Android Open Source - Abstract-Model Column

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License

The source code is released under:

Apache License

Java Source Code

package com.logician.abstractModel;
/*from   www. jav  a  2  s . c o m*/
import java.util.EnumSet;

/**
 * Class for defining columns in {@link Model} implementation tables. 
 * Each column generates its own SQL for its containing Model.
 * 
 * @see Model#getColumns()
 * @see Type
 * @author Logician
 *
 */

public final class Column {
  /**
   * The name of the column.
   */
  final String name;
  /**
   * The {@link Type} of the column.
   */
  final Type type;
  /**
   * The integer length of the column, or -1 if default.
   */
  final int length;
  /**
   * The NOT NULL flag for the column.
   */
  final EnumSet<Flag> flags;
  
  final String SQL;
    
  /**
   * Full detail constructor.
   * 
   * Use EnumSet.of() for quick flag-set creation.
   * @see EnumSet#of(Enum, Enum, Enum)
   * @param name The SQL-friendly name of the column.
   * @param type The Type of the column.
   * @param length The integer maximum size of the column.
   * @param flags If the column is to be defined as NOT NULL.
   */
  
  public Column(String name, Type type, int length, EnumSet<Flag> flags){
    this.name = name;
    this.type = type;
    this.length = length;
    this.flags = flags;
    
    this.SQL = getColumnSQL();
  }
  
  /**
   * Constructor that sets no flags.
   * 
   * @param name The SQL-friendly name of the column.
   * @param type The Type of the column.
   * @param length The integer maximum size of the column.
   */
  
  public Column(String name, Type type, int length){
    this(name, type, length, EnumSet.noneOf(Flag.class));
  }
  
  
  /**
   * Constructor that lets the length of the column fall back to the default size for the type.
   * 
   * Use EnumSet.of() for quick flag-set creation.
   * @see EnumSet#of(Enum, Enum, Enum)
   * @param name The SQL-friendly name of the column.
   * @param type The Type of the column.
   * @param flags An {@link EnumSet} of flags for this column.
   */
  public Column(String name, Type type, EnumSet<Flag> flags){
    this(name, type, -1, flags);
  }
  
  /**
   * Constructor for a Column with default length and no flags.
   * 
   * See the SQLite documentation for the default size for each column type.
   * 
   * @param name The SQL-friendly name of the column.
   * @param type The Type of the column.
   */
  
  public Column(String name, Type type){
    this(name, type, -1);
  }
    
  /**
   * The defining SQL for the column for the CREATE TABLE command of its containing model.
   * @return The column's SQL.
   */
  String getColumnSQL(){
    if(SQL != null)
      return SQL;
    else
      return new StringBuilder(getQuotedName())
      .append(' ')
      .append(getTypeText())
      .append(' ')
      .append(getFlagsText())
      .toString();
  }
  
  private String getQuotedName(){
    return "\"" + name + "\"";
  }
  
  
  private String getTypeText(){
    String text = null;
    switch(type){
    
    case BOOLEAN:
      text = "BOOLEAN";
      break;
    case BYTE_ARR:
      text ="BLOB" + getLength("");      
      break;      
    case INTEGER:
      text = "INT" + getLength("");
      break;    
    case DOUBLE:
      text = "DOUBLE";
      break;
    
    case FLOAT:
      text = "FLOAT";
      break;
      
    case LONG:
      text = "BIGINT";
      break;
    case JSON_OBJECT:
    case JSON_ARRAY:            
    case STRING:
      text = "TEXT";
      break;  
          
    }  
    
    return text;
    
  }
  
  private static final String UNIQUE = "UNIQUE";
  private static final String NOT_NULL = "NOT NULL";
  private static final String PRIMARY_KEY = "PRIMARY KEY";
  
  private String getFlagsText(){
    if(flags == null || flags.size() == 0)
      return "";
    
    StringBuilder builder = new StringBuilder();
    for(Flag flag : flags){
      if(builder.length() != 0)
        builder.append(' ');
      
      switch(flag){
      case UNIQUE:
        builder.append(UNIQUE);
        break;
      case NOT_NULL:
        builder.append(NOT_NULL);
        break;
      case PRIMARY_KEY:
        builder.append(PRIMARY_KEY);
      }
    }
    
    return builder.toString();
    
  }
  
  private String getLength(String defaultStr){
    return (length > 0) ? "(" + Integer.toString(length) + ")" : defaultStr;
  }
  
  /**
   * Returns false if {@code o} is not of class Column, else returns {@link #equals(Column)}.
   */
  
  @Override
  public boolean equals(Object o){
    if(!(o instanceof Column))
      return false;
    
    return equals((Column) o);
  }
  
  /**
   * Returns true only if all the fields of this Column are equal to those of {@code col}.
   * 
   * @param col The column to compare to.
   * @return If the columns' fields are all equal.
   */
  public boolean equals(Column col){
    return name == col.name && type == col.type && length == col.length && flags == col.flags;
  }

  /**
   * @see Flag
   * @return If the UNIQUE flag is set.
   */
  public boolean isUnique(){
    return flags.contains(Flag.UNIQUE);
  }
  
  /**
   * @see Flag
   * @return If the PRIMARY_KEY flag is set.
   */
  public boolean isPrimaryKey(){
    return flags.contains(Flag.PRIMARY_KEY);
  }
  
  /**
   * @see Flag
   * @return If the NOT_NULL flag is set.
   */
  
  public boolean isNotNull(){
    return flags.contains(Flag.NOT_NULL);
  }
  
  /**
   * An enumeration of the Java data types that will transfer (relatively) seamlessly to SQLite.
   * 
   * <p />
   * Types not found in this enumeration should implement
   * {@link BinarySerializable} and use {@linkplain #BYTE_ARR} 
   * or {@link JSONSerializable} and use {@linkplain #JSON_OBJECT}.
   * 
   *  
   * @author Logician
   *
   */

  public static enum Type {
    BOOLEAN, BYTE_ARR, INTEGER, DOUBLE, 
    FLOAT, LONG, STRING, JSON_OBJECT, JSON_ARRAY
  }
  
  /**
   * An enumeration of the currently available SQL column constraints.
   * 
   * @author Logician
   *
   */
  public static enum Flag{
    NOT_NULL, UNIQUE, PRIMARY_KEY
  }
}

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