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Added partition operators.
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‎src/main/java/com/drunkendev/lambdas/PartitioningOperators.java

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/*
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* PartitioningOperators.java Feb 3 2014, 03:44
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*
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* Copyright 2014 Drunken Dev.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.drunkendev.lambdas;
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import com.drunkendev.lambdas.domain.DomainService;
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import com.drunkendev.lambdas.domain.Order;
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import com.drunkendev.lambdas.helper.IndexHolder;
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import com.drunkendev.lambdas.helper.MutableBoolean;
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import java.util.ArrayList;
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import java.util.Arrays;
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/**
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*
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* @author Brett Ryan
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*/
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public class PartitioningOperators {
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private final DomainService ds;
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/**
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* Creates a new {@code PartitioningOperators} instance.
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*/
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public PartitioningOperators() {
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this.ds = new DomainService();
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}
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public static void main(String[] args) {
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PartitioningOperators po = new PartitioningOperators();
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po.lambda20();
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po.lambda21();
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po.lambda22();
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po.lambda23();
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po.lambda24();
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po.lambda25();
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po.lambda26();
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po.lambda27();
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}
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public void lambda20() {
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System.out.println("\nFirst 3 numbers:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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Arrays.stream(numbers)
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.limit(3)
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.forEach(System.out::println);
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}
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public void lambda21() {
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System.out.println("\nFirst 3 orders in WA:");
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ds.getCustomerList().stream()
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.filter(c -> "WA".equalsIgnoreCase(c.getRegion()))
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.flatMap(c -> c.getOrders().stream()
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.map(n -> new CustOrder(c.getCustomerId(), n))
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).limit(3)
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.forEach(System.out::println);
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}
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public void lambda22() {
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System.out.println("\nAll but first 4 numbers:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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Arrays.stream(numbers)
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.skip(4)
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.forEach(System.out::println);
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}
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public void lambda23() {
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System.out.println("\nAll but first 2 orders in WA:");
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ds.getCustomerList().stream()
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.filter(c -> "WA".equalsIgnoreCase(c.getRegion()))
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.flatMap(c -> c.getOrders().stream()
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.map(n -> new CustOrder(c.getCustomerId(), n))
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).skip(2)
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.forEach(System.out::println);
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}
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/**
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* Unfortunately this method will not short circuit and will continue to
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* iterate until the end of the stream. I need to figure out a better way to
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* handle this.
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*/
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public void lambda24() {
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System.out.println("\nFirst numbers less than 6:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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MutableBoolean mb = new MutableBoolean(true);
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Arrays.stream(numbers)
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.collect(ArrayList<Integer>::new,
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(output, v) -> {
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if (mb.isTrue()) {
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if (v < 6) {
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output.add(v);
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} else {
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mb.flip();
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}
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}
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},
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(c1, c2) -> c1.addAll(c2))
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.forEach(System.out::println);
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}
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public void lambda25() {
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System.out.println("\nFirst numbers not less than their position:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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IndexHolder i = new IndexHolder();
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MutableBoolean mb = new MutableBoolean(true);
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Arrays.stream(numbers)
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.collect(ArrayList<Integer>::new,
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(output, v) -> {
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if (mb.isTrue()) {
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if (v > i.postIncrement()) {
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output.add(v);
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} else {
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mb.flip();
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}
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}
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},
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(c1, c2) -> c1.addAll(c2))
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.forEach(System.out::println);
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}
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public void lambda26() {
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System.out.println("\nAll elements starting from first element divisible by 3:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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MutableBoolean mb = new MutableBoolean(false);
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Arrays.stream(numbers)
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.collect(ArrayList<Integer>::new,
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(output, v) -> {
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if (mb.isTrue()) {
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output.add(v);
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} else if (v % 3 == 0) {
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output.add(v);
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mb.flip();
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}
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},
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(c1, c2) -> c1.addAll(c2))
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.forEach(System.out::println);
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}
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public void lambda27() {
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System.out.println("\nAll elements starting from first element less than its position:");
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int[] numbers = {5, 4, 1, 3, 9, 8, 6, 7, 2, 0};
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IndexHolder i = new IndexHolder();
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MutableBoolean mb = new MutableBoolean(false);
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Arrays.stream(numbers)
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.collect(ArrayList<Integer>::new,
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(output, v) -> {
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if (mb.isTrue()) {
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output.add(v);
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} else if (v < i.postIncrement()) {
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output.add(v);
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mb.flip();
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}
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},
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(c1, c2) -> c1.addAll(c2)
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)
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.forEach(System.out::println);
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}
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private static class CustOrder {
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private final String customerId;
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private final Order order;
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public CustOrder(String customerId, Order order) {
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this.customerId = customerId;
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this.order = order;
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}
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public String getCustomerId() {
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return customerId;
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}
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public Order getOrder() {
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return order;
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}
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@Override
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public String toString() {
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return String.format("CustOrder[customerId=%s,orderId=%d,orderDate=%s]",
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customerId, order.getOrderId(), order.getOrderDate());
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}
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}
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}

‎src/main/java/com/drunkendev/lambdas/helper/MutableBoolean.java

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/*
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* MutableBoolean.java Feb 3 2014, 04:36
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*
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* Copyright 2014 Drunken Dev.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.drunkendev.lambdas.helper;
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/**
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*
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* @author Brett Ryan
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*/
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public class MutableBoolean {
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private boolean value;
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/**
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* Creates a new {@code MutableBoolean} instance.
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*/
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public MutableBoolean() {
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this(false);
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}
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public MutableBoolean(boolean value) {
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this.value = value;
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}
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public boolean getValue() {
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return value;
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}
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public void setValue(boolean value) {
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this.value = value;
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}
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public boolean isTrue() {
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return value;
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}
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public void flip() {
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this.value = !this.value;
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}
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}

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