Android限制用户输入

Question

I'm trying to restrict user input. If the user inputs consecutive digits eg,like this 1232334, and consecutive special characters eg, !@%$^&#@$*. But it will allow user to input ordinal numbers like 1st, 2nd, etc. And also it will allow John 13:12. A verse type.

This is what I've tried: (I used InputFilter)

 InputFilter filter = new InputFilter() { 
        @Override
        public CharSequence filter(CharSequence source, int start, int end,
                Spanned dest, int dstart, int dend) {
            // TODO Auto-generated method stub
            for (int i = start; i < end; i++) { 
                if (!Character.isLetterOrDigit(source.charAt(i))) { 
                    return ""; 
                    } 
             } 
             return null; 
        } 
    }; 

    et.setFilters(new InputFilter[]{filter}); 

But it won't let me type special characters, and it can accept consecutive digits. Does anyone know how to achieve my requirements? Your is pretty much appreciated. Thanks.

Answer 1

Try this Tested solution.

import android.app.Activity;
import android.os.Bundle;
import android.text.InputFilter;
import android.text.Spanned;
import android.widget.EditText;

public class MainActivity extends Activity {

    EditText et;
    String specialCharSet = "!@%$^&#@$*";

    InputFilter filter = new InputFilter() {
        @Override
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
            String tmp;
            try {
                tmp = (et.getText().toString()).substring(et.getText().toString().length() - 2, et.getText().toString().length());

                if (Character.isDigit(tmp.charAt(0)) && Character.isDigit(tmp.charAt(1)) && Character.isDigit(source.toString().charAt(0))) {
                    return "";
                }

                if (specialCharSet.contains("" + tmp.charAt(1)) && specialCharSet.contains("" + source)) {
                    return "";
                }
            } catch (Exception e) {
                if (et.getText().toString().length() >= 1 && specialCharSet.contains("" + et.getText().toString().charAt(0)) && specialCharSet.contains(source)) {
                    return "";
                }
            }

            return null;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et = (EditText) findViewById(R.id.et);
        et.setFilters(new InputFilter[] { filter });

    }

}

Answer 2

I suggest to change your implementation the following way:

• Build Regular Expressions for both patterns of input you allow
• Build the string that would result from the user's input with the information from source, start, end, dest, dtsart and dend
• Check if this string matches one of your two regular expressions, if not return ""

That should do it more or less. I've done something similar a few month ago. If you're lucky, I can find the code and paste it here, when I'm home this evening :) But in general this should be pretty straight forward. If you're unsure about the values of source, start, end, dest, dstart and dend, check them in the debugger, to get a better understanding.

-- Update -- The good thing is, I found my code in a question I once posted here ;)

public class MoneyFilter implements InputFilter {

    @Override
    public CharSequence filter(CharSequence source, int start, int end,
        Spanned dest, int dstart, int dend) {

        // The regex to test the string
        String testRegex = "^\\d+\\,?\\d{0,2}$";

        String s = source.toString();
        String d = dest.toString();

        // Build the string that would return from the user's input
        String r = d.substring(0, dstart) + s.substring(start, end)
            + d.substring(dend);

        // And check it
        if (r.matches(testRegex)) {
            return null;
        } else {
            return "";
        }
    }
}

You'll off course need different regular expressions to match the string, but the rest of the code should work.

hope this helps,

regards,

Hans