当可选值为空时如何返回？

我喜欢现在Java标准库中的可选选项。但是有一个基本问题我一直遇到，我还没有想出如何以最好的方式解决（最容易阅读和理解，最漂亮，最短）：

当可选值为空时，如何从方法返回？

我正在寻找一种通用解决方案，适用于可选数量和代码块大小的不同组合。

在以下示例中，我将尝试显示我的意思：

void m1() {
    // When I get an optional:
    Optional<String> o = getOptional();

    // And want to return if it's empty
    if (!o.isPresent()) return;
    
    // In the whole rest of the method I have to call Optional.get 
    // every time I want the value:
    System.out.println(o.get());
    
    // Which is pretty ugly and verbose!
}


void m2() {
    // If I instead return null if a value is absent:
    String s = getNullabe();
    if (s == null) return;
    
    // Then I can use the value directly:
    System.out.println(s);
}

这个问题是关于如何获得上述两个示例的良好方面：可选类型的安全类型和可空类型的简洁性。

其余示例对此进行了更多说明。

void m3() {
    // If I on the other hand want to throw on empty that's pretty and compact:
    String s = getOptional()
        .orElseThrow(IllegalStateException::new);
    
    System.out.println(s);
}

void m4() {
    Optional<String> o = getOptional();
    if (!o.isPresent()) return;
    
    // I can of course declare a new variable for the un-optionalised string:
    String s = o.get();

    System.out.println(s);
    
    // But the old variable still remains in scope for the whole method 
    // which is ugly and annoying.
    System.out.println(o.get());
}


void m5() {
    // This is compact and maybe pretty in some ways:
    getOptional().ifPresent(s -> {
        System.out.println(s);

        // But the extra level of nesting is annoying and it feels 
        // wrong to write all the code in a big lambda.
        
        getOtherOptional().ifPresent(i -> {
            // Also, more optional values makes it really weird and 
            // pretty hard to read,  while with nullables I would 
            // get no extra nesting, it would looks good and be 
            // easy to read.
            System.out.println("i: " + i);
            
            // It doesn't work in all cases either way.
        });
    });
}


Optional<String> getOptional() {
    throw new UnsupportedOperationException();
}

Optional<Integer> getOtherOptional() {
    throw new UnsupportedOperationException();
}

String getNullabe() {
    throw new UnsupportedOperationException();
}

如果可选值为空，我该如何从方法返回，而不必在方法的其余部分使用，而无需声明额外的变量，也没有额外的块嵌套级别？get

或者，如果不可能获得所有这些，那么处理这种情况的最佳方法是什么？