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BAEL-1889 - Let's move the Java Number articles into a new module (#4619)

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* BAEL-1849 - Convert from String to Date in Java

* BAEL-1863 - Calling Callbacks with Mockito

* BAEL-1889 - Let's move the Java Number articles into a new module

* BAEL-1889 - Let's move the Java Number articles into a new module
This commit is contained in:
Jonathan Cook
2018-07-14 15:00:37 +02:00
committed by Grzegorz Piwowarek
parent de2afd7da8
commit b44883b364
41 changed files with 380 additions and 188 deletions
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core-java/src/main/java/com/baeldung/maths/BigDecimalImpl.java
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package com.baeldung.maths;
import java.math.BigDecimal;
import java.math.RoundingMode;
public class BigDecimalImpl {
public static void main(String[] args) {
BigDecimal serviceTax = new BigDecimal("56.0084578639");
serviceTax = serviceTax.setScale(2, RoundingMode.CEILING);
BigDecimal entertainmentTax = new BigDecimal("23.00689");
entertainmentTax = entertainmentTax.setScale(2, RoundingMode.FLOOR);
BigDecimal totalTax = serviceTax.add(entertainmentTax);
}
}
core-java/src/main/java/com/baeldung/maths/BigIntegerImpl.java
-16
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package com.baeldung.maths;
import java.math.BigInteger;
public class BigIntegerImpl {
public static void main(String[] args) {
BigInteger numStarsMilkyWay = new BigInteger("8731409320171337804361260816606476");
BigInteger numStarsAndromeda = new BigInteger("5379309320171337804361260816606476");
BigInteger totalStars = numStarsMilkyWay.add(numStarsAndromeda);
}
}
core-java/src/main/java/com/baeldung/maths/FloatingPointArithmetic.java
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package com.baeldung.maths;
import java.math.BigDecimal;
public class FloatingPointArithmetic {
public static void main(String[] args) {
double a = 13.22;
double b = 4.88;
double c = 21.45;
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("c = " + c);
double sum_ab = a + b;
System.out.println("a + b = " + sum_ab);
double abc = a + b + c;
System.out.println("a + b + c = " + abc);
double ab_c = sum_ab + c;
System.out.println("ab + c = " + ab_c);
double sum_ac = a + c;
System.out.println("a + c = " + sum_ac);
double acb = a + c + b;
System.out.println("a + c + b = " + acb);
double ac_b = sum_ac + b;
System.out.println("ac + b = " + ac_b);
double ab = 18.1;
double ac = 34.67;
double sum_ab_c = ab + c;
double sum_ac_b = ac + b;
System.out.println("ab + c = " + sum_ab_c);
System.out.println("ac + b = " + sum_ac_b);
BigDecimal d = new BigDecimal(String.valueOf(a));
BigDecimal e = new BigDecimal(String.valueOf(b));
BigDecimal f = new BigDecimal(String.valueOf(c));
BigDecimal def = d.add(e).add(f);
BigDecimal dfe = d.add(f).add(e);
System.out.println("d + e + f = " + def);
System.out.println("d + f + e = " + dfe);
}
}
core-java/src/main/java/com/baeldung/maths/Round.java
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package com.baeldung.maths;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import org.apache.commons.math3.util.Precision;
import org.decimal4j.util.DoubleRounder;
public class Round {
private static final double PI = 3.1415d;
public static void main (String args[]) {
System.out.println("PI: " + PI);
System.out.printf("Value with 3 digits after decimal point %.3f %n", PI);
// OUTPUTS: Value with 3 digits after decimal point 3.142
DecimalFormat df = new DecimalFormat("###.###");
System.out.println(df.format(PI));
System.out.println(round(PI, 3));
System.out.println(roundNotPrecise(PI, 3));
System.out.println(roundAvoid(PI, 3));
System.out.println(Precision.round(PI, 3));
System.out.println(DoubleRounder.round(PI, 3));
}
public static double round(double value, int places) {
if (places < 0) throw new IllegalArgumentException();
BigDecimal bd = new BigDecimal(Double.toString(value));
bd = bd.setScale(places, RoundingMode.HALF_UP);
return bd.doubleValue();
}
public static double roundNotPrecise(double value, int places) {
if (places < 0) throw new IllegalArgumentException();
BigDecimal bd = new BigDecimal(value);
bd = bd.setScale(places, RoundingMode.HALF_UP);
return bd.doubleValue();
}
public static double roundAvoid(double value, int places) {
double scale = Math.pow(10, places);
double rounded = Math.round(value * scale) / scale;
return rounded;
}
}
core-java/src/main/java/com/baeldung/nan/NaNExample.java
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package com.baeldung.nan;
/**
* Sample usage of NaN.
