Importing Math.PI as reference or value

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情歌与酒
情歌与酒 2021-01-15 14:44

I\'m preparing for a basic certification in Java.

I\'m a little confused by the answer to a question that I have got right(!):-

Given:

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2条回答
  •  再見小時候
    2021-01-15 14:47

    This

    import java.lang.Math.*;
    

    imports all (accessible) types declared within Math.

    This

    import java.lang.Math;
    

    is redundant because Math is part of java.lang which is imported by default.

    Both will require that you use

    Math.PI
    

    to access the field.

    This

    import static java.lang.Math.PI;
    

    imports the static member Math.PI so that you can use its simple name in your source code.

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