Java 8 bean comparison static method using lambdas of getters to specify which properties to compare

BeanCompareUtil.java

package com.nileshk;

import java.util.function.Function;
import java.util.stream.Stream;

public class BeanCompareUtil {

	public static <T> boolean compareBeans(T bean1, T bean2, Function<T, Object>... getters) {
		return Stream.of(getters).allMatch(getter -> {
			Object val1 = getter.apply(bean1);
			Object val2 = getter.apply(bean2);
			return (val1 == null && val2 == null) ||
					(val1 != null && val1.equals(val2));
		});
	}

}

BeanCompareUtilTest.java

package com.nileshk;

import org.junit.Test;

import java.math.BigDecimal;

import static com.nileshk.BeanCompareUtil.compareBeans;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

public class BeanCompareUtilTest {

	@Test
	public void testCompareBeansTrue() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_subsetOfGetters() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_nullString() {
		BeanToTest bean1 = new BeanToTest("SomeString1", null, 0, 0.0, false);
		BeanToTest bean2 = new BeanToTest("SomeString1", null, 0, 0.0, false);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_nullInteger() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", null, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", null, 123.45, true);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_nullDouble() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", 128, null, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", 128, null, true);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_nullBoolean() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", 128, 3.14, null);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", 128, 3.14, null);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansTrue_allNulls() {
		BeanToTest bean1 = new BeanToTest(null, null, null, null, null);
		BeanToTest bean2 = new BeanToTest(null, null, null, null, null);
		assertTrue(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansFalse_string() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString3", 256, 123.45, true);
		assertFalse(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansFalse_stringNullFirst() {
		BeanToTest bean1 = new BeanToTest("SomeString1", null, 256, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", "AnotherString2", 256, 123.45, true);
		assertFalse(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	@Test
	public void testCompareBeansFalse_stringNullSecond() {
		BeanToTest bean1 = new BeanToTest("SomeString1", "AnotherString", 256, 123.45, true);
		BeanToTest bean2 = new BeanToTest("SomeString1", null, 256, 123.45, true);
		assertFalse(compareBeans(bean1, bean2,
				BeanToTest::getSomeString,
				BeanToTest::getAnotherString,
				BeanToTest::getSomeInteger,
				BeanToTest::getSomeDouble,
				BeanToTest::getSomeBoolean
		));
	}

	protected class BeanToTest {

		private String someString;
		private String anotherString;
		private Integer someInteger;
		private Double someDouble;
		private Boolean someBoolean;

		public BeanToTest(String someString, String anotherString, Integer someInteger, Double someDouble, Boolean someBoolean) {
			this.someString = someString;
			this.anotherString = anotherString;
			this.someInteger = someInteger;
			this.someDouble = someDouble;
			this.someBoolean = someBoolean;
		}

		public String getSomeString() {
			return someString;
		}

		public void setSomeString(String someString) {
			this.someString = someString;
		}

		public String getAnotherString() {
			return anotherString;
		}

		public void setAnotherString(String anotherString) {
			this.anotherString = anotherString;
		}

		public Integer getSomeInteger() {
			return someInteger;
		}

		public void setSomeInteger(Integer someInteger) {
			this.someInteger = someInteger;
		}

		public Double getSomeDouble() {
			return someDouble;
		}

		public void setSomeDouble(Double someDouble) {
			this.someDouble = someDouble;
		}

		public Boolean getSomeBoolean() {
			return someBoolean;
		}

		public void setSomeBoolean(Boolean someBoolean) {
			this.someBoolean = someBoolean;
		}
	}

}