IDEA Maven 配置问题合集 source value * is obsolete

build failed: source value * is obsolete and will be removed in a future release

这其实只是一个警告，但是这意味着有些新特性、新版本的问题可能是由于源码编译版本导致。
该问题具体的低层原因不详，直接原因是Java Compiler 字节码版本太低。
解决方案：
  Settings -> Build, Execution, Deployement -> Compiler -> Java Compiler -> Module Target bytecode version，将此处目标字节码版本提升到合适的版本。比如说这里设为1.7时会出现JUnit5单元测试构建失败。改为11或17后通过。
参考自Removing warning messages on IntelliJ IDEA while building Java project

警告示例：

Warning:java: source value 1.5 is obsolete and will be removed in a future release
Warning:java: source value 7 is obsolete and will be removed in a future release

具体场景是JUnit5单元测试构建失败，因此过不去。
代码附下，这里面其实只有一个位置会因为字节码版本过不去，原因可能是编译过程的字节码优化导致的。

public class Evaluate {
    public static void main(String[] args) {
        Deque ops = new ArrayDeque<>();
        Deque vals = new ArrayDeque<>();
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String s = scanner.next();
            switch (s) {
                case "(":break;
                case "+":
                case "-":
                case "*":
                case "/":
                case "sqrt":
                    ops.push(s);
                    break;
                case ")":
                    String op = ops.pop();
                    double v = vals.pop();
                    switch (op) {
                        case "+":
                            v = vals.pop() + v;
                            break;
                        case "-":
                            v = vals.pop() - v;
                            break;
                        case "*":
                            v = vals.pop() * v;
                            break;
                        case "/":
                            v = vals.pop() / v;
                            break;
                        case "sqrt":
                            v = Math.sqrt(v);
                    }
                    vals.push(v);
                    break;
                default:
                    vals.push(Double.parseDouble(s));
            }
        }
        System.out.println(vals.pop());
    }
}

public class EvaluateTest {
    @Test
    public void test() {
        try {
            String input = "( 1 + ( ( 2 + 3 ) * ( 4 * 5 ) ) )";
            Scanner scanner = new IOProxy(
                    "ch1.sec2.Evaluate",
                    "main",
                    String[].class
            ).invoke(input, (Object) null);
            assertEquals(scanner.nextDouble(), 101.0);

            input = "( ( 1 + sqrt ( 5.0 ) ) / 2.0 )";
            scanner = new IOProxy(
                    "ch1.sec2.Evaluate",
                    "main",
                    String[].class
            ).invoke(input, (Object) null);
            // 下面这一行会过不去
            assertEquals(scanner.nextDouble(), 1.618, 0.1);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public class IOProxy {
    private Class targetClass;
    private Method method;

    public IOProxy(String className, String methodName, Class... parameterTypes)
            throws ClassNotFoundException, NoSuchMethodException {
        targetClass = Class.forName(className);
        method = targetClass.getMethod(methodName, parameterTypes);
    }

    private Scanner invoke(InputStream is, Object... args)
            throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
        InputStream sin = System.in;
        PrintStream sout = System.out;
        System.setIn(is);
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        System.setOut(new PrintStream(os));
        method.invoke(targetClass.getDeclaredConstructor().newInstance(), args);
        System.setIn(sin);
        System.setOut(sout);
        return new Scanner(new ByteArrayInputStream(os.toByteArray()));
    }

    public Scanner invoke(String input, Object... args)
            throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
        return invoke(new ByteArrayInputStream(input.getBytes()), args);
    }

    public Scanner invoke(File input, Object... args)
            throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, FileNotFoundException {
        return invoke(new FileInputStream(input), args);
    }
}