com.github.ibole.infrastructure.common.utils.ToStringUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of infrastructure-all Show documentation
The all in one project of ibole infrastructure
The newest version!
package com.github.ibole.infrastructure.common.utils;

/**
 * This class consists exclusively of static methods to help in {@link Object#toString()} method
 * overriding.
 * 
 * Pattern:
 * 
 * 
 * @Override
 * public String toString() {
 *   final StringBuilder sb = ToStringUtil.start("a", a);
 *   ToStringUtil.append(sb, "b", b);
 *   ToStringUtil.append(sb, "c", c);
 *   return ToStringUtil.end(sb);
 * }
 * 
 */
public final class ToStringUtil {

  private static final int CAPACITY = 128;

  /*
   * Suppresses default constructor, ensuring non-instantiability
   */
  @SuppressWarnings("nls")
  private ToStringUtil() {
    throw new AssertionError("not aimed to be instantiated");
  }

  /**
   * Creates and return a new {@code StringBuilder} with the given {@code
   * field} and {@code value} appended after the opening brace.
   * 
   * The returned buffer is created with a default capacity of {@code 128}.
   * 
   * @param field the name of the field
   * @param value the value of the field
   * @return a new buffer
   * @see StringBuilder#StringBuilder(int)
   * @see #start(int, String, Object)
   */
  public static StringBuilder start(final String field, final Object value) {
    return start(CAPACITY, field, value);
  }

  /**
   * Creates and return a new {@code StringBuilder} with the given {@code
   * capacity}, and {@code field} and {@code value} appended after the opening brace.
   * 
   * @param capacity the capacity for the buffer
   * @param field the name of the field
   * @param value the value of the field
   * @return a new buffer
   * @throws NegativeArraySizeException if {@code capacity} is negative
   * @see #start(String, Object)
   */
  public static StringBuilder start(final int capacity, final String field, final Object value) {
    final StringBuilder buffer = new StringBuilder(capacity);
    buffer.append('{');
    makeKeyValue(buffer, field, value);
    return buffer;
  }

  /**
   * Appends the given {@code field} and {@code value} to {@code buffer}.
   * 
   * @param buffer the buffer to append {@code field} and {@code value} to
   * @param field the name of the field
   * @param value the value of the field
   * @return the buffer itself
   * @throws NullPointerException if {@code buffer} is {@code null}
   */
  public static StringBuilder append(final StringBuilder buffer, final String field,
      final Object value) {
    buffer.append(',');
    buffer.append(' ');
    makeKeyValue(buffer, field, value);
    return buffer;
  }

  /**
   * Appends the given {@code field} and {@code value} to {@code buffer}. The {@code char} value is
   * converted to a {@code String} before the method invokes and returns from
   * {@link #append(StringBuilder, String, Object)}.
   * 
   * @param buffer the buffer to append {@code field} and {@code value} to
   * @param field the name of the field
   * @param value the {@code char} value of the field
   * @return the buffer itself
   * @throws NullPointerException if {@code buffer} is {@code null}
   */
  public static StringBuilder append(final StringBuilder buffer, final String field,
      final char value) {
    return append(buffer, field, String.valueOf(value));
  }

  /**
   * Appends the closing brace and returns {@code buffer.toString()}.
   * 
   * @param buffer the buffer
   * @return {@code buffer.toString()} after appending the closing brace
   * @throws NullPointerException if {@code buffer} is {@code null}
   */
  public static String end(final StringBuilder buffer) {
    buffer.append('}');
    return buffer.toString();
  }

  private static void makeKeyValue(final StringBuilder buffer, final String field,
      final Object value) {
    buffer.append(field);
    buffer.append('=');
    buffer.append(value);
  }
}