Boolean和其基本类型boolean的区别
hello，大家好，这里是可傥。今天我们来说一下基本数据类型boolean和其包装类Boolean。
今天我们结合以下例子来说明这两者的区别。
public class BooleanTest {
private Boolean isTrue;
/**
* Getter method for property<tt>isTrue</tt>.
*
* @return property value of isTrue
*/
public Boolean getTrue() {
return isTrue;
}
/**
* Setter method for property <tt>isTrue</tt>.
*
* @param isTrue value to be assigned to property isTrue
*/
public void
setTrue(Boolean isTrue) {
this.isTrue = isTrue;
}
public static void main(String[] args) {
//boolean a = null;
Boolean a = null;
Boolean b = new Boolean(null);
Boolean c = new Boolean("true");
if (null ==a){
a =true;
}
System.out.println(a);
System.out.println(b);
BooleanTest booleanTest = new BooleanTest();
booleanTest.setTrue(null);
System.out.println(booleanTest.isTrue);
System.out.println(booleanTest.getTrue());
}
}
一、是否可以为null
Boolean因为是一个类，所以他的引用对象可以为null； Boolean a= null或者Boolean b = new Boolean(null)都是允许的，而基本数据类型boolean只能为true or false。
二、Boolean 可以 new 中引入字符串
要知道Boolean为什么可以new中加入字符串，我们就打开Boolean的源码，源码是这样的：
/**
* Allocates a {@code Boolean} object representing the value
* {@code true} if the string argument is not {@code null}
* and is equal, ignoring case, to the string {@code "true"}.
* Otherwise, allocate a {@code Boolean} object representing the
* value {@code false}. Examples:<p>
* {@code new Boolean("True")} produces a {@code Boolean} object
* that represents {@code true}.<br>
* {@code new Boolean("yes")} produces a {@code Boolean} object
* that represents {@code false}.
*
* @param s the string to be converted to a {@code Boolean}.
*/
public Boolean(String s) {
this(parseBoolean(s));
}
/**
* Parses the string argument as a boolean. The {@code boolean}
* returned represents the value {@code true} if the string argument
* is not {@code null} and is equal, ignoring case, to the string
* {@code "true"}. <p>
* Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
* Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
*
* @param s the {@code String} containing the boolean
* representation to be parsed
* @return the boolean represented by the string argument
* @since 1.5
*/
public static boolean parseBoolean(String s) {
return ((s != null) && s.equalsIgnoreCase("true"));
}
这边就可以很明显的看到，字符串唯有"true"且不为null的时候才是true(true不区分大小写)，其他全部为false。
