ContentValues
/**
*This class is used to store a set of values that the {@link ContentResolver}
*can process.
*/
/* ContentValues
* 这个类被用于存储一个集合，这些值能被ContentResolver处理
* 该类只是简单的封装了HashMap
* */
public final classContentValues implementsParcelable {
public static final String TAG = "ContentValues";
/** Holds the actual values */
/* 拥有实际的值*/
private HashMap
/**
* Creates an empty set of values using the default initial size
*/
/* 创建一个空集合用于初始化默认大小，默认8个键值对
*/
public ContentValues() {
// Choosing a default size of 8 based onanalysis of typical
// consumption by applications.
//选择一个默认大小8，这个值是基于应用的典型消耗分析得出的。初始化8个键值对比较有效率
mValues= newHashMap
}
/**
* Creates an empty set of values using the given initial size
*
* @param size the initial size of the set of values
*/
/* 使用size参数创建一个size大小的空集合，
* @param size
*/
public ContentValues(int size) {
mValues= newHashMap
}
/**
* Creates a set of values copied from the given set
*
* @param from the values to copy
*/
/* 从一个给定的集合创建一个新集合
* 从一个ContentValues创建另一个ContentValues
* @param from
*/
public ContentValues(ContentValues from) {
mValues= newHashMap
}
/**
* Creates a set of values copied from the given HashMap. This is used
* by the Parcel unmarshalling code.
*
* @param values the values to start with
* {@hide}
*/
/* 从一个HashMap创建ContentValues，起始就是索引的赋值
* @param values
*/
private ContentValues(HashMap
mValues= values;
}
/*判断是否是同一个HashMap，HashMap的对象的索引值是同一个即相同*/
@Override
public booleanequals(Object object) {
if(!(object instanceofContentValues)) {
return false;
}
return mValues.equals(((ContentValues) object).mValues);
}
@Override
public inthashCode() {
return mValues.hashCode();
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
//添加一个值到集合
public voidput(String key, String value) {
mValues.put(key,value);
}
/**
* Adds all values from the passed in ContentValues.
*
* @param other the ContentValues from which to copy
*/
//将ContentValues里的HashMap的值全都赋值给当前ContentValues里的HashMap
public voidputAll(ContentValues other) {
mValues.putAll(other.mValues);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
//添加一个Byte类型的值到集合
public voidput(String key, Byte value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Short value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Integer value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Long value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Float value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Double value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, Boolean value) {
mValues.put(key,value);
}
/**
* Adds a value to the set.
*
* @param key the name of the value to put
* @param value the data for the value to put
*/
public voidput(String key, byte[]value) {
mValues.put(key,value);
}
/**
* Adds a null value to the set.
*
* @param key the name of the value to make null
*/
public voidputNull(String key) {
mValues.put(key,null);
}
/**
* Returns the number of values.
*
* @return the number of values
*/
//集合的大小，值的数量
public intsize() {
return mValues.size();
}
/**
* Remove a single value.
*
* @param key the name of the value to remove
*/
//移除一个键值对
public voidremove(String key) {
mValues.remove(key);
}
/**
* Removes all values.
*/
//清除所有键值对
public voidclear() {
mValues.clear();
}
/**
* Returns true if this object has the named value.
*
* @param key the value to check for
* @return {@code true} if the value is present, {@code false} otherwise
*/
//判断是否包含这个key，是则返回true否则false
public booleancontainsKey(String key) {
return mValues.containsKey(key);
}
/**
* Gets a value. Valid value types are {@link String}, {@linkBoolean}, and
* {@link Number} implementations.
*
* @param key the value to get
* @return the data for the value
*/
//获取一个值，值的类型是 字符串，布尔值和数字，作为对象返回
public Object get(String key) {
return mValues.get(key);
}
/**
* Gets a value and converts it to a String.
*
* @param key the value to get
* @return the String for the value
*/
//将获取的值转化为字符串返回
public String getAsString(String key) {
Object value = mValues.get(key);
returnvalue != null? value.toString() : null;
}
/**
* Gets a value and converts it to a Long.
