diff --git a/java-strings/src/main/java/com/baeldung/string/padding/StringPaddingUtil.java b/java-strings/src/main/java/com/baeldung/string/padding/StringPaddingUtil.java new file mode 100644 index 0000000000..80d05bb42a --- /dev/null +++ b/java-strings/src/main/java/com/baeldung/string/padding/StringPaddingUtil.java @@ -0,0 +1,34 @@ +package com.baeldung.string.padding; + +public class StringPaddingUtil { + + public static String padLeftSpaces(String inputString, int length) { + if (inputString.length() >= length) { + return inputString; + } + StringBuilder sb = new StringBuilder(); + while (sb.length() < length - inputString.length()) { + sb.append(' '); + } + sb.append(inputString); + + return sb.toString(); + } + + public static String padLeft(String inputString, int length) { + if (inputString.length() >= length) { + return inputString; + } + StringBuilder sb = new StringBuilder(); + for (int i = 0; i < length; i++) { + sb.append(' '); + } + return sb.substring(inputString.length()) + inputString; + } + + public static String padLeftZeros(String inputString, int length) { + return String + .format("%1$" + length + "s", inputString) + .replace(' ', '0'); + } +} diff --git a/java-strings/src/test/java/com/baeldung/string/padding/StringPaddingUtilUnitTest.java b/java-strings/src/test/java/com/baeldung/string/padding/StringPaddingUtilUnitTest.java new file mode 100644 index 0000000000..f6a077a88e --- /dev/null +++ b/java-strings/src/test/java/com/baeldung/string/padding/StringPaddingUtilUnitTest.java @@ -0,0 +1,50 @@ +package com.baeldung.string.padding; + +import com.google.common.base.Strings; +import org.apache.commons.lang3.StringUtils; +import org.junit.Test; + +import static org.junit.Assert.assertEquals; + +public class StringPaddingUtilUnitTest { + + String inputString = "123456"; + String expectedPaddedStringSpaces = " 123456"; + String expectedPaddedStringZeros = "0000123456"; + int minPaddedStringLength = 10; + + @Test + public void givenString_whenPaddingWithSpaces_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringSpaces, StringPaddingUtil.padLeftSpaces(inputString, minPaddedStringLength)); + } + + @Test + public void givenString_whenPaddingWithSpacesUsingSubstring_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringSpaces, StringPaddingUtil.padLeft(inputString, minPaddedStringLength)); + } + + @Test + public void givenString_whenPaddingWithZeros_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringZeros, StringPaddingUtil.padLeftZeros(inputString, minPaddedStringLength)); + } + + @Test + public void givenString_whenPaddingWithSpacesUsingStringUtils_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringSpaces, StringUtils.leftPad(inputString, minPaddedStringLength)); + } + + @Test + public void givenString_whenPaddingWithZerosUsingStringUtils_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringZeros, StringUtils.leftPad(inputString, minPaddedStringLength, "0")); + } + + @Test + public void givenString_whenPaddingWithSpacesUsingGuavaStrings_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringSpaces, Strings.padStart(inputString, minPaddedStringLength, ' ')); + } + + @Test + public void givenString_whenPaddingWithZerosUsingGuavaStrings_thenStringPaddedMatches() { + assertEquals(expectedPaddedStringZeros, Strings.padStart(inputString, minPaddedStringLength, '0')); + } +}