Groovy example source code file (ClosureJavaIntegrationTest.java)

This example Groovy source code file (ClosureJavaIntegrationTest.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

arraylist, boolean, closure, closure, giraffe, integer, integer, lions, lions, list, list, map, math, monkeys, string, util

The Groovy ClosureJavaIntegrationTest.java source code

/*
 * Copyright 2003-2011 the original author or authors.
 *
 * 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 groovy;

import groovy.lang.Closure;
import groovy.lang.Reference;
import junit.framework.TestCase;
import org.codehaus.groovy.runtime.DefaultGroovyMethods;
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static org.codehaus.groovy.runtime.DefaultGroovyMethods.*;

/**
 * Groovy's Closure class isn't specifically designed with Java integration in
 * mind, but these tests illustrate some of the possible ways to use them from Java.
 */
public class ClosureJavaIntegrationTest extends TestCase {
    Map<String, Integer> zoo = new HashMap();
    List<String> animals = Arrays.asList("ant", "bear", "camel");

    @Override
    protected void setUp() throws Exception {
        super.setUp();
        zoo.put("Monkeys", 3);
        zoo.put("Giraffe", 2);
        zoo.put("Lions", 5);
    }

    public void testJoinListNonClosureCase() {
        assertEquals(join(animals, ", "), "ant, bear, camel");
    }

    public void testEachList() {
        final List<Integer> result = new ArrayList();
        each(animals, new Closure(null) {
            public void doCall(String arg) {
                result.add(arg.length());
            }
        });
        assertEquals(Arrays.asList(3, 4, 5), result);
    }

    public void testEachMap() {
        final List<String> result = new ArrayList();
        each(zoo, new Closure(null) {
            public void doCall(String k, Integer v) {
                result.add("k=" + k + ",v=" + v);
            }
        });
        assertEquals(Arrays.asList("k=Lions,v=5", "k=Monkeys,v=3", "k=Giraffe,v=2"), result);
    }

    public void testCollectList() {
        assertEquals(Arrays.asList(3, 4, 5), collect(animals, new Closure<Integer>(null) {
            public Integer doCall(String it) {
                return it.length();
            }
        }));
    }

    public void testMaxMap() {
        Map.Entry<String, Integer> lionEntry = null;
        for (Map.Entry<String, Integer> entry : zoo.entrySet()) {
            if (entry.getKey().equals("Lions")) lionEntry = entry;
        }
        assertEquals(lionEntry, max(zoo.entrySet(), new Closure<Integer>(null) {
            public Integer doCall(Map.Entry<String, Integer> e) {
                return e.getKey().length() * e.getValue();
            }
        }));
    }

    public void testSortMapKeys() {
        assertEquals(Arrays.asList("Monkeys", "Lions", "Giraffe"), sort(zoo.keySet(), new Closure<Integer>(null) {
            public Integer doCall(String a, String b) {
                return -a.compareTo(b);
            }
        }));
        assertEquals(Arrays.asList("Giraffe", "Lions", "Monkeys"), sort(zoo.keySet(), new Closure<Integer>(null) {
            public Integer doCall(String a, String b) {
                return a.compareTo(b);
            }
        }));
    }

    public void testAnyMap() {
        assertTrue(any(zoo, new Closure<Boolean>(null) {
            public Boolean doCall(String k, Integer v) {
                return k.equals("Lions") && v == 5;
            }
        }));
    }

    public void testFindAllAndCurry() {
        Map<String, Integer> expected = new HashMap(zoo);
        expected.remove("Lions");
        Closure<Boolean> keyBiggerThan = new Closure(null) {
            public Boolean doCall(Map.Entry<String, Integer> e, Integer size) {
                return e.getKey().length() > size;
            }
        };
        Closure<Boolean> keyBiggerThan6 = keyBiggerThan.rcurry(6);
        assertEquals(expected, findAll(zoo, keyBiggerThan6));
    }

    public void testListArithmetic() {
        List<List> numLists = new ArrayList();
        numLists.add(Arrays.asList(1, 2, 3));
        numLists.add(Arrays.asList(10, 20, 30));
        assertEquals(Arrays.asList(6, 60), collect(numLists, new Closure<Integer>(null) {
            public Integer doCall(Integer a, Integer b, Integer c) {
                return a + b + c;
            }
        }));
        Closure<Integer> arithmeticClosure = new Closure(null) {
            public Integer doCall(Integer a, Integer b, Integer c) {
                return a * b + c;
            }
        };
        Closure<Integer> tensAndUnits = arithmeticClosure.curry(10);
        assertEquals(35, (int) tensAndUnits.call(3, 5));
        tensAndUnits = arithmeticClosure.ncurry(0, 10);
        assertEquals(35, (int) tensAndUnits.call(3, 5));
        tensAndUnits = arithmeticClosure.ncurry(1, 10);
        assertEquals(35, (int) tensAndUnits.call(3, 5));
        Closure<Integer> timesPlus5 = arithmeticClosure.rcurry(5);
        assertEquals(35, (int) timesPlus5.call(15, 2));
        timesPlus5 = arithmeticClosure.ncurry(2, 5);
        assertEquals(35, (int) timesPlus5.call(15, 2));
    }

    public void testComposition() {
        Closure<String> toUpperCase = new Closure(null) {
            public String doCall(String s) {
                return s.toUpperCase();
            }
        };
        Closure<Boolean> hasCapitalA = new Closure(null) {
            public Boolean doCall(String s) {
                return s.contains("A");
            }
        };
        Closure<Boolean> hasA = toUpperCase.rightShift(hasCapitalA);
        assertTrue(every(animals, hasA));
        Closure<Boolean> alsoHasA = hasCapitalA.leftShift(toUpperCase);
        assertTrue(every(animals, alsoHasA));
    }

    public void testTrampoline() {
        final Reference<Closure ref = new Reference>();
        ref.set(new Closure<BigInteger>(null) {
            public Object doCall(Integer n, BigInteger total) {
                return n > 1 ? ref.get().trampoline(n - 1, total.multiply(BigInteger.valueOf(n))) : total;
            }
        }.trampoline());
        Closure<BigInteger> factorial = new Closure(null) {
            public BigInteger doCall(Integer n) {
                return ref.get().call(n, BigInteger.ONE);
            }
        };
        assertEquals(BigInteger.valueOf(479001600), factorial.call(12));
    }

    public void testInject() {
        Collection<Integer> c = Arrays.asList(2, 4, 5, 20);
        Number initial = BigDecimal.ZERO;
        Closure<? extends Number> closure = new Closure(c) {
            BigDecimal doCall(BigDecimal total, Integer next) {
                return total.add(BigDecimal.ONE.divide(new BigDecimal(next)));
            }
        };
        assertTrue(DefaultTypeTransformation.compareEqual(BigDecimal.ONE, inject(c, initial, closure)));
    }
}