Java中的 DoubleStream.Builder add(double t) 和示例

DoubleStream.Builder add(double t)用于在流的构建阶段将元素插入到元素中。它将一个元素添加到正在构建的流中。

句法：

default DoubleStream.Builder add(double t)

参数：此方法接受一个强制参数t ，它是要输入到流中的元素。

异常：此方法抛出IllegalStateException：当构建器已经转换到构建状态时。这意味着流已进入构建阶段，现在不能更改。因此，不能将更多元素添加到流中。

以下是说明 add() 方法的示例：

示例 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

示例 2：说明 IllegalStateException

// 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