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BAEL2489 Avoid check for null statement in Java

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This commit is contained in:
Chirag Dewan 2019-03-19 20:40:26 +05:30
parent 55f7da4948
commit 66146ea761
8 changed files with 43 additions and 36 deletions
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7
core-java/src/main/java/com/baeldung/nulls/EmptyCollections.java
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@ -7,11 +7,12 @@ import java.util.stream.Stream;
public class EmptyCollections { public class EmptyCollections {
public List<String> names(){ public List<String> names() {
if (userExist()) if (userExist()) {
return Stream.of(readName()).collect(Collectors.toList()); return Stream.of(readName()).collect(Collectors.toList());
else } else {
return Collections.emptyList(); return Collections.emptyList();
}
} }
private boolean userExist() { private boolean userExist() {

5
core-java/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
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@ -16,10 +16,11 @@ public class FindBugsAnnotations {
@Nonnull @Nonnull
public Object process() throws Exception { public Object process() throws Exception {
Object result = doSomething(); Object result = doSomething();
if (result == null) if (result == null) {
throw new Exception("Processing fail. Got a null response"); throw new Exception("Processing fail. Got a null response");
else } else {
return result; return result;
}
} }
private Object doSomething() { private Object doSomething() {

18
core-java/src/main/java/com/baeldung/nulls/Preconditions.java
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@ -3,8 +3,9 @@ package com.baeldung.nulls;
public class Preconditions { public class Preconditions {
public void goodAccept(String one, String two, String three) { public void goodAccept(String one, String two, String three) {
if (one == null || two == null || three == null) if (one == null || two == null || three == null) {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
}
process(one); process(one);
process(two); process(two);
@ -12,20 +13,23 @@ public class Preconditions {
} }
public void badAccept(String one, String two, String three) { public void badAccept(String one, String two, String three) {
if (one == null) if (one == null) {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
else } else {
process(one); process(one);
}
if (two == null) if (two == null) {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
else } else {
process(two); process(two);
}
if (three == null) if (three == null) {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
else } else {
process(three); process(three);
}
} }

5
core-java/src/main/java/com/baeldung/nulls/PrimitivesAndWrapper.java
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@ -11,10 +11,11 @@ public class PrimitivesAndWrapper {
} }
public static Integer goodSum(Integer a, Integer b) { public static Integer goodSum(Integer a, Integer b) {
if (a != null && b != null) if (a != null && b != null) {
return a + b; return a + b;
else } else {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
}
} }
} }

11
core-java/src/main/java/com/baeldung/nulls/UsingObjects.java
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@ -4,13 +4,8 @@ import java.util.Objects;
public class UsingObjects { public class UsingObjects {
public void accept(Object param) throws Exception { public void accept(Object param) {
try { Objects.requireNonNull(param);
Objects.requireNonNull(param); // doSomething()
} catch (NullPointerException e) {
throw new Exception();
}
//doSomething()
} }
} }

8
core-java/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
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@ -8,7 +8,7 @@ import org.junit.jupiter.api.Test;
class PrimitivesAndWrapperUnitTest { class PrimitivesAndWrapperUnitTest {
@Test @Test
public void givenWrappers_whenBothArgsNonNull_thenReturnResult() { public void givenBothArgsNonNull_whenCallingWrapperSum_thenReturnSum() {
Integer sum = PrimitivesAndWrapper.wrapperSum(0, 0); Integer sum = PrimitivesAndWrapper.wrapperSum(0, 0);
@ -16,17 +16,17 @@ class PrimitivesAndWrapperUnitTest {
} }
@Test() @Test()
public void givenWrappers_whenOneArgIsNull_thenThrowNullPointerException() { public void givenOneArgIsNull_whenCallingWrapperSum_thenThrowNullPointerException() {
assertThrows(NullPointerException.class, () -> PrimitivesAndWrapper.wrapperSum(null, 2)); assertThrows(NullPointerException.class, () -> PrimitivesAndWrapper.wrapperSum(null, 2));
} }
@Test() @Test()
public void givenWrappers_whenBothArgsAreNull_thenThrowNullPointerException() { public void givenBothArgsNull_whenCallingWrapperSum_thenThrowNullPointerException() {
assertThrows(NullPointerException.class, () -> PrimitivesAndWrapper.wrapperSum(null, null)); assertThrows(NullPointerException.class, () -> PrimitivesAndWrapper.wrapperSum(null, null));
} }
@Test() @Test()
public void givenWrappersWithNullCheck_whenAnyArgIsNull_thenThrowIllegalArgumentException() { public void givenOneArgNull_whenCallingGoodSum_thenThrowIllegalArgumentException() {
assertThrows(IllegalArgumentException.class, () -> PrimitivesAndWrapper.goodSum(null, 2)); assertThrows(IllegalArgumentException.class, () -> PrimitivesAndWrapper.goodSum(null, 2));
} }

