【Android】解决FloatMath类中方法在API 23以

1.问题原因分析

在Android SDK更新至23以上时，我们会发现之前在某些地方因计算需要使用到的FloatMath类中的方法如FloatMath.ceil()与FloatMath.sin()等都报错并提示不可用了，FloatMath源码如下：

package android.util;

/**
 * Math routines similar to those found in {@link java.lang.Math}.
 * 数学例程类似于{@link java.lang.Math}.
 * <p>Historically these methods were faster than the equivalent double-based
 * {@link java.lang.Math} methods. On versions of Android with a JIT they
 * became slower and have since been re-implemented to wrap calls to
 * {@link java.lang.Math}. {@link java.lang.Math} should be used in
 * preference.
 *
 * <p>All methods were removed from the public API in version 23.
 * 所有方法都从版本23的公共API中删除.
 * @deprecated Use {@link java.lang.Math} instead.
 * 方法过时，应使用java.lang.Math代替.
 */
@Deprecated
public class FloatMath {

    /** Prevents instantiation. */
    private FloatMath() {}

    /**
     * Returns the float conversion of the most positive (i.e. closest to
     * positive infinity) integer value which is less than the argument.
     *
     * @param value to be converted
     * @return the floor of value
     * @removed
     */
    public static float floor(float value) {
        return (float) Math.floor(value);
    }

    /**
     * Returns the float conversion of the most negative (i.e. closest to
     * negative infinity) integer value which is greater than the argument.
     *
     * @param value to be converted
     * @return the ceiling of value
     * @removed
     */
    public static float ceil(float value) {
        return (float) Math.ceil(value);
    }

    /**
     * Returns the closest float approximation of the sine of the argument.
     *
     * @param angle to compute the cosine of, in radians
     * @return the sine of angle
     * @removed
     */
    public static float sin(float angle) {
        return (float) Math.sin(angle);
    }

    /**
     * Returns the closest float approximation of the cosine of the argument.
     *
     * @param angle to compute the cosine of, in radians
     * @return the cosine of angle
     * @removed
     */
    public static float cos(float angle) {
        return (float) Math.cos(angle);
    }

    /**
     * Returns the closest float approximation of the square root of the
     * argument.
     *
     * @param value to compute sqrt of
     * @return the square root of value
     * @removed
     */
    public static float sqrt(float value) {
        return (float) Math.sqrt(value);
    }

    /**
     * Returns the closest float approximation of the raising "e" to the power
     * of the argument.
     *
     * @param value to compute the exponential of
     * @return the exponential of value
     * @removed
     */
    public static float exp(float value) {
        return (float) Math.exp(value);
    }

    /**
     * Returns the closest float approximation of the result of raising {@code
     * x} to the power of {@code y}.
     *
     * @param x the base of the operation.
     * @param y the exponent of the operation.
     * @return {@code x} to the power of {@code y}.
     * @removed
     */
    public static float pow(float x, float y) {
        return (float) Math.pow(x, y);
    }

    /**
     * Returns {@code sqrt(}<i>{@code x}</i><sup>{@code 2}</sup>{@code +} <i>
     * {@code y}</i><sup>{@code 2}</sup>{@code )}.
     *
     * @param x a float number
     * @param y a float number
     * @return the hypotenuse
     * @removed
     */
    public static float hypot(float x, float y) {
        return (float) Math.hypot(x, y);
    }
}

通过观察类说明可知，FloatMath的所有方法都已经从版本23的公共API中删除，官方提示我们可以使用java.lang.Math类来代替使用。

2.解决方法

• 使用23以下版本的SDK进行编译，即修改gradle.build文件里的compileSdkVersion为23以下版本即可。
• 使用Math类中的方法进行代替。