Android example source code file (MathUtils.java)

This example Android source code file (MathUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

deg_to_rad, mathutils, rad_to_deg, random, util

The MathUtils.java Android example source code

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.util;

import java.util.Random;

/**
 * A class that contains utility methods related to numbers.
 * 
 * @hide Pending API council approval
 */
public final class MathUtils {
    private static final Random sRandom = new Random();
    private static final float DEG_TO_RAD = 3.1415926f / 180.0f;
    private static final float RAD_TO_DEG = 180.0f / 3.1415926f;

    private MathUtils() {
    }

    public static float abs(float v) {
        return v > 0 ? v : -v; 
    }

    public static int constrain(int amount, int low, int high) {
        return amount < low ? low : (amount > high ? high : amount);
    }

    public static float constrain(float amount, float low, float high) {
        return amount < low ? low : (amount > high ? high : amount);
    }

    public static float log(float a) {
        return (float) Math.log(a);
    }

    public static float exp(float a) {
        return (float) Math.exp(a);
    }

    public static float pow(float a, float b) {
        return (float) Math.pow(a, b);
    }

    public static float max(float a, float b) {
        return a > b ? a : b;
    }

    public static float max(int a, int b) {
        return a > b ? a : b;
    }

    public static float max(float a, float b, float c) {
        return a > b ? (a > c ? a : c) : (b > c ? b : c);
    }

    public static float max(int a, int b, int c) {
        return a > b ? (a > c ? a : c) : (b > c ? b : c);
    }

    public static float min(float a, float b) {
        return a < b ? a : b;
    }

    public static float min(int a, int b) {
        return a < b ? a : b;
    }

    public static float min(float a, float b, float c) {
        return a < b ? (a < c ? a : c) : (b < c ? b : c);
    }

    public static float min(int a, int b, int c) {
        return a < b ? (a < c ? a : c) : (b < c ? b : c);
    }

    public static float dist(float x1, float y1, float x2, float y2) {
        final float x = (x2 - x1);
        final float y = (y2 - y1);
        return (float) Math.sqrt(x * x + y * y);
    }

    public static float dist(float x1, float y1, float z1, float x2, float y2, float z2) {
        final float x = (x2 - x1);
        final float y = (y2 - y1);
        final float z = (z2 - z1);
        return (float) Math.sqrt(x * x + y * y + z * z);
    }

    public static float mag(float a, float b) {
        return (float) Math.sqrt(a * a + b * b);
    }

    public static float mag(float a, float b, float c) {
        return (float) Math.sqrt(a * a + b * b + c * c);
    }

    public static float sq(float v) {
        return v * v;
    }

    public static float radians(float degrees) {
        return degrees * DEG_TO_RAD;
    }

    public static float degrees(float radians) {
        return radians * RAD_TO_DEG;
    }

    public static float acos(float value) {
        return (float) Math.acos(value);
    }

    public static float asin(float value) {
        return (float) Math.asin(value);
    }

    public static float atan(float value) {
        return (float) Math.atan(value);
    }

    public static float atan2(float a, float b) {
        return (float) Math.atan2(a, b);
    }

    public static float tan(float angle) {
        return (float) Math.tan(angle);
    }    

    public static float lerp(float start, float stop, float amount) {
        return start + (stop - start) * amount;
    }
    
    public static float norm(float start, float stop, float value) {
        return (value - start) / (stop - start);
    }
    
    public static float map(float minStart, float minStop, float maxStart, float maxStop, float value) {
        return maxStart + (maxStart - maxStop) * ((value - minStart) / (minStop - minStart));
    }

    public static int random(int howbig) {
        return (int) (sRandom.nextFloat() * howbig);
    }

    public static int random(int howsmall, int howbig) {
        if (howsmall >= howbig) return howsmall;
        return (int) (sRandom.nextFloat() * (howbig - howsmall) + howsmall);
    }
    
    public static float random(float howbig) {
        return sRandom.nextFloat() * howbig;
    }

    public static float random(float howsmall, float howbig) {
        if (howsmall >= howbig) return howsmall;
        return sRandom.nextFloat() * (howbig - howsmall) + howsmall;
    }

    public static void randomSeed(long seed) {
        sRandom.setSeed(seed);
    }
}