Java Switch 不兼容类型 Boolean Int
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Java Switch Incompatible Types Boolean Int
提问by iTEgg
I have the following class:
我有以下课程：
public class NewGameContract {
public boolean HomeNewGame = false;
public boolean AwayNewGame = false;
public boolean GameContract(){
if (HomeNewGame && AwayNewGame){
return true;
} else {
return false;
}
}
}
When I try to use it like so:
当我尝试像这样使用它时：
if (networkConnection){
connect4GameModel.newGameContract.HomeNewGame = true;
boolean status = connect4GameModel.newGameContract.GameContract();
switch (status){
case true:
break;
case false:
break;
}
return;
}
I am getting the error:
我收到错误：
incompatible types found: boolean required: int on the following
`switch (status)` code.
What am I doing wrong?
我究竟做错了什么？
回答by chris
you don't want to switchon a boolean, just use a simple if/else
您不想switch使用布尔值，只需使用简单的if/else
if (status) {
....
} else {
....
}
edit : switchis only used for ints, chars, or enums (i think that's all, maybe there are others?)
edit edit : it seems shortand byteare also valid types for switching, as well as the boxed versions of all of these (Integer, Short, etc etc)
编辑：switch仅用于intS，charS或enumS（我认为这是所有的，也许还有其他？）编辑编辑：好像short和byte也适用类型的开关，以及所有这些的盒装版本（Integer，Short，等等等等）
回答by polygenelubricants
You can't switch on a boolean(which only have 2 values anyway):
您无法打开 a boolean（无论如何只有 2 个值）：
The Java Language Specification clearly specifies what type of expression can be switch-ed on.
Java 语言规范明确指定了可以使用的表达式类型switch。
JLS 14.11 The switch statement
JLS 14.11 switch 语句
SwitchStatement: switch ( Expression ) SwitchBlockThe type of the
Expressionmust bechar,byte,short,int,Character,Byte,Short,Integer, or anenumtype, or a compile-time error occurs.
SwitchStatement: switch ( Expression ) SwitchBlock的类型
Expression必须是char,byte,short,int,Character,Byte,Short,Integer, 或enum类型，否则会发生编译时错误。
It is a lot more readable and concise to simply use an ifstatement to distinguish the two cases of boolean.
简单地使用一个if语句来区分 的两种情况会更具可读性和简洁性boolean。
回答by Shailesh Saxena
Switch statements in Java can use byte, short, char, and int (note: not long) primitive data types or their corresponding wrapper types. Starting with J2SE 5.0, it became possible to use enum types. Starting with Java SE 7, it became possible to use Strings.
Java 中的 switch 语句可以使用 byte、short、char 和 int（注意：不是 long）原始数据类型或其相应的包装类型。从 J2SE 5.0 开始，可以使用枚举类型。从 Java SE 7 开始，可以使用字符串。
回答by John Smith
Switch takes an integer value, and a boolean cannot be converted to an integer.
Switch 取整数值，布尔值不能转换为整数。
In java, a boolean is a type in its own right, and not implicitly convertible to any other type (except Boolean).
在 java 中，布尔值本身就是一种类型，不能隐式转换为任何其他类型（布尔值除外）。
回答by duffymo
Can't use boolean in switch, only int. Please read the Java docs for the switch statement.
不能在 switch 中使用 boolean，只能使用 int。请阅读有关 switch 语句的 Java 文档。
回答by Dónal Boyle
In Java, switch only works for byte, short, char, int and enum. For booleans you should use if/else as there are a very limited number of states.
在 Java 中，switch 仅适用于 byte、short、char、int 和 enum。对于布尔值，您应该使用 if/else，因为状态数量非常有限。
