Shaped by Java LPAD and RPAD

September 17, 2018

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Formatting with Java LPAD and RPAD. Fill in the specified characters on the left and right of the string.

Javaand then use the SQL functionLPAD, ,RPADHere is a sample source that performs the same process as
These arefixed length formatThis is very useful when dealing with

LPAD... Returns a string with a repeated string filled in on the left side of the string so that the total number of characters is the specified number of digits.
RPAD... Returns a string with a repeated string filled in on the right side of the string so that the total number of characters is the specified number of digits.

sample program

/** * LPADを行います。 * 文字列[str]の左に指定した文字列[addStr]を[len]に * 満たすまで挿入します。 * @param str 対象文字列 * @param len 補充するまでの桁数（LPADを行った後のサイズを指定します。） * @param addStr 挿入する文字列 * @return 変換後の文字列。 */ public static String lpad(String str, int len, String addStr) { return fillString(str, “L”, len, addStr); } /** * Perform RPAD. * Add the specified string [addStr] to the right of the string [str] to [len] * Insert until full. * @param str target string * @param len Number of digits to refill (specifies the size after performing RPAD) * @param addStr String to insert * @return The string after conversion. */ public static String rpad(String str, int len, String addStr) { return fillString(str, “R”, len, addStr); } /** * Add the string [addStr] to be added to the string [str] * Insert at [position] until [len] is filled. * * *Even if [str] is null or an empty literal, use [addStr] * Returns the result inserted until [len] is filled. * @param str target string * @param position Insert before ⇒ L or l Insert after ⇒ R or r * @param len Number of digits to replenish * @param addStr String to insert * @return The string after conversion. */ public static String fillString(String str, String position, int len, String addStr) { if (addStr == null || addStr.length() == 0) { throw new IllegalArgumentException (“The value of the string to be inserted is invalid. addStr=”+addStr); } if (str == null) { str = “”; } StringBuffer buffer = new StringBuffer(str); while (len > buffer.length()) { if (position.equalsIgnoreCase(“l”)) { int sum = buffer.length() + addStr.length(); if (sum > len) { addStr = addStr.substring (0,addStr.length() – (sum – len)); buffer.insert(0, addStr); }else{ buffer.insert(0, addStr); } } else { buffer.append(addStr); } } if (buffer.length() == len) { return buffer.toString(); } return buffer.toString().substring(0, len); }

Execution Result

◆Example of Execution

public static void main(String[] args) {
    // For lpad, fill in the spaces to the left until there are 5 digits.
    String ret = lpad("abc", 5 , " ");
    System.out.println("'" + ret + "'");

    // For rpad. fill space to the right until 5 digits.
    ret = rpad("abc", 5 , " ");
    System.out.println("'" + ret + "'");

    // If null
    ret = rpad(null, 5 , " ");
    System.out.println("'" + ret + "'"); // if null
}

◆Output result

'abc'
' 'abc '
' '

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