双流。Java中的Builder add（双t）及其示例-yiteyi-C++库

双流。建筑商添加（双t） 用于在流的构建阶段将图元插入到图元中。它向正在构建的流中添加一个元素。

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语法：

default DoubleStream.Builder add(double t)

参数： 此方法接受一个强制参数 T 这是要输入到流中的元素。

例外情况： 这个方法抛出 非法州例外： 当构建器已转换为已构建状态时。这意味着流已经进入了构建阶段，现在不能更改。因此，不能向流中添加更多元素。

下面是示例来说明add（）方法：

例1：

                     // Java code to show the implementation                   
                     // of DoubleStream.Builder add(double t)                   
                             
                     import                               java.util.stream.DoubleStream;                   
                             
                     class                               GFG {                   
                             
                                         // Driver code                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Declaring an empty Stream                   
                                         DoubleStream.Builder b = DoubleStream.builder();                   
                             
                                         // Inserting elements into the stream                   
                                         // using DoubleStream.Builder add(double t)                   
                                         b.add(                               4.4                               );                   
                                         b.add(                               5.84                               );                   
                                         b.add(                               6                               );                   
                                         b.add(                               7.47                               );                   
                             
                                         // Creating the Stream                   
                                         // The stream has now entered the built phase                   
                                         // printing the elements                   
                                         System.out.println(                               "Stream successfully built"                               );                   
                                         b.build().forEach(System.out::println);                   
                                         }                   
                     }                   

输出：

Stream successfully built
4.4
5.84
6.0
7.47

例2： 来说明非法的例外情况

                     // Java code to show the implementation                   
                     // of DoubleStream.Builder add(T t)                   
                             
                     import                               java.util.stream.DoubleStream;                   
                             
                     class                               GFG {                   
                             
                                         // Driver code                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Declaring an empty Stream                   
                                         DoubleStream.Builder b = DoubleStream.builder();                   
                             
                                         // using DoubleStream.Builder add(T t)                   
                                         b.add(                               4.7                               );                   
                                         b.add(                               5.9                               );                   
                                         b.add(                               6                               );                   
                                         b.add(                               7.785                               );                   
                             
                                         // Creating the Stream                   
                                         // The stream has now entered the built phase                   
                                         // printing the elements                   
                                         System.out.println(                               "Stream successfully built"                               );                   
                                         b.build().forEach(System.out::println);                   
                             
                                         // Trying to add another element into the stream                   
                                         // Since the Stream is in built phase                   
                                         // This operation is not possible now                   
                                         // Hence add() will throw exception now                   
                             
                                         try                               {                   
                                         b.add(                               50.784                               );                   
                                         }                   
                                         catch                               (Exception e) {                   
                                         System.out.println(                               "Exception thrown "                   
                                         +                               "when now adding element into the stream: "                   
                                         + e);                   
                                         }                   
                                         }                   
                     }                   

输出：

Stream successfully built
4.7
5.9
6.0
7.785
Exception thrown when now adding element into the stream: java.lang.IllegalStateException

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