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Java - Math.round() method example
0 points
Math.round is a static method that returns a number that is rounded to the closest integer number.
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public class MathExample {2
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public static void main(String[] args) {4
System.out.println( Math.round( 5 ) ); // 55
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System.out.println( Math.round( 2.49 ) ); // 27
System.out.println( Math.round( 2.50 ) ); // 38
System.out.println( Math.round( 2.51 ) ); // 39
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System.out.println( Math.round( -2.49 ) ); // -211
System.out.println( Math.round( -2.50 ) ); // -212
System.out.println( Math.round( -2.51 ) ); // -313
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System.out.println( Math.round( 0.999 ) ); // 115
System.out.println( Math.round( 1.001 ) ); // 116
System.out.println( Math.round( -1.001 ) ); // -117
}18
}| Syntax |
xxxxxxxxxx1 package java.lang;2 3 public final class Math {4 5 public static long round(double number) { ... }6 public static int round(float number) { ... }7 8 }
|
| Parameters | number - primitive value. |
| Result | Rounded number value (primitive value). |
| Description | round is a static method that returns a number that is rounded to the closest integer number. |
This section contains a custom function that shows how to round number with precision to n places.
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public class MathExample {2
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static double roundPrecised(double number, int precision) {4
double power = Math.pow(10, precision);5
return Math.round(number * power) / power;6
}7
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public static void main(String[] args) {9
// Example:10
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System.out.println( roundPrecised( 5 , 0 ) ); // 5.012
System.out.println( roundPrecised( 5. , 0 ) ); // 5.013
System.out.println( roundPrecised( .5, 0 ) ); // 1.014
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System.out.println( roundPrecised( 1.2345, 0 ) ); // 1.016
System.out.println( roundPrecised( 1.2345, 1 ) ); // 1.217
System.out.println( roundPrecised( 1.2345, 2 ) ); // 1.2318
System.out.println( roundPrecised( 1.2345, 3 ) ); // 1.23519
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System.out.println( roundPrecised( -1.2345, 0 ) ); // -1.021
System.out.println( roundPrecised( -1.2345, 1 ) ); // -1.222
System.out.println( roundPrecised( -1.2345, 2 ) ); // -1.2323
System.out.println( roundPrecised( -1.2345, 3 ) ); // -1.23424
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System.out.println( roundPrecised( 12345, -1 ) ); // 12350.026
System.out.println( roundPrecised( 12345, -2 ) ); // 12300.027
System.out.println( roundPrecised( 12345, -3 ) ); // 12000.028
}29
}This section contains custom round function implementation.
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public class MathExample {2
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static double roundNumber(double value) {4
if (value < 0.0) {5
double rest = (value % 1.0);6
if (rest < -0.5) {7
rest += 1.0;8
}9
return value - rest;10
} else {11
value += 0.5;12
return value - (value % 1.0);13
}14
}15
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public static void main(String[] args) {17
// Example:18
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System.out.println( roundNumber( 5 ) ); // 5.020
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System.out.println( roundNumber( 2.49 ) ); // 2.022
System.out.println( roundNumber( 2.50 ) ); // 3.023
System.out.println( roundNumber( 2.51 ) ); // 3.024
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System.out.println( roundNumber( 0.999 ) ); // 1.026
System.out.println( roundNumber( 1.001 ) ); // 1.027
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System.out.println( roundNumber( -2.49 ) ); // -2.029
System.out.println( roundNumber( -2.50 ) ); // -2.030
System.out.println( roundNumber( -2.51 ) ); // -3.031
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System.out.println( roundNumber( -1.001 ) ); // -1.033
}34
}
