科特林：

edit_text.filters += InputFilter.LengthFilter(10)

中兴刀片A520具有奇怪的效果。当您键入超过10个符号（例如15个）时，EditText将显示前10个符号，但其他5个符号不可见且不可访问。但当您使用Backspace删除符号时，它会先删除右边的5个符号，然后删除剩下的10个符号。要克服这种行为，请使用以下解决方案：

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

或者：

android:inputType="textNoSuggestions"

或者，如果您想获得建议：

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)

由于goto10的观察，我将以下代码组合在一起，通过设置最大长度来防止丢失其他过滤器：

/**
 * 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 });
    }
}

这是一个自定义的EditText类，允许长度筛选器与其他筛选器一起使用。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 });
        }
    }
}

我曾经遇到过这个问题，我认为我们缺少一种经过充分解释的方法，在不丢失已经设置的过滤器的情况下，通过编程实现这一点。

在XML中设置长度：

由于接受的答案正确地表明，如果您想为EditText定义一个固定长度，并且以后不会再更改，只需在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，如果创建一个新的InputFilter并将其设置为EditText，则会丢失所有其他已定义的过滤器（例如maxLines、inputType等），这些过滤器可能是通过XML或编程添加的。

所以这是错误的：

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，添加新的过滤器（在本例中为maxLength），并将过滤器设置回EditText，如下所示：

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);

然而，Kotlin让每个人都更容易，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操作实现这一点：

editText.filters += InputFilter.LengthFilter(maxLength)

这很好。。。

android:maxLength=“10”

这将只接受10个字符。

以编程方式为Java尝试以下操作：

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