BAEL2489 - Avoid check for null statement in Java (#6411)

* BAEL2489 - Avoid check for null statement in Java * BAEL2489 Avoid check for null statement in Java * BAEL2489 Avoid check for null statement in Java * BAEL2489 Avoid check for null statement in Java * BAEL2489 Avoid check for null statement in Java * BAEL2489 Avoid check for null statement in Java - Removing unused pom changes * BAEL2489 Avoid check for null statement in Java - Removing unused pom changes * Delete pom.xml Removing unused changes in core-java * BAEL2489 Avoid check for null statement in Java - Removing unused pom changes
2019-03-29 06:26:15 +05:30
parent 580ed9f626
commit 9687c88abf
16 changed files with 419 additions and 0 deletions
@@ -0,0 +1,30 @@
+package com.baeldung.nulls;
+
+public class APIContracts {
+
+    /**
+     * Prints the value of {@code param} if not null. Prints {@code null} otherwise.
+     *
+     * @param param
+     */
+    public void print(Object param) {
+        System.out.println("Printing " + param);
+    }
+
+    /**
+     * @return non null result
+     * @throws Exception - if result is null
+     */
+    public Object process() throws Exception {
+        Object result = doSomething();
+        if (result == null) {
+            throw new Exception("Processing fail. Got a null response");
+        } else {
+            return result;
+        }
+    }
+
+    private Object doSomething() {
+        return null;
+    }
+}
@@ -0,0 +1,13 @@
+package com.baeldung.nulls;
+
+public class Assertions {
+    
+    public void accept(Object param){
+        assert param != null;
+        
+        doSomething(param);
+    }
+
+    private void doSomething(Object param) {
+    }
+}
@@ -0,0 +1,25 @@
+package com.baeldung.nulls;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class EmptyCollections {
+
+    public List<String> names() {
+        if (userExist()) {
+            return Stream.of(readName()).collect(Collectors.toList());
+        } else {
+            return Collections.emptyList();
+        }
+    }
+
+    private boolean userExist() {
+        return false;
+    }
+
+    private String readName() {
+        return "test";
+    }
+}
@@ -0,0 +1,30 @@
+package com.baeldung.nulls;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+
+public class FindBugsAnnotations {
+
+    public void accept(@NotNull Object param) {
+        System.out.println(param.toString());
+    }
+
+    public void print(@Nullable Object param) {
+        System.out.println("Printing " + param);
+    }
+
+    @NotNull
+    public Object process() throws Exception {
+        Object result = doSomething();
+        if (result == null) {
+            throw new Exception("Processing fail. Got a null response");
+        } else {
+            return result;
+        }
+    }
+
+    private Object doSomething() {
+        return null;
+    }
+}
@@ -0,0 +1,39 @@
+package com.baeldung.nulls;
+
+public class Preconditions {
+
+    public void goodAccept(String one, String two, String three) {
+        if (one == null || two == null || three == null) {
+            throw new IllegalArgumentException();
+        }
+
+        process(one);
+        process(two);
+        process(three);
+    }
+
+    public void badAccept(String one, String two, String three) {
+        if (one == null) {
+            throw new IllegalArgumentException();
+        } else {
+            process(one);
+        }
+
+        if (two == null) {
+            throw new IllegalArgumentException();
+        } else {
+            process(two);
+        }
+
+        if (three == null) {
+            throw new IllegalArgumentException();
+        } else {
+            process(three);
+        }
+
+    }
+
+    private void process(String one) {
+    }
+
+}
@@ -0,0 +1,21 @@
+package com.baeldung.nulls;
+
+public class PrimitivesAndWrapper {
+
+    public static int primitiveSum(int a, int b) {
+        return a + b;
+    }
+
+    public static Integer wrapperSum(Integer a, Integer b) {
+        return a + b;
+    }
+
+    public static Integer goodSum(Integer a, Integer b) {
+        if (a != null && b != null) {
+            return a + b;
+        } else {
+            throw new IllegalArgumentException();
+        }
+    }
+
+}
@@ -0,0 +1,10 @@
+package com.baeldung.nulls;
+
+import lombok.NonNull;
+
+public class UsingLombok {
+
+    public void accept(@NonNull Object param){
+        System.out.println(param);
+    }
+}
@@ -0,0 +1,11 @@
+package com.baeldung.nulls;
+
+import java.util.Objects;
+
+public class UsingObjects {
+
+    public void accept(Object param) {
+        Objects.requireNonNull(param);
+        // doSomething()
+    }
+}
@@ -0,0 +1,27 @@
+package com.baeldung.nulls;
+
+import java.util.Optional;
+
+public class UsingOptional {
+
+    public Optional<Object> process(boolean processed) {
+
+        String response = doSomething(processed);
+
+        if (response == null) {
+            return Optional.empty();
+        }
+
+        return Optional.of(response);
+    }
+
+    private String doSomething(boolean processed) {
+
+        if (processed) {
+            return "passed";
+        } else {
+            return null;
+        }
+    }
+
+}
@@ -0,0 +1,22 @@
+package com.baeldung.nulls;
+
+import org.apache.commons.lang3.StringUtils;
+
+public class UsingStringUtils {
+
+    public void accept(String param) {
+        if (StringUtils.isNotEmpty(param)) {
+            System.out.println(param);
+        } else {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public void acceptOnlyNonBlank(String param) {
+        if (StringUtils.isNotBlank(param)) {
+            System.out.println(param);
+        } else {
+            throw new IllegalArgumentException();
+        }
+    }
+}