Java String Pad Left leftPad(String str, int size)

Description

left Pad

License

Apache License

Declaration

public static String leftPad(String str, int size) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

public class Main {
    private static final String EMPTY = "";
    /**/*from   ww  w  . j  ava  2  s.c  o  m*/
      * <p>The maximum size to which the padding constant(s) can expand.</p>
      */
    private static final int PAD_LIMIT = 8192;

    public static String leftPad(String str, int size) {
        return leftPad(str, size, ' ');
    }

    public static String leftPad(String str, int size, char padChar) {
        if (str == null) {
            return null;
        }
        int pads = size - str.length();
        if (pads <= 0) {
            return str; // returns original String when possible
        }
        if (pads > PAD_LIMIT) {
            return leftPad(str, size, String.valueOf(padChar));
        }
        return repeat(padChar, pads).concat(str);
    }

    public static String leftPad(String str, int size, String padStr) {
        if (str == null) {
            return null;
        }
        if (isEmpty(padStr)) {
            padStr = " ";
        }
        int padLen = padStr.length();
        int strLen = str.length();
        int pads = size - strLen;
        if (pads <= 0) {
            return str; // returns original String when possible
        }
        if (padLen == 1 && pads <= PAD_LIMIT) {
            return leftPad(str, size, padStr.charAt(0));
        }

        if (pads == padLen) {
            return padStr.concat(str);
        } else if (pads < padLen) {
            return padStr.substring(0, pads).concat(str);
        } else {
            char[] padding = new char[pads];
            char[] padChars = padStr.toCharArray();
            for (int i = 0; i < pads; i++) {
                padding[i] = padChars[i % padLen];
            }
            return new String(padding).concat(str);
        }
    }

    public static String repeat(String str, int repeat) {
        // Performance tuned for 2.0 (JDK1.4)

        if (str == null) {
            return null;
        }
        if (repeat <= 0) {
            return EMPTY;
        }
        int inputLength = str.length();
        if (repeat == 1 || inputLength == 0) {
            return str;
        }
        if (inputLength == 1 && repeat <= PAD_LIMIT) {
            return repeat(str.charAt(0), repeat);
        }

        int outputLength = inputLength * repeat;
        switch (inputLength) {
        case 1:
            return repeat(str.charAt(0), repeat);
        case 2:
            char ch0 = str.charAt(0);
            char ch1 = str.charAt(1);
            char[] output2 = new char[outputLength];
            for (int i = repeat * 2 - 2; i >= 0; i--, i--) {
                output2[i] = ch0;
                output2[i + 1] = ch1;
            }
            return new String(output2);
        default:
            StringBuilder buf = new StringBuilder(outputLength);
            for (int i = 0; i < repeat; i++) {
                buf.append(str);
            }
            return buf.toString();
        }
    }

    public static String repeat(String str, String separator, int repeat) {
        if (str == null || separator == null) {
            return repeat(str, repeat);
        } else {
            // given that repeat(String, int) is quite optimized, better to rely on it than try and splice this into it
            String result = repeat(str + separator, repeat);
            return removeEnd(result, separator);
        }
    }

    public static String repeat(char ch, int repeat) {
        char[] buf = new char[repeat];
        for (int i = repeat - 1; i >= 0; i--) {
            buf[i] = ch;
        }
        return new String(buf);
    }

    public static boolean isEmpty(String chkStr) {
        if (chkStr == null) {
            return true;
        } else {
            return "".equals(chkStr.trim()) ? true : false;
        }
    }

    public static boolean isEmpty(CharSequence chkSeq) {
        if (chkSeq == null) {
            return true;
        } else {
            return "".equals(chkSeq.toString().trim()) ? true : false;
        }
    }

    public static String toString(Object obj) {
        return obj == null ? "" : obj.toString();
    }

    public static String toString(Object obj, String nullStr) {
        return obj == null ? nullStr : obj.toString();
    }

    public static String removeEnd(String str, String remove) {
        if (isEmpty(str) || isEmpty(remove)) {
            return str;
        }
        if (str.endsWith(remove)) {
            return str.substring(0, str.length() - remove.length());
        }
        return str;
    }
}

Related

1. leftPad(String str, int size)
2. leftPad(String str, int size)
3. leftPad(String str, int size)
4. leftPad(String str, int size)
5. leftPad(String str, int size)
6. leftPad(String str, int size, char padChar)
7. leftPad(String str, int size, String delim)
8. leftPad(String str, int size, String padStr)
9. leftPad(String str, int size, String padStr)