org.apache.juneau.internal.ListBuilder Maven / Gradle / Ivy
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// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file *
// * distributed with this work for additional information regarding copyright ownership. The ASF licenses this file *
// * to you 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 org.apache.juneau.internal;
import static org.apache.juneau.common.internal.StringUtils.*;
import static org.apache.juneau.common.internal.ThrowableUtils.*;
import static org.apache.juneau.internal.ConverterUtils.*;
import static java.util.Collections.*;
import java.lang.reflect.*;
import java.util.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.parser.*;
/**
* Builder for lists.
*
* See Also:
*
*
* @param Element type.
*/
public final class ListBuilder {
//-----------------------------------------------------------------------------------------------------------------
// Static
//-----------------------------------------------------------------------------------------------------------------
/**
* Static creator.
*
* @param The element type.
* @param elementType The element type.
* @param elementTypeArgs Optional element type arguments.
* @return A new builder.
*/
public static ListBuilder create(Class elementType, Type...elementTypeArgs) {
return new ListBuilder<>(elementType, elementTypeArgs);
}
//-----------------------------------------------------------------------------------------------------------------
// Instance
//-----------------------------------------------------------------------------------------------------------------
private List list;
private boolean unmodifiable = false, sparse = false;
private Comparator comparator;
private Class elementType;
private Type[] elementTypeArgs;
/**
* Constructor.
*
* @param elementType The element type.
* @param elementTypeArgs The element type generic arguments if there are any.
*/
public ListBuilder(Class elementType, Type...elementTypeArgs) {
this.elementType = elementType;
this.elementTypeArgs = elementTypeArgs;
}
/**
* Constructor.
*
* @param addTo The list to add to.
*/
public ListBuilder(List addTo) {
this.list = addTo;
}
/**
* Builds the list.
*
* @return A list conforming to the settings on this builder.
*/
public List build() {
if (sparse) {
if (list != null && list.isEmpty())
list = null;
} else {
if (list == null)
list = new ArrayList<>(0);
}
if (list != null) {
if (comparator != null)
Collections.sort(list, comparator);
if (unmodifiable)
list = unmodifiableList(list);
}
return list;
}
/**
* When specified, the {@link #build()} method will return null if the list is empty.
*
*
* Otherwise {@link #build()} will never return null .
*
* @return This object.
*/
public ListBuilder sparse() {
this.sparse = true;
return this;
}
/**
* When specified, {@link #build()} will return an unmodifiable list.
*
* @return This object.
*/
public ListBuilder unmodifiable() {
this.unmodifiable = true;
return this;
}
/**
* Forces the existing list to be copied instead of appended to.
*
* @return This object.
*/
public ListBuilder copy() {
if (list != null)
list = new ArrayList<>(list);
return this;
}
/**
* Sorts the contents of the list.
*
* @return This object.
*/
@SuppressWarnings("unchecked")
public ListBuilder sorted() {
return sorted((Comparator)Comparator.naturalOrder());
}
/**
* Sorts the contents of the list using the specified comparator.
*
* @param comparator The comparator to use for sorting.
* @return This object.
*/
public ListBuilder sorted(Comparator comparator) {
this.comparator = comparator;
return this;
}
/**
* Appends the contents of the specified collection into this list.
*
*
* This is a no-op if the value is null .
*
* @param value The collection to add to this list.
* @return This object.
*/
public ListBuilder addAll(Collection value) {
if (value != null) {
if (list == null)
list = new LinkedList<>(value);
else
list.addAll(value);
}
return this;
}
/**
* Adds a single value to this list.
*
* @param value The value to add to this list.
* @return This object.
*/
public ListBuilder add(E value) {
if (list == null)
list = new ArrayList<>();
list.add(value);
return this;
}
/**
* Adds multiple values to this list.
*
* @param values The values to add to this list.
* @return This object.
*/
@SuppressWarnings("unchecked")
public ListBuilder add(E...values) {
for (E v : values)
add(v);
return this;
}
/**
* Adds entries to this list via JSON array strings.
*
* @param values The JSON array strings to parse and add to this list.
* @return This object.
*/
public ListBuilder addJson(String...values) {
return addAny((Object[])values);
}
/**
* Adds arbitrary values to this list.
*
*
* Objects can be any of the following:
*
* - The same type or convertible to the element type of this list.
*
- Collections or arrays of anything on this list.
*
- JSON array strings parsed and convertible to the element type of this list.
*
*
* @param values The values to add.
* @return This object.
*/
public ListBuilder addAny(Object... values) {
if (elementType == null)
throw new IllegalStateException("Unknown element type. Cannot use this method.");
try {
if (values != null) {
for (Object o : values) {
if (o != null) {
if (o instanceof Collection) {
((Collection)o).forEach(x -> addAny(x));
} else if (o.getClass().isArray()) {
for (int i = 0; i < Array.getLength(o); i++)
addAny(Array.get(o, i));
} else if (isJsonArray(o, false)) {
new JsonList(o.toString()).forEach(x -> addAny(x));
} else if (elementType.isInstance(o)) {
add(elementType.cast(o));
} else {
add(toType(o, elementType, elementTypeArgs));
}
}
}
}
} catch (ParseException e) {
throw asRuntimeException(e);
}
return this;
}
/**
* Appends a value to this list of the flag is true.
*
* @param flag The flag.
* @param value The value.
* @return This object.
*/
public ListBuilder addIf(boolean flag, E value) {
if (flag)
add(value);
return this;
}
}