Thread: Help with Character arrays

Deleted for privacy.

Unfortunately, Java's auto-boxing and auto-unboxing feature has a few gaps in what's covered. If you change your array to a char array rather than a Character array it should work.

public static String getDigits( char[] array ) {
        String str = new String(array);
        if (str == "") {
            return " ";
        }
        StringBuffer strBuff = new StringBuffer();
        char c;    
        for (int i = 0; i < str.length() ; i++) {
            c = str.charAt(i);         
            if (Character.isDigit(c)) {
                strBuff.append(c);
            }
        }
        return strBuff.toString();
    }
}

A better solution though is to simply straight up take a string rather than a char array which may or may not be filled.

edit:
fixed typo

Originally Posted by helloworld922

Unfortunately, Java's auto-boxing and auto-unboxing feature has a few gaps in what's covered. If you change your array to a char array rather than a Character array it should work.

char[] charArray = new char[] {array};

That won't compile, you're assigning a char[] to char.

Originally Posted by shanklove

My thought is that I need to take the array and make it into a String. Then take the string and take out everything that isn't a digit. Then return that String. But like I said, it's not working. Eclipse is throwing me the error:

Character[] charArray = new Character[] {array};

"Cannot convert from Character[] to Character

and

String str = new String(charArray);

"The constructor String(Character[]) is undefined".

You can do something like this... I think you don't need any String either a char[].

    public static String getDigits( Character[] array ) {
        if (array.length == 0) {
            return " ";
        }
        StringBuffer strBuff = new StringBuffer();
        char c;     
        for (int i = 0; i < array.length ; i++) {
            if (Character.isDigit(array[i])) {
                strBuff.append(array[i]);
            }
        }
        return strBuff.toString();
    }

Originally Posted by eyp

That won't compile, you're assigning a char[] to char.

oops, my bad. I accidentally mixed several thoughts together (yay for late nights)

Originally Posted by eyp

You can do something like this... I think you don't need any String either a char[].

    public static String getDigits( Character[] array ) {
        if (array.length == 0) {
            return " ";
        }
        StringBuffer strBuff = new StringBuffer();
        char c;     
        for (int i = 0; i < array.length ; i++) {
            if (Character.isDigit(array[i])) {
                strBuff.append(array[i]);
            }
        }
        return strBuff.toString();
    }

Looks good in theory, but it fails all of these tests:
It has something to do with "Lab03One.getDigits( values )"
Cannot convert from String to Character[].

Here is the whole test code, ignore the part about getMedian, all that works and compiled.

import static org.junit.Assert.*;
 
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
import org.junit.Test;
 
public class Lab03OneTest {
 
	@Test
	public void testGetMedianWithEmptyList() {
		Integer[] values   = { };
		Double    actual   = Lab03One.getMedian( values );
		Double    expected = 0.0;
 
		assertEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetMedianWithListOneValue() {
		Integer[] values   = { 5 };
		Double    actual   = Lab03One.getMedian( values );
		Double    expected = 5.0;
 
		assertEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetMedianWithListEvenValues() {
		Integer[] values   = { 22, 19, 20, 21 };
		Double    actual   = Lab03One.getMedian( values );
		Double    expected = 20.5;
 
		assertEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetMedianWithListOddValues() {
		Integer[] values   = { 42, -27, 8, -2, 59, 42, -1 };
		Double    actual   = Lab03One.getMedian( values );
		Double    expected = 8.0;
 
		assertEquals( "The result is incorrect", expected, actual );
	}
 
	@Test
	public void testGetDigitsWithListEmpty() {
		Character[] values   = { };
		Character[] actual   = Lab03One.getDigits( values );
		Character[] expected = { };
 
		assertArrayEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetDigitsWithListWithNoDigits() {
		Character[] values = { 'y', 'o', 'd', 'a' };
		Character[] actual = Lab03One.getDigits( values );
		Character[] expected = { };
 
		assertArrayEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetDigitsWithListWithLettersAndDigits() {
		Character[] values = { 'C', '-', '3', 'P', 'O' };
		Character[] actual = Lab03One.getDigits( values );
		Character[] expected = { '3' };
 
		assertArrayEquals( "The result is incorrect", expected, actual );
	}
	@Test
	public void testGetDigitsWithListWithDuplicatedDigits() {
		Character[] values = { 'a', '3', '2', 'b', '1', '2', 'c', '3', 'd' };
		Character[] actual = Lab03One.getDigits( values );
		Character[] expected = { '3', '2', '1', '2', '3' };
 
		assertArrayEquals( "The result is incorrect", expected, actual );
	}
 
}

Not a clue where to go from here =\
Also, I took out "char c" in the code you suggested (it was unused code)