*
* @param key the value to get
* @return the Long value, or null if the value is missing or cannot be converted
*/
public Long getAsLong(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).longValue() : null;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Long.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Long value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Long: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to an Integer.
*
* @param key the value to get
* @return the Integer value, or null if the value is missing or cannot be converted
*/
public Integer getAsInteger(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).intValue() : null;
} catch (ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Integer.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Integer value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Integer: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to a Short.
*
* @param key the value to get
* @return the Short value, or null if the value is missing or cannot be converted
*/
public Short getAsShort(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).shortValue() : null;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Short.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Short value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Short: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to a Byte.
*
* @param key the value to get
* @return the Byte value, or null if the value is missing or cannot be converted
*/
public Byte getAsByte(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).byteValue() : null;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Byte.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Byte value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Byte: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to a Double.
*
* @param key the value to get
* @return the Double value, or null if the value is missing or cannot be converted
*/
public Double getAsDouble(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).doubleValue() : null;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Double.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Double value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Double: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to a Float.
*
* @param key the value to get
* @return the Float value, or null if the value is missing or cannot be converted
*/
public Float getAsFloat(String key) {
Object value = mValues.get(key);
try{
returnvalue != null? ((Number) value).floatValue() : null;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
try {
return Float.valueOf(value.toString());
} catch (NumberFormatException e2) {
Log.e(TAG, "Cannotparse Float value for " + value + " at key " + key);
return null;
}
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Float: " + value, e);
return null;
}
}
}
/**
* Gets a value and converts it to a Boolean.
*
* @param key the value to get
* @return the Boolean value, or null if the value is missing or cannot be converted
*/
public Boolean getAsBoolean(String key) {
Object value = mValues.get(key);
try{
return(Boolean) value;
} catch(ClassCastException e) {
if(value instanceofCharSequence) {
return Boolean.valueOf(value.toString());
} else if (value instanceof Number) {
return ((Number) value).intValue() != 0;
} else{
Log.e(TAG, "Cannotcast value for " + key + " to a Boolean: " + value, e);
return null;
}
}
}
/**
* Gets a value that is a byte array. Note that this method will notconvert
* any other types to byte arrays.
*
* @param key the value to get
* @return the byte[] value, or null is the value is missing or not a byte[]
*/
public byte[]getAsByteArray(String key) {
Object value = mValues.get(key);
if(value instanceof byte[]) {
return(byte[]) value;
} else{
return null;
}
}
/**
* Returns a set of all of the keys and values
*
* @return a set of all of the keys and values
*/
public Set
return mValues.entrySet();
}
/**
* Returns a set of all of the keys
*
* @return a set of all of the keys
*/
public Set
return mValues.keySet();
}
public static final Parcelable.Creator
newParcelable.Creator
@SuppressWarnings({"deprecation", "unchecked"})
publicContentValues createFromParcel(Parcel in) {
// TODO - what ClassLoader should be passed toreadHashMap?
HashMap
return new ContentValues(values);
}
publicContentValues[] newArray(intsize) {
return new ContentValues[size];
}
};
public intdescribeContents() {
return0;
}
@SuppressWarnings("deprecation")
public voidwriteToParcel(Parcel parcel, intflags) {
parcel.writeMap(mValues);
}
/**
* Unsupported, here until we get proper bulk insert APIs.
* {@hide}
*/
@Deprecated
public void putStringArrayList(Stringkey, ArrayList
mValues.put(key,value);
}
/**
* Unsupported, here until we get proper bulk insert APIs.
* {@hide}
*/
@SuppressWarnings("unchecked")
@Deprecated
public ArrayListgetStringArrayList(Stringkey) {
return(ArrayList
}
/**
* Returns a string containing a concise, human-readable description of this object.
* @return a printable representation of this object.
*/
@Override
public String toString() {
StringBuilder sb = newStringBuilder();
for(String name : mValues.keySet()){
String value = getAsString(name);
if(sb.length() > 0) sb.append(" ");
sb.append(name + "="+ value);
}
returnsb.toString();
}
}