99 lines
2.9 KiB
Java
99 lines
2.9 KiB
Java
package appeng.util;
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import java.math.RoundingMode;
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import java.text.DecimalFormat;
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import java.text.DecimalFormatSymbols;
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import java.text.Format;
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/**
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* Converter class to convert a large number into a SI system.
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*
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* @author thatsIch
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* @version rv2
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* @since rv2
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*/
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public enum ReadableNumberConverter
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implements ISlimReadableNumberConverter, IWideReadableNumberConverter {
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INSTANCE;
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/**
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* Defines the base for a division, non-si standard could be 1024 for kilobytes
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*/
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private static final int DIVISION_BASE = 1000;
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/**
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* String representation of the sorted postfixes
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*/
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private static final char[] ENCODED_POSTFIXES = "KMGTPE".toCharArray();
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private final Format format;
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/**
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* Initializes the specific decimal format with special format for negative and
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* positive numbers
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*/
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ReadableNumberConverter() {
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final DecimalFormatSymbols symbols = new DecimalFormatSymbols();
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symbols.setDecimalSeparator('.');
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final DecimalFormat format = new DecimalFormat(".#;0.#");
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format.setDecimalFormatSymbols(symbols);
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format.setRoundingMode(RoundingMode.DOWN);
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this.format = format;
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}
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@Override
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public String toSlimReadableForm(final long number) {
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return this.toReadableFormRestrictedByWidth(number, 3);
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}
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/**
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* restricts a string representation of a number to a specific width
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*
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* @param number to be formatted number
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* @param width width limitation of the resulting number
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* @return formatted number restricted by the width limitation
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*/
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private String toReadableFormRestrictedByWidth(final long number, final int width) {
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assert number >= 0;
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// handles low numbers more efficiently since no format is needed
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final String numberString = Long.toString(number);
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int numberSize = numberString.length();
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if (numberSize <= width) {
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return numberString;
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}
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long base = number;
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double last = base * 1000;
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int exponent = -1;
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String postFix = "";
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while (numberSize > width) {
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last = base;
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base /= DIVISION_BASE;
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exponent++;
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// adds +1 due to the postfix
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numberSize = Long.toString(base).length() + 1;
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postFix = String.valueOf(ENCODED_POSTFIXES[exponent]);
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}
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final String withPrecision = this.format.format(last / DIVISION_BASE) + postFix;
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final String withoutPrecision = Long.toString(base) + postFix;
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final String slimResult
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= (withPrecision.length() <= width) ? withPrecision : withoutPrecision;
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// post condition
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assert slimResult.length() <= width;
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return slimResult;
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}
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@Override
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public String toWideReadableForm(final long number) {
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return this.toReadableFormRestrictedByWidth(number, 4);
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}
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}
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