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 int PAD_LIMIT = 8192;

    public static String leftPad(String str, int size) {
        return leftPad(str, size, ' ');
    }//from w ww .  ja v  a  2 s  .c om

    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;
        }
        if (pads > PAD_LIMIT) {
            return leftPad(str, size, String.valueOf(padChar));
        }
        return padding(pads, padChar).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;
        }
        if ((padLen == 1) && (pads <= PAD_LIMIT)) {
            return leftPad(str, size, padStr.charAt(0));
        }
        if (pads == padLen) {
            return padStr.concat(str);
        }
        if (pads < padLen) {
            return padStr.substring(0, pads).concat(str);
        }
        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);
    }

    private static String padding(int repeat, char padChar) throws IndexOutOfBoundsException {
        if (repeat < 0) {
            throw new IndexOutOfBoundsException("Cannot pad a negative amount: " + repeat);
        }
        char[] buf = new char[repeat];
        for (int i = 0; i < buf.length; i++) {
            buf[i] = padChar;
        }
        return new String(buf);
    }

    public static boolean isEmpty(String str) {
        return (str == null) || (str.length() == 0);
    }

    public static String substring(String str, int start) {
        if (str == null) {
            return null;
        }
        if (start < 0) {
            start = str.length() + start;
        }
        if (start < 0) {
            start = 0;
        }
        if (start > str.length()) {
            return "";
        }
        return str.substring(start);
    }

    public static String substring(String str, int start, int end) {
        if (str == null) {
            return null;
        }
        if (end < 0) {
            end = str.length() + end;
        }
        if (start < 0) {
            start = str.length() + start;
        }
        if (end > str.length()) {
            end = str.length();
        }
        if (start > end) {
            return "";
        }
        if (start < 0) {
            start = 0;
        }
        if (end < 0) {
            end = 0;
        }
        return str.substring(start, end);
    }
}

Related

1. leftPad(String str, int length, char c)
2. leftPad(String str, int length, char padding)
3. leftPad(String str, int maxLength, char placeholder)
4. leftPad(String str, int num, String padStr)
5. leftPad(String str, int pad)
6. leftPad(String str, int size)
7. leftPad(String str, int size)
8. leftPad(String str, int size)
9. leftPad(String str, int size)