RocMarshal commented on a change in pull request #16753:
URL: https://github.com/apache/flink/pull/16753#discussion_r685866776
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -25,37 +24,34 @@ specific language governing permissions and limitations
under the License.
-->
-# Java Lambda Expressions
+# Java Lambda 表达式
-Java 8 introduced several new language features designed for faster and
clearer coding. With the most important feature,
-the so-called "Lambda Expressions", it opened the door to functional
programming. Lambda expressions allow for implementing and
-passing functions in a straightforward way without having to declare
additional (anonymous) classes.
+Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。 作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
{{< hint info >}}
-Flink supports the usage of lambda expressions for all operators of the Java
API, however, whenever a lambda expression uses Java generics you need to
declare type information *explicitly*.
+Flink 支持对 Java API 的所有算子使用 Lambda 表达式，但是，当 Lambda 表达式使用 Java 泛型时，你需要 *显式*
声明类型信息。
Review comment:
```suggestion
Flink 支持对 Java API 的所有算子使用 Lambda 表达式，但是，当 Lambda 表达式使用 Java 泛型时，你需要 *显式*
地声明类型信息。
```
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -25,37 +24,34 @@ specific language governing permissions and limitations
under the License.
-->
-# Java Lambda Expressions
+# Java Lambda 表达式
-Java 8 introduced several new language features designed for faster and
clearer coding. With the most important feature,
-the so-called "Lambda Expressions", it opened the door to functional
programming. Lambda expressions allow for implementing and
-passing functions in a straightforward way without having to declare
additional (anonymous) classes.
+Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。 作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
{{< hint info >}}
-Flink supports the usage of lambda expressions for all operators of the Java
API, however, whenever a lambda expression uses Java generics you need to
declare type information *explicitly*.
+Flink 支持对 Java API 的所有算子使用 Lambda 表达式，但是，当 Lambda 表达式使用 Java 泛型时，你需要 *显式*
声明类型信息。
{{< /hint >}}
-This document shows how to use lambda expressions and describes current
-limitations. For a general introduction to the Flink API, please refer to the
-[DataSteam API overview]({{< ref "docs/dev/datastream/overview" >}})
+本文档介绍了如何使用 Lambda 表达式并描述了其在当前应用中的限制。有关 Flink API 的通用介绍， 请参阅[DataStream API
编程指南]({{< ref "docs/dev/datastream/overview" >}})。
-### Examples and Limitations
+## 示例和限制
-The following example illustrates how to implement a simple, inline `map()`
function that squares its input using a lambda expression.
-The types of input `i` and output parameters of the `map()` function need not
to be declared as they are inferred by the Java compiler.
+下例演示了如何实现一个简单的行内 `map()` 函数，它使用 Lambda 表达式计算输入的平方。
+
+不需要声明 `map()` 函数的输入 `i` 和输出参数的数据类型，因为 Java 编译器会对它们做出推断。
```java
env.fromElements(1, 2, 3)
-// returns the squared i
+// 返回 i 的平方
.map(i -> i*i)
.print();
```
-Flink can automatically extract the result type information from the
implementation of the method signature `OUT map(IN value)` because `OUT` is not
generic but `Integer`.
+由于 `OUT` 是 `Integer` 而不是泛型，所以 Flink 可以从方法签名 `OUT map(IN value)`
的实现中自动提取出结果的类型信息。
-Unfortunately, functions such as `flatMap()` with a signature `void flatMap(IN
value, Collector<OUT> out)` are compiled into `void flatMap(IN value, Collector
out)` by the Java compiler. This makes it impossible for Flink to infer the
type information for the output type automatically.
+不幸的是，`flatMap()` 这样的函数，它的签名 `void flatMap(IN value, Collector<OUT> out)` 被
Java 编译器编译为 `void flatMap(IN value, Collector out)`。这样 Flink 就无法自动推断输出的类型信息了。
Review comment:
```suggestion
不幸的是，像 `flatMap()` 这样的函数，它的签名 `void flatMap(IN value, Collector<OUT> out)` 被
Java 编译器编译为 `void flatMap(IN value, Collector out)`。这样 Flink 就无法自动推断输出的类型信息了。
```
Only minor comment.
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -25,37 +24,34 @@ specific language governing permissions and limitations
under the License.
-->
-# Java Lambda Expressions
+# Java Lambda 表达式
-Java 8 introduced several new language features designed for faster and
clearer coding. With the most important feature,
-the so-called "Lambda Expressions", it opened the door to functional
programming. Lambda expressions allow for implementing and
-passing functions in a straightforward way without having to declare
additional (anonymous) classes.
+Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。 作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
Review comment:
```suggestion
Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
```
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -25,37 +24,34 @@ specific language governing permissions and limitations
under the License.
-->
-# Java Lambda Expressions
+# Java Lambda 表达式
-Java 8 introduced several new language features designed for faster and
clearer coding. With the most important feature,
-the so-called "Lambda Expressions", it opened the door to functional
programming. Lambda expressions allow for implementing and
-passing functions in a straightforward way without having to declare
additional (anonymous) classes.
+Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。 作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
{{< hint info >}}
-Flink supports the usage of lambda expressions for all operators of the Java
API, however, whenever a lambda expression uses Java generics you need to
declare type information *explicitly*.
+Flink 支持对 Java API 的所有算子使用 Lambda 表达式，但是，当 Lambda 表达式使用 Java 泛型时，你需要 *显式*
声明类型信息。
{{< /hint >}}
-This document shows how to use lambda expressions and describes current
-limitations. For a general introduction to the Flink API, please refer to the
-[DataSteam API overview]({{< ref "docs/dev/datastream/overview" >}})
+本文档介绍了如何使用 Lambda 表达式并描述了其在当前应用中的限制。有关 Flink API 的通用介绍， 请参阅[DataStream API
编程指南]({{< ref "docs/dev/datastream/overview" >}})。
Review comment:
```suggestion
本文档介绍如何使用 Lambda 表达式并描述了其（Lambda 表达式）当前的限制。有关 Flink API 的通用介绍，请参阅
[DataStream API 编程指南]({{< ref "docs/dev/datastream/overview" >}})。
```
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -73,44 +69,44 @@ import org.apache.flink.util.Collector;
DataSet<Integer> input = env.fromElements(1, 2, 3);
-// collector type must be declared
+// 必须声明 collector 类型
input.flatMap((Integer number, Collector<String> out) -> {
StringBuilder builder = new StringBuilder();
for(int i = 0; i < number; i++) {
builder.append("a");
out.collect(builder.toString());
}
})
-// provide type information explicitly
+// 显式提供类型信息
.returns(Types.STRING)
-// prints "a", "a", "aa", "a", "aa", "aaa"
+// 打印 "a", "a", "aa", "a", "aa", "aaa"
.print();
```
-Similar problems occur when using a `map()` function with a generic return
type. A method signature `Tuple2<Integer, Integer> map(Integer value)` is
erasured to `Tuple2 map(Integer value)` in the example below.
+当使用 `map()` 函数返回泛型类型的时候也会发生类似的问题。下例中的方法签名 `Tuple2<Integer, Integer>
map(Integer value)` 被擦除为 `Tuple2 map(Integer value)`。
Review comment:
```suggestion
当使用 `map()` 函数返回泛型类型的时候也会发生类似的问题。下面示例中的方法签名 `Tuple2<Integer, Integer>
map(Integer value)` 被擦除为 `Tuple2 map(Integer value)`。
```
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -132,7 +128,7 @@ env.fromElements(1, 2, 3)
})
.print();
-// or in this example use a tuple subclass instead
+// 或者在这个例子中用 Tuple 的子类来替代
Review comment:
`// 或者在这个例子中用 Tuple 的子类来替代`->`// 也可以像这个示例中使用 Tuple 的子类来替代` ？
Maybe you could do it better.
##########
File path: docs/content.zh/docs/dev/datastream/java_lambdas.md
##########
@@ -25,37 +24,34 @@ specific language governing permissions and limitations
under the License.
-->
-# Java Lambda Expressions
+# Java Lambda 表达式
-Java 8 introduced several new language features designed for faster and
clearer coding. With the most important feature,
-the so-called "Lambda Expressions", it opened the door to functional
programming. Lambda expressions allow for implementing and
-passing functions in a straightforward way without having to declare
additional (anonymous) classes.
+Java 8 引入了几种新的语言特性，旨在实现更快、更清晰的编码。 作为最重要的特性，即所谓的“Lambda
表达式”，它开启了函数式编程的大门。Lambda 表达式允许以简捷的方式实现和传递函数，而无需声明额外的（匿名）类。
{{< hint info >}}
-Flink supports the usage of lambda expressions for all operators of the Java
API, however, whenever a lambda expression uses Java generics you need to
declare type information *explicitly*.
+Flink 支持对 Java API 的所有算子使用 Lambda 表达式，但是，当 Lambda 表达式使用 Java 泛型时，你需要 *显式*
声明类型信息。
{{< /hint >}}
-This document shows how to use lambda expressions and describes current
-limitations. For a general introduction to the Flink API, please refer to the
-[DataSteam API overview]({{< ref "docs/dev/datastream/overview" >}})
+本文档介绍了如何使用 Lambda 表达式并描述了其在当前应用中的限制。有关 Flink API 的通用介绍， 请参阅[DataStream API
编程指南]({{< ref "docs/dev/datastream/overview" >}})。
-### Examples and Limitations
+## 示例和限制
-The following example illustrates how to implement a simple, inline `map()`
function that squares its input using a lambda expression.
-The types of input `i` and output parameters of the `map()` function need not
to be declared as they are inferred by the Java compiler.
+下例演示了如何实现一个简单的行内 `map()` 函数，它使用 Lambda 表达式计算输入的平方。
Review comment:
```suggestion
下面的这个示例演示了如何实现一个简单的内联 `map()` 函数，它使用 Lambda 表达式计算输入值的平方。
```
Maybe you could translate it in a better way.
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