题目

leftpad("foo", 5)

>> "  foo"

leftpad("foobar", 6)

>> "foobar"

leftpad("1", 2, "0")

>> "01"

解题
public class StringUtils {

    /**

     * @param originalStr the string we want to append to with spaces

     * @param size the target length of the string

     * @return a string

     */

    static public String leftPad(String originalStr, int size) {

        // Write your code here

        int n = originalStr.length();

        if(n>=size)

            return originalStr;

        int k = size - n;

        StringBuffer newStr = new StringBuffer();

        while(k>=1){

            newStr.append(' ');

            k--;

        }

        newStr.append(originalStr);

        return newStr.toString();

    }

    /**

     * @param originalStr the string we want to append to

     * @param size the target length of the string

     * @param padChar the character to pad to the left side of the string

     * @return a string

     */

    static public String leftPad(String originalStr, int size, char padChar) {

        // Write your code here

        int n = originalStr.length();

        if(n>=size)

            return originalStr;

        int k = size - n;

        StringBuffer newStr = new StringBuffer();

        while(k>=1){

            newStr.append(padChar);

            k--;

        }

        newStr.append(originalStr);

        return newStr.toString();

    }

}