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Java compact1, compact2, compact3 java.util Class IntSummaryStatistics（JDK8）

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Java™ Platform
Standard Ed. 8
compact1, compact2, compact3
java.util

Class IntSummaryStatistics

  • All Implemented Interfaces:
    IntConsumer 

    public class IntSummaryStatistics
extends Object
implements IntConsumer
    A state object for collecting statistics such as count, min, max, sum, and average.

    This class is designed to work with (though does not require) streams. For example, you can compute summary statistics on a stream of ints with:

     
 IntSummaryStatistics stats = intStream.collect(IntSummaryStatistics::new,
                                                IntSummaryStatistics::accept,
                                                IntSummaryStatistics::combine);

    IntSummaryStatistics can be used as a reduction target for a stream. For example:

     
 IntSummaryStatistics stats = people.stream()
                                    .collect(Collectors.summarizingInt(Person::getDependents));
    This computes, in a single pass, the count of people, as well as the minimum, maximum, sum, and average of their number of dependents.
    Implementation Note:
    This implementation is not thread safe. However, it is safe to use Collectors.toIntStatistics() on a parallel stream, because the parallel implementation of Stream.collect() provides the necessary partitioning, isolation, and merging of results for safe and efficient parallel execution.

    This implementation does not check for overflow of the sum.

    Since:
    1.8

    • Constructor Summary

      Constructors 
      Constructor and Description
      IntSummaryStatistics()
      Construct an empty instance with zero count, zero sum, Integer.MAX_VALUE min, Integer.MIN_VALUE max and zero average.

    • Constructor Detail

      • IntSummaryStatistics

        public IntSummaryStatistics()
        Construct an empty instance with zero count, zero sum, Integer.MAX_VALUE min, Integer.MIN_VALUE max and zero average.

    • Method Detail

      • accept

        public void accept(int value)
        Records a new value into the summary information
        Specified by:
        accept in interface IntConsumer
        Parameters:
        value - the input value

      • combine

        public void combine(IntSummaryStatistics other)
        Combines the state of another IntSummaryStatistics into this one.
        Parameters:
        other - another IntSummaryStatistics
        Throws:
        NullPointerException - if other is null

      • getCount

        public final long getCount()
        Returns the count of values recorded.
        Returns:
        the count of values

      • getSum

        public final long getSum()
        Returns the sum of values recorded, or zero if no values have been recorded.
        Returns:
        the sum of values, or zero if none

      • getMin

        public final int getMin()
        Returns the minimum value recorded, or Integer.MAX_VALUE if no values have been recorded.
        Returns:
        the minimum value, or Integer.MAX_VALUE if none

      • getMax

        public final int getMax()
        Returns the maximum value recorded, or Integer.MIN_VALUE if no values have been recorded.
        Returns:
        the maximum value, or Integer.MIN_VALUE if none

      • getAverage

        public final double getAverage()
        Returns the arithmetic mean of values recorded, or zero if no values have been recorded.
        Returns:
        the arithmetic mean of values, or zero if none

      • toString

        public String toString()
        Description copied from class: Object
        Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

        The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

         getClass().getName() + '@' + Integer.toHexString(hashCode())
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.
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Java™ Platform
Standard Ed. 8

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