java - Android:设置 EditText 每行最大字符数？

Question

有什么方法可以设置 EditText 字段中一行的最大字符数？我用 TextWatcher 试过了，但我真的做不到我想做的事。

我想设置最大行数和每行最大字符数。

示例:

插入的文本:

Lorem ipsum dolor sit amet consetetur sadipscing elitr.

结果(最大行数:10，每行最大字符数:20):

Lorem ipsum dolor
sit amet consetetur
sadipscing elitr.

编辑 XML:

    <EditText
    android:id="@+id/edittext"
    android:layout_width="wrap_content"
    android:layout_height="200dp"
    android:layout_alignParentRight="true"
    android:layout_marginLeft="15dp"
    android:layout_marginRight="15dp"
    android:background="@drawable/bgedit"
    android:gravity="top"
    android:lines="11"
    android:paddingLeft="35dp"
    android:paddingTop="20dp"
    android:singleLine="false"
    android:inputType="textMultiLine" 
   />

Answer 1

以下过滤器在每 n 个字符后添加一个新行:

public class AutoWrapFilter implements InputFilter {
    private final int mLineChars;

    public AutoWrapFilter(int pLineChars) {
        mLineChars = pLineChars;
    }

    @Override
    public CharSequence filter(CharSequence src, int srcStart, int srcEnd, Spanned dest, int destStart, int destEnd) {
        CharSequence original = dest.subSequence(0,destStart);
        CharSequence replacement = src.subSequence(srcStart,srcEnd);

        if(replacement.length() < 1){
            return null;
        }

        int lastLineCharIndex = -1;

        for (int j = destStart - 1; j >= 0; j--){
            if(original.charAt(j) == '\n'){
                lastLineCharIndex = j;
                break;
            }
        }

        int charsAfterLine = lastLineCharIndex < 0 ? original.length() : original.length() - lastLineCharIndex;

        StringBuilder sb = new StringBuilder();

        for (int k = 0; k < replacement.length(); k++){

            if(charsAfterLine == mLineChars+1){
                charsAfterLine = 0;
                sb.append('\n');
            }

            sb.append(replacement.charAt(k));
            charsAfterLine++;

        }


        return sb;
    }

    public static void applyAutoWrap(EditText et, int wrapLength){
        InputFilter[] filters = et.getFilters();
        InputFilter[] newFilters = Arrays.copyOf(filters, filters.length + 1);
        newFilters[filters.length] = new AutoWrapFilter(wrapLength);
        et.setFilters(newFilters);
    }
}

用法:

public class MyActivity extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        EditText edit = (EditText) findViewById(R.id.edit);

        AutoWrapFilter.applyAutoWrap(edit,10);

    }

}

结果:

此外，您还可以添加更多代码以在单词开头附加换行符，使其按单词换行。