连接不同的流并在 Java 上打印

Question

我正在尝试打印包含 String 和 Integer 元素的 concat Stream。我尝试了几种方法，但其中 none 行得通。我在互联网上找不到合适的方法。如您所见，这只是一个测试代码：

import java.util.stream.*;
class testconcat{
    public static void main(String[] args){
        Stream<String> part1=Stream.of("Testing the ");
        Stream<String> part2=Stream.of("streams concat");
        Stream<String> part3=Stream.of(" on Java, dividing ");
        Stream<String> part4=Stream.of("this phrase in ");
        IntStream part5=IntStream.of(6);
        Stream<String> part6=Stream.of(" parts.");

        String phrase=Stream.concat(Stream.concat(Stream.concat(Stream.concat(Stream.concat(part1, part2), part3), part4), part5), part6);
        System.out.println(phrase);
    }
}

我知道第 5 部分是一个整数，所以我不能以常规方式连接它，所以我也试过了：

        IntStream part5=IntStream.of(6);
        Stream<String> part6=Stream.of(" parts.");

        String phrase=Stream.concat(IntStream.concat(Stream.concat(Stream.concat(Stream.concat(part1, part2), part3), part4), part5), part6);
        System.out.println(phrase);
    }
}

还有：

        Integer part5=6;
        String part6=(" parts.");

        String phrase=Stream.concat(Stream.concat(Stream.concat(Stream.concat(Stream.concat(part1, part2), part3), part4);
        System.out.println(phrase + Integer.toString(part5) + part6);
    }
}

None 其中有效。有没有办法做到这一点？提前致谢。

Answer 1

如果我理解正确并且你想创建一个组合流字符串，你可以使用类似的东西：

Stream.concat(...):

Stream<Integer> integerStream = IntStream.range(72, 129).boxed(); // to convert to Stream<Integer>
Stream<String> stringStream =Stream.of(" String Stream");
String str = Stream.concat(integerStream.map(String::valueOf), stringStream).collect(Collectors.joining(","));
System.out.println(str);

或

Stream.of(...)

Stream<Integer> integerStream = IntStream.range(72, 129).boxed(); // to convert to Stream<Integer>
Stream<String> stringStream =Stream.of(" String Stream");
String str = Stream.of(integerStream.map(String::valueOf), stringStream).flatMap(t -> t).collect(Collectors.joining(","));
        System.out.println(str);

Answer 2

I'm trying to print a concat Stream that includes String and Integer elements

错误，IntStream 是原始 int 值的特定流，它与 Stream 不同，因此必须调用 IntStream::boxed 或 IntStream::mapToObj生成 Stream<?> 可用于 Stream::concat:

Stream<?> many = Stream
    .concat(part1, Stream
        .concat(part2, Stream
            .concat(part3, Stream
                .concat(part4, Stream
                    .concat(part5.boxed(), part6)
                )
            )
        )
    );

To get the result of the string concatenation as String, a terminal operation `Stream.collect(Collectors.joining())` should be applied after mapping all the objects in the streams into String using `String::valueOf` (or `Objects::toString`):
```java
String result = many.map(String::valueOf).collect(Collectors.joining());
System.out.println(result);
// -> Testing the streams concat on Java, dividing this phrase in 6 parts.

但是，这种冗长的 Stream 连接是多余的，可以使用 Stream.of + Stream::flatMap 连接 Stream。在下面的示例中，IntStream 立即映射到 String，因此不需要额外的 Stream::map：

Stream<String> many = Stream
    .of(part1, part2, part3, part4, part5.mapToObj(String::valueOf), part6)
    .flatMap(s -> s);

String res = many.collect(Collectors.joining());
System.out.println(res);
// -> Testing the streams concat on Java, dividing this phrase in 6 parts.

连接不同的流并在 Java 上打印

Concat different Streams and print on Java

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