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Java - How to convert camel case or Java identifier to a displayable string?

[Updated: May 18, 2018, Created: May 18, 2018]

Java String Manipulation Java 

Following example shows how to convert camel case string to a displayable (space separated) string. This also works for Java identifiers (method, field, class names)

package com.logicbig.example;

import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Arrays;

public class DisplayableStrings {
  //to split camel case
  public static String[] splitByCapitalLetters(String input) {
      return input.split("(?=\\p{Upper})");
  }

  public static String fromJavaIdentifierToDisplayableString(String input) {
      String rv = "";
      for (String s : splitByCapitalLetters(input)) {
          rv += s + " ";
      }
      rv = rv.trim();
      if (Character.isLowerCase(rv.charAt(0))) {
          rv = Character.toUpperCase(rv.charAt(0)) + rv.substring(1, rv.length());
      }
      return rv;
  }

  public static void main(String[] args) {
      String s = fromJavaIdentifierToDisplayableString(BigDecimal.class.getSimpleName());
      System.out.println(s);
      Arrays.stream(ArrayList.class.getDeclaredMethods()).map(Method::getName)
            .forEach(f -> {
                System.out.println(f + " -> " + fromJavaIdentifierToDisplayableString(f));
            });
  }
}
Big Decimal
add -> Add
add -> Add
add -> Add
remove -> Remove
remove -> Remove
get -> Get
clone -> Clone
indexOf -> Index Of
clear -> Clear
isEmpty -> Is Empty
lastIndexOf -> Last Index Of
contains -> Contains
replaceAll -> Replace All
size -> Size
subList -> Sub List
toArray -> To Array
toArray -> To Array
iterator -> Iterator
spliterator -> Spliterator
addAll -> Add All
addAll -> Add All
set -> Set
access$000 -> Access$000
readObject -> Read Object
writeObject -> Write Object
forEach -> For Each
newCapacity -> New Capacity
ensureCapacity -> Ensure Capacity
trimToSize -> Trim To Size
hugeCapacity -> Huge Capacity
retainAll -> Retain All
removeAll -> Remove All
removeIf -> Remove If
removeIf -> Remove If
sort -> Sort
listIterator -> List Iterator
listIterator -> List Iterator
removeRange -> Remove Range
rangeCheckForAdd -> Range Check For Add
outOfBoundsMsg -> Out Of Bounds Msg
outOfBoundsMsg -> Out Of Bounds Msg
elementData -> Element Data
grow -> Grow
grow -> Grow
elementAt -> Element At
fastRemove -> Fast Remove
shiftTailOverGap -> Shift Tail Over Gap
batchRemove -> Batch Remove
nBits -> N Bits
setBit -> Set Bit
isClear -> Is Clear
checkInvariants -> Check Invariants

See Also