*
*/
public class NaNExample {
public static void main(String[] args) {
NaNExample naNExample = new NaNExample();
naNExample.demo();
}
void demo() {
undefined_operations_produce_NaN();
operations_with_no_real_results_produce_NaN();
operations_with_NaN_produce_NaN();
comparison_with_NaN();
check_if_a_value_is_NaN();
assign_NaN_to_missing_values();
}
void undefined_operations_produce_NaN() {
System.out.println("Undefined Operations Produce NaN");
final double ZERO = 0;
System.out.println("ZERO / ZERO = " + (ZERO / ZERO));
System.out.println("INFINITY - INFINITY = " + (Double.POSITIVE_INFINITY - Double.POSITIVE_INFINITY));
System.out.println("INFINITY * ZERO = " + (Double.POSITIVE_INFINITY * ZERO));
System.out.println();
}
void operations_with_no_real_results_produce_NaN() {
System.out.println("Operations with no real results produce NaN");
System.out.println("SQUARE ROOT OF -1 = " + Math.sqrt(-1));
System.out.println("LOG OF -1 = " + Math.log(-1));
System.out.println();
}
void operations_with_NaN_produce_NaN() {
System.out.println("Operations with NaN produce NaN");
System.out.println("2 + NaN = " + (2 + Double.NaN));
System.out.println("2 - NaN = " + (2 - Double.NaN));
System.out.println("2 * NaN = " + (2 * Double.NaN));
System.out.println("2 / NaN = " + (2 / Double.NaN));
System.out.println();
}
void assign_NaN_to_missing_values() {
System.out.println("Assign NaN to Missing values");
double salaryRequired = Double.NaN;
System.out.println(salaryRequired);
System.out.println();
}
void comparison_with_NaN() {
System.out.println("Comparison with NaN");
final double NAN = Double.NaN;
System.out.println("NaN == 1 = " + (NAN == 1));
System.out.println("NaN > 1 = " + (NAN > 1));
System.out.println("NaN < 1 = " + (NAN < 1));
System.out.println("NaN != 1 = " + (NAN != 1));
System.out.println("NaN == NaN = " + (NAN == NAN));
System.out.println("NaN > NaN = " + (NAN > NAN));
System.out.println("NaN < NaN = " + (NAN < NAN));
System.out.println("NaN != NaN = " + (NAN != NAN));
System.out.println();
}
void check_if_a_value_is_NaN() {
System.out.println("Check if a value is NaN");
double x = 1;
System.out.println(x + " is NaN = " + (x != x));
System.out.println(x + " is NaN = " + (Double.isNaN(x)));
x = Double.NaN;
System.out.println(x + " is NaN = " + (x != x));
System.out.println(x + " is NaN = " + (Double.isNaN(x)));
System.out.println();
}
}
core-java/src/main/java/com/baeldung/numberofdigits/Benchmarking.java
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package com.baeldung.numberofdigits;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.runner.RunnerException;
public class Benchmarking {
public static void main(String[] args) throws RunnerException, IOException {
org.openjdk.jmh.Main.main(args);
}
@State(Scope.Thread)
public static class ExecutionPlan {
public int number = Integer.MAX_VALUE;
public int length = 0;
public NumberOfDigits numberOfDigits= new NumberOfDigits();
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void stringBasedSolution(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.stringBasedSolution(plan.number);
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void logarithmicApproach(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.logarithmicApproach(plan.number);
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void repeatedMultiplication(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.repeatedMultiplication(plan.number);
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void shiftOperators(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.shiftOperators(plan.number);
