Java.Lang.Boolean源码

最新推荐文章于 2024-11-12 17:56:36 发布

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#java #Boolean #源码

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本文深入解析Java中的Boolean类，涵盖其成员变量、构造方法、成员方法如toString、hashCode、compareTo等，以及逻辑运算方法。同时介绍了如何使用valueOf方法提高空间和时间性能。

package java.lang

文章目录

package java.lang

@since JDK1.0

public final class Boolean implements java.io.Serializable, Comparable< Boolean>

成员变量

public static final Boolean TRUE = new Boolean(true)

public static final Boolean FALSE = new Boolean(false)

private final boolean value

构造方法

public Boolean(boolean value)

    public Boolean(boolean value) {
        this.value = value;
    }

public Boolean(String s)

字符串s忽略大小写后与“true”相等，则返回(Boolean)true

    public Boolean(String s) {
        this(parseBoolean(s));
    }

    public static boolean parseBoolean(String s) {
        return ((s != null) && s.equalsIgnoreCase("true"));
    }

    public boolean booleanValue() {
        return value;
    }

成员方法

官方推荐方式valueOf() for “significantly better space and time performance”

     * If a new {@code Boolean} instance is not required, this method
     * should generally be used in preference to the constructor
     * {@link #Boolean(boolean)}, as this method is likely to yield
     * significantly better space and time performance.

    public static Boolean valueOf(boolean b) {
        return (b ? TRUE : FALSE);
    }

    public static Boolean valueOf(String s) {
        return parseBoolean(s) ? TRUE : FALSE;
    }

    public static String toString(boolean b) {
        return b ? "true" : "false";
    }

toString

    public String toString() {
        return value ? "true" : "false";
    }

    @Override
    public int hashCode() {
        return Boolean.hashCode(value);
    }

hashCode

    public static int hashCode(boolean value) {
        return value ? 1231 : 1237;
    }

    public boolean equals(Object obj) {
        if (obj instanceof Boolean) {
            return value == ((Boolean)obj).booleanValue();
        }
        return false;
    }

getBoolean

获取系统属性

    public static boolean getBoolean(String name) {
        boolean result = false;
        try {
            result = parseBoolean(System.getProperty(name));
        } catch (IllegalArgumentException | NullPointerException e) {
        }
        return result;
    }

compareTo

相同为0，this.value为true返回1，b.value为true返回-1

    public int compareTo(Boolean b) {
        return compare(this.value, b.value);
    }

    public static int compare(boolean x, boolean y) {
        return (x == y) ? 0 : (x ? 1 : -1);
    }

逻辑运算

    public static boolean logicalAnd(boolean a, boolean b) {
        return a && b;
    }

    public static boolean logicalOr(boolean a, boolean b) {
        return a || b;
    }

    public static boolean logicalXor(boolean a, boolean b) {
        return a ^ b;
    }