Java tutorial
/* * Copyright (C) 2008 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.google.gson; import com.google.gson.internal.$Gson$Preconditions; import java.math.BigDecimal; import java.math.BigInteger; import com.google.gson.internal.LazilyParsedNumber; /** * A class representing a Json primitive value. A primitive value * is either a String, a Java primitive, or a Java primitive * wrapper type. * * @author Inderjeet Singh * @author Joel Leitch */ public final class JsonPrimitive extends JsonElement { private final Object value; /** * Create a primitive containing a boolean value. * * @param bool the value to create the primitive with. */ public JsonPrimitive(Boolean bool) { value = $Gson$Preconditions.checkNotNull(bool); } /** * Create a primitive containing a {@link Number}. * * @param number the value to create the primitive with. */ public JsonPrimitive(Number number) { value = $Gson$Preconditions.checkNotNull(number); } /** * Create a primitive containing a String value. * * @param string the value to create the primitive with. */ public JsonPrimitive(String string) { value = $Gson$Preconditions.checkNotNull(string); } /** * Create a primitive containing a character. The character is turned into a one character String * since Json only supports String. * * @param c the value to create the primitive with. */ public JsonPrimitive(Character c) { // convert characters to strings since in JSON, characters are represented as a single // character string value = $Gson$Preconditions.checkNotNull(c).toString(); } /** * Returns the same value as primitives are immutable. * @since 2.8.2 */ @Override public JsonPrimitive deepCopy() { return this; } /** * Check whether this primitive contains a boolean value. * * @return true if this primitive contains a boolean value, false otherwise. */ public boolean isBoolean() { return value instanceof Boolean; } /** * convenience method to get this element as a boolean value. * * @return get this element as a primitive boolean value. */ @Override public boolean getAsBoolean() { if (isBoolean()) { return ((Boolean) value).booleanValue(); } // Check to see if the value as a String is "true" in any case. return Boolean.parseBoolean(getAsString()); } /** * Check whether this primitive contains a Number. * * @return true if this primitive contains a Number, false otherwise. */ public boolean isNumber() { return value instanceof Number; } /** * convenience method to get this element as a Number. * * @return get this element as a Number. * @throws NumberFormatException if the value contained is not a valid Number. */ @Override public Number getAsNumber() { return value instanceof String ? new LazilyParsedNumber((String) value) : (Number) value; } /** * Check whether this primitive contains a String value. * * @return true if this primitive contains a String value, false otherwise. */ public boolean isString() { return value instanceof String; } /** * convenience method to get this element as a String. * * @return get this element as a String. */ @Override public String getAsString() { if (isNumber()) { return getAsNumber().toString(); } else if (isBoolean()) { return ((Boolean) value).toString(); } else { return (String) value; } } /** * convenience method to get this element as a primitive double. * * @return get this element as a primitive double. * @throws NumberFormatException if the value contained is not a valid double. */ @Override public double getAsDouble() { return isNumber() ? getAsNumber().doubleValue() : Double.parseDouble(getAsString()); } /** * convenience method to get this element as a {@link BigDecimal}. * * @return get this element as a {@link BigDecimal}. * @throws NumberFormatException if the value contained is not a valid {@link BigDecimal}. */ @Override public BigDecimal getAsBigDecimal() { return value instanceof BigDecimal ? (BigDecimal) value : new BigDecimal(value.toString()); } /** * convenience method to get this element as a {@link BigInteger}. * * @return get this element as a {@link BigInteger}. * @throws NumberFormatException if the value contained is not a valid {@link BigInteger}. */ @Override public BigInteger getAsBigInteger() { return value instanceof BigInteger ? (BigInteger) value : new BigInteger(value.toString()); } /** * convenience method to get this element as a float. * * @return get this element as a float. * @throws NumberFormatException if the value contained is not a valid float. */ @Override public float getAsFloat() { return isNumber() ? getAsNumber().floatValue() : Float.parseFloat(getAsString()); } /** * convenience method to get this element as a primitive long. * * @return get this element as a primitive long. * @throws NumberFormatException if the value contained is not a valid long. */ @Override public long getAsLong() { return isNumber() ? getAsNumber().longValue() : Long.parseLong(getAsString()); } /** * convenience method to get this element as a primitive short. * * @return get this element as a primitive short. * @throws NumberFormatException if the value contained is not a valid short value. */ @Override public short getAsShort() { return isNumber() ? getAsNumber().shortValue() : Short.parseShort(getAsString()); } /** * convenience method to get this element as a primitive integer. * * @return get this element as a primitive integer. * @throws NumberFormatException if the value contained is not a valid integer. */ @Override public int getAsInt() { return isNumber() ? getAsNumber().intValue() : Integer.parseInt(getAsString()); } @Override public byte getAsByte() { return isNumber() ? getAsNumber().byteValue() : Byte.parseByte(getAsString()); } @Override public char getAsCharacter() { return getAsString().charAt(0); } @Override public int hashCode() { if (value == null) { return 31; } // Using recommended hashing algorithm from Effective Java for longs and doubles if (isIntegral(this)) { long value = getAsNumber().longValue(); return (int) (value ^ (value >>> 32)); } if (value instanceof Number) { long value = Double.doubleToLongBits(getAsNumber().doubleValue()); return (int) (value ^ (value >>> 32)); } return value.hashCode(); } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null || getClass() != obj.getClass()) { return false; } JsonPrimitive other = (JsonPrimitive) obj; if (value == null) { return other.value == null; } if (isIntegral(this) && isIntegral(other)) { return getAsNumber().longValue() == other.getAsNumber().longValue(); } if (value instanceof Number && other.value instanceof Number) { double a = getAsNumber().doubleValue(); // Java standard types other than double return true for two NaN. So, need // special handling for double. double b = other.getAsNumber().doubleValue(); return a == b || (Double.isNaN(a) && Double.isNaN(b)); } return value.equals(other.value); } /** * Returns true if the specified number is an integral type * (Long, Integer, Short, Byte, BigInteger) */ private static boolean isIntegral(JsonPrimitive primitive) { if (primitive.value instanceof Number) { Number number = (Number) primitive.value; return number instanceof BigInteger || number instanceof Long || number instanceof Integer || number instanceof Short || number instanceof Byte; } return false; } }