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void dividingWithPowersOf2(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.dividingWithPowersOf2(plan.number);
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public void divideAndConquer(ExecutionPlan plan) {
plan.length = plan.numberOfDigits.divideAndConquer(plan.number);
}
}
core-java/src/main/java/com/baeldung/numberofdigits/NumberOfDigits.java
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package com.baeldung.numberofdigits;
public class NumberOfDigits {
public int stringBasedSolution(int number) {
int length = String.valueOf(number).length();
return length;
}
public int logarithmicApproach(int number) {
int length = (int) Math.log10(number) + 1;
return length;
}
public int repeatedMultiplication(int number) {
int length = 0;
long temp = 1;
while(temp <= number) {
length++;
temp *= 10;
}
return length;
}
public int shiftOperators(int number) {
int length = 0;
long temp = 1;
while(temp <= number) {
length++;
temp = (temp << 3) + (temp << 1);
}
return length;
}
public int dividingWithPowersOf2(int number) {
int length = 1;
if (number >= 100000000) {
length += 8;
number /= 100000000;
}
if (number >= 10000) {
length += 4;
number /= 10000;
}
if (number >= 100) {
length += 2;
number /= 100;
}
if (number >= 10) {
length += 1;
}
return length;
}
public int divideAndConquer(int number) {
if (number < 100000){
// 5 digits or less
if (number < 100){
// 1 or 2
if (number < 10)
return 1;
else
return 2;
}else{
// 3 to 5 digits
if (number < 1000)
return 3;
else{
// 4 or 5 digits
if (number < 10000)
return 4;
else
return 5;
}
}
} else {
// 6 digits or more
if (number < 10000000) {
// 6 or 7 digits
if (number < 1000000)
return 6;
else
return 7;
} else {
// 8 to 10 digits
if (number < 100000000)
return 8;
else {
// 9 or 10 digits
if (number < 1000000000)
return 9;
else
return 10;
}
}
}
}
}
core-java/src/main/java/com/baeldung/numberofdigits/NumberOfDigitsDriver.java
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package com.baeldung.numberofdigits;
import org.apache.log4j.Logger;
public class NumberOfDigitsDriver {
private static NumberOfDigits numberOfDigits;
private static Logger LOG = Logger.getLogger(NumberOfDigitsDriver.class);
static {
numberOfDigits = new NumberOfDigits();
}
public static void main(String[] args) {
LOG.info("Testing all methods...");
long length = numberOfDigits.stringBasedSolution(602);
LOG.info("String Based Solution : " + length);
length = numberOfDigits.logarithmicApproach(602);
LOG.info("Logarithmic Approach : " + length);
length = numberOfDigits.repeatedMultiplication(602);
LOG.info("Repeated Multiplication : " + length);
length = numberOfDigits.shiftOperators(602);
LOG.info("Shift Operators : " + length);
length = numberOfDigits.dividingWithPowersOf2(602);
LOG.info("Dividing with Powers of 2 : " + length);
length = numberOfDigits.divideAndConquer(602);
LOG.info("Divide And Conquer : " + length);
}
}
core-java/src/main/java/com/baeldung/pow/PowerExample.java
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package com.baeldung.pow;
import java.text.DecimalFormat;
public class PowerExample {
public static void main(String[] args) {
int intResult = (int) Math.pow(2, 3);
System.out.println("Math.pow(2, 3) = " + intResult);
double dblResult = Math.pow(4.2, 3);
System.out.println("Math.pow(4.2, 3) = " + Math.pow(4.2, 3));
DecimalFormat df = new DecimalFormat(".00");
System.out.println("Math.pow(4.2, 3) rounded = " + df.format(dblResult));
}
}