Completely reworked the tests

src/test/resources/java/BestPractices.java

@@ -0,0 +1,50 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;/**
+ * BestPractices class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class BestPractices {
+    private final String ip = "127.0.0.1";     // not recommended
+    private StringBuffer buffer;    // potential memory leak as an instance variable;
+    private String[] x;
+
+    void bar(int a) {
+        switch (a) {
+            case 1:  // do something
+                break;
+            default:  // the default case should be last, by convention
+                break;
+            case 2:
+                break;
+        }
+    }
+
+    public void foo(String[] param) {
+        // Don't do this, make a copy of the array at least
+        this.x = param;
+    }
+
+    private void greet(String name) {
+        name = name.trim();
+        System.out.println("Hello " + name);
+    }
+
+
+}

src/test/resources/java/CodeStyle.java

@@ -0,0 +1,46 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;
+
+/**
+ * CodeStyle class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public final class CodeStyle {
+    final int FinalField = 1;
+    private int x;
+    private int y;  // class cannot be subclassed, so is y really private or package visible?
+
+    // missing constructor
+
+    boolean bar(int x, int y) {
+        try {
+            x = y;
+        } catch (IllegalArgumentException e) {
+            throw e;
+        } catch (IllegalStateException e) { // Can be collapsed into the previous block
+            throw e;
+        }
+
+        if (true) ; // empty if statement
+        if (true) { // empty as well
+        }
+        return x == y;
+    }
+}

src/test/resources/java/Design.java

@@ -0,0 +1,40 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;/**
+ * Design class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class Design {
+    String field;
+    int otherField;
+
+    void foo() {
+        throw new NullPointerException();
+    }
+
+    public void bar(int x, int y, int z) {
+        if (x > y) {
+            if (y > z) {
+                if (z == x) {
+                    // !! too deep
+                }
+            }
+        }
+    }
+}

src/test/resources/java/Documentation.java

@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;/**
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class Documentation {
+    public Documentation() {
+        // This constructor is intentionally empty. Nothing special is needed here.
+    }
+
+    public void doSomething() {
+    }
+}

src/test/resources/java/ErrorProne.java

@@ -0,0 +1,52 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;/**
+ * ErrorProne class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class ErrorProne {
+    static int x;
+
+    public ErrorProne(int y) {
+        x = y; // unsafe
+
+        // unusual use of branching statement in a loop
+        for (int i = 0; i < 10; i++) {
+            if (i * i <= 25) {
+                continue;
+            }
+            break;
+        }
+    }
+
+    void foo() {
+        try {
+            // do something
+        } catch (Throwable th) {  // should not catch Throwable
+            th.printStackTrace();
+        }
+    }
+
+    void bar() {
+        try {
+            // do something
+        } catch (NullPointerException npe) {
+        }
+    }
+}

src/test/resources/java/MultiThreading.java

@@ -0,0 +1,50 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;import java.text.SimpleDateFormat;
+
+/**
+ * MultiThreading class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class MultiThreading {
+    private static final SimpleDateFormat sdf = new SimpleDateFormat();
+    /*volatile */ Object baz = null; // fix for Java5 and later: volatile
+    private volatile String var1; // not suggested
+
+    void bar() {
+        sdf.format("bar"); // poor, no thread-safety
+    }
+
+    void foo() {
+        synchronized (sdf) { // preferred
+            sdf.format("foo");
+        }
+    }
+
+    Object obj() {
+        if (baz == null) { // baz may be non-null yet not fully created
+            synchronized (this) {
+                if (baz == null) {
+                    baz = new Object();
+                }
+            }
+        }
+        return baz;
+    }
+}

src/test/resources/java/Performance.java

@@ -0,0 +1,55 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;/**
+ * Performance class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class Performance {
+    public static void main(String[] as) {
+        for (int i = 0; i < 10; i++) {
+            Performance p = new Performance(); // Avoid this whenever you can it's really expensive
+        }
+    }
+
+
+    private boolean checkTrimEmpty(String str) {
+        for (int i = 0; i < str.length(); i++) {
+            if (!Character.isWhitespace(str.charAt(i))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    void foo() {
+        StringBuffer sb = new StringBuffer();
+        sb.append("a");     // avoid this
+
+        String foo = " ";
+        StringBuffer buf = new StringBuffer();
+        buf.append("Hello"); // poor
+        buf.append(foo);
+        buf.append("World");
+
+        buf.append("Hello").append(" ").append("World");
+
+        StringBuffer sbuf = new StringBuffer("tmp = " + System.getProperty("java.io.tmpdir"));
+// poor
+    }
+}

src/test/resources/java/Security.java

@@ -0,0 +1,34 @@
+/*
+ *  Copyright 2023 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
+ *
+ *       https://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 java;import java.security.SecureRandom;
+
+/**
+ * Security class
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public class Security {
+    void bad() {
+        byte[] iv = new byte[] { 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, };
+    }
+
+    void alsoBad() {
+        byte[] iv = "secret iv in here".getBytes();
+    }
+
+}