1.概述

转载：jdk源码分析-------------boolean

这篇文章小编只是对boolean类型的几个方法进行一次知识梳理，大家有好的意见可以在留言区留下宝贵的意见，小编会做出相应的调整。

1.1 booleanValue()

   /*** Returns the value of this {@code Boolean} object as a boolean* primitive.** @return  the primitive {@code boolean} value of this object.*/public boolean booleanValue() {return value;}

这个方法返回的是当前这个boolean类型对象的内容。

boolean b=true;
System.out.println(b.booleanValue());
----------------------------------------
true

1.2 toString()

/*** Returns a {@code String} object representing this Boolean's* value.  If this object represents the value {@code true},* a string equal to {@code "true"} is returned. Otherwise, a* string equal to {@code "false"} is returned.** @return  a string representation of this object.*/
public String toString() {return value ? "true" : "false";
}

这个方法返回类型是string，返回的是boolean对象的内容

boolean b=false;
System.out.println(b.booleanValue());
----------------------------------------
false

1.3 hashCode()

   /*** Returns a hash code for this {@code Boolean} object.** @return  the integer {@code 1231} if this object represents* {@code true}; returns the integer {@code 1237} if this* object represents {@code false}.*/@Overridepublic int hashCode() {return Boolean.hashCode(value);}/*** Returns a hash code for a {@code boolean} value; compatible with* {@code Boolean.hashCode()}.** @param value the value to hash* @return a hash code value for a {@code boolean} value.* @since 1.8*/public static int hashCode(boolean value) {return value ? 1231 : 1237;}

当调用hashCode返回的是true或者false的哈希值。在hashCode这个方法中通过三目表达式表现出来。

1.4 compareTo()

 /*** Compares this {@code Boolean} instance with another.** @param   b the {@code Boolean} instance to be compared* @return  zero if this object represents the same boolean value as the*          argument; a positive value if this object represents true*          and the argument represents false; and a negative value if*          this object represents false and the argument represents true* @throws  NullPointerException if the argument is {@code null}* @see     Comparable* @since  1.5*/public int compareTo(Boolean b) {return compare(this.value, b.value);}/*** Compares two {@code boolean} values.* The value returned is identical to what would be returned by:* <pre>*    Boolean.valueOf(x).compareTo(Boolean.valueOf(y))* </pre>** @param  x the first {@code boolean} to compare* @param  y the second {@code boolean} to compare* @return the value {@code 0} if {@code x == y};*         a value less than {@code 0} if {@code !x && y}; and*         a value greater than {@code 0} if {@code x && !y}* @since 1.7*/public static int compare(boolean x, boolean y) {return (x == y) ? 0 : (x ? 1 : -1);}

调用这个方法时会拿当前对象和要比较的对象value进行比较。compare方法最终定义只能返回1或者-1。

1.5 equals()

   /*** Returns {@code true} if and only if the argument is not* {@code null} and is a {@code Boolean} object that* represents the same {@code boolean} value as this object.** @param   obj   the object to compare with.* @return  {@code true} if the Boolean objects represent the*          same value; {@code false} otherwise.*/public boolean equals(Object obj) {if (obj instanceof Boolean) {return value == ((Boolean)obj).booleanValue();}return false;}

如果当前对象时boolean的实例，就返回这个对象的内容，否则返回false

N.扩展阅读

AtomicBoolean介绍与使用

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