以编程方式为Java尝试以下操作：

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

Xml

android:maxLength="10"

Java语言：

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);

科特林：

editText.filters += InputFilter.LengthFilter(maxLength)

我使用的是“maxLength”，但它对我不起作用。因此，根据我的经验，我尝试了一些方法。我发现了问题。我必须申报身份证。然后：

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

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 });
        }
    }
}

xml中的简单方式：

android:maxLength="@{length}"

要以编程方式设置它，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()]));
    }
}

xml中的简单方式：

android:maxLength="4"

如果您需要在xml编辑文本中设置4个字符，请使用

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