.IF_callback() {
    @Override
    public void callback(int left) {
        if(left <= 0) {
            Toast.makeText(MainActivity.this, "input is full", Toast.LENGTH_SHORT).show();
        }
    }
}));

我失败的是，如果用户突出显示当前输入的一部分并尝试粘贴很长的字符串，我不知道如何恢复突出显示。

例如，最大长度设置为10，用户输入“12345678”，并将“345”标记为突出显示，并尝试粘贴超出限制的字符串“0000”。

当我尝试使用 edit_text.setSelection(start=2, end=4) 恢复原始状态时，结果是，它只是插入 2 个空格作为“12 345 678”，而不是原始突出显示。我希望有人能解决这个问题。

I had saw a lot of good solutions, but I'd like to give a what I think as more complete and user-friendly solution, which include:

1, Limit length.
2, If input more, give a callback to trigger your toast.
3, Cursor can be at middle or tail.
4, User can input by paste a string.
5, Always discard overflow input and keep origin.

public class LimitTextWatcher implements TextWatcher {

    public interface IF_callback{
        void callback(int left);
    }

    public IF_callback if_callback;

    EditText editText;
    int maxLength;

    int cursorPositionLast;
    String textLast;
    boolean bypass;

    public LimitTextWatcher(EditText editText, int maxLength, IF_callback if_callback) {

        this.editText = editText;
        this.maxLength = maxLength;
        this.if_callback = if_callback;
    }

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

        if (bypass) {

            bypass = false;

        } else {

            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append(s);
            textLast = stringBuilder.toString();

            this.cursorPositionLast = editText.getSelectionStart();
        }
    }

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

    }

    @Override
    public void afterTextChanged(Editable s) {
        if (s.toString().length() > maxLength) {

            int left = maxLength - s.toString().length();

            bypass = true;
            s.clear();

            bypass = true;
            s.append(textLast);

            editText.setSelection(this.cursorPositionLast);

            if (if_callback != null) {
                if_callback.callback(left);
            }
        }

    }

}


edit_text.addTextChangedListener(new LimitTextWatcher(edit_text, MAX_LENGTH, new LimitTextWatcher.IF_callback() {
    @Override
    public void callback(int left) {
        if(left <= 0) {
            Toast.makeText(MainActivity.this, "input is full", Toast.LENGTH_SHORT).show();
        }
    }
}));

What I failed to do is, if user highlight a part of the current input and try to paste an very long string, I don't know how to restore the highlight.

Such as, max length is set to 10, user inputed '12345678', and mark '345' as highlight, and try to paste a string of '0000' which will exceed limitation.

When I try to use edit_text.setSelection(start=2, end=4) to restore origin status, the result is, it just insert 2 space as '12 345 678', not the origin highlight. I'd like someone solve that.

回复 原文
╰◇生如夏花灿烂 2024-09-17 20:48:55

您可以在EditText中使用android:maxLength="10"。（这里限制最多10个字符）

You can use android:maxLength="10" in the EditText.(Here the limit is upto 10 characters)

回复 原文
╰沐子 2024-09-17 20:48:54

文档

示例

android:maxLength="10"

Documentation

Example

android:maxLength="10"
回复 原文
诠释孤独 2024-09-17 20:48:54

使用输入过滤器来限制文本视图的最大长度。

TextView editEntryView = new TextView(...);
InputFilter[] filterArray = new InputFilter[1];
filterArray[0] = new InputFilter.LengthFilter(8);
editEntryView.setFilters(filterArray);

use an input filter to limit the max length of a text view.

TextView editEntryView = new TextView(...);
InputFilter[] filterArray = new InputFilter[1];
filterArray[0] = new InputFilter.LengthFilter(8);
editEntryView.setFilters(filterArray);
回复 原文
初吻给了烟 2024-09-17 20:48:54
EditText editText = new EditText(this);
int maxLength = 3;    
editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});

EditText editText = new EditText(this);
int maxLength = 3;    
editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});
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