5
core-java/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
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@ -20,18 +20,23 @@ class UsingOptionalUnitTest {
@Test @Test
public void whenArgIsFalse_thenReturnEmptyResponse() { public void whenArgIsFalse_thenReturnEmptyResponse() {
Optional<Object> result = classUnderTest.process(false); Optional<Object> result = classUnderTest.process(false);
assertFalse(result.isPresent()); assertFalse(result.isPresent());
} }
@Test @Test
public void whenArgIsTrue_thenReturnValidResponse() { public void whenArgIsTrue_thenReturnValidResponse() {
Optional<Object> result = classUnderTest.process(true); Optional<Object> result = classUnderTest.process(true);
assertTrue(result.isPresent()); assertTrue(result.isPresent());
} }
@Test @Test
public void whenArgIsFalse_thenChainResponseAndThrowException() { public void whenArgIsFalse_thenChainResponseAndThrowException() {
assertThrows(Exception.class, () -> classUnderTest.process(false).orElseThrow(() -> new Exception())); assertThrows(Exception.class, () -> classUnderTest.process(false).orElseThrow(() -> new Exception()));
} }
} }

20
core-java/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
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@ -16,28 +16,28 @@ class UsingStringUtilsUnitTest {
} }
@Test @Test
public void givenAccept_whenArgIsNull_throwIllegalArgumentException() { public void givenArgIsNull_whenCallingAccept_throwIllegalArgumentException() {
Assertions.assertThrows(IllegalArgumentException.class, () -> classUnderTest.accept(null)); assertThrows(IllegalArgumentException.class, () -> classUnderTest.accept(null));
} }
@Test @Test
public void givenAccept_whenArgIsEmpty_throwIllegalArgumentException() { public void givenArgIsEmpty_whenCallingAccept_throwIllegalArgumentException() {
Assertions.assertThrows(IllegalArgumentException.class, () -> classUnderTest.accept("")); assertThrows(IllegalArgumentException.class, () -> classUnderTest.accept(""));
} }
@Test @Test
public void givenAcceptOnlyNonBlank_whenArgIsNull_throwIllegalArgumentException() { public void givenArgIsNull_whenCallingAcceptOnlyNonBlank_throwIllegalArgumentException() {
Assertions.assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank(null)); assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank(null));
} }
@Test @Test
public void givenAcceptOnlyNonBlank_whenArgIsEmpty_throwIllegalArgumentException() { public void givenArgIsEmpty_whenCallingAcceptOnlyNonBlank_throwIllegalArgumentException() {
Assertions.assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank("")); assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank(""));
} }
@Test @Test
public void givenAcceptOnlyNonBlank_whenArgIsBlank_throwIllegalArgumentException() { public void givenArgIsBlank_whenCallingAcceptOnlyNonBlank_throwIllegalArgumentException() {
Assertions.assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank(" ")); assertThrows(IllegalArgumentException.class, () -> classUnderTest.acceptOnlyNonBlank(" "));
} }
} }