更改布尔值?

2022-01-19 00:00:00 boolean java primitive-types

我对 Java 中的布尔值有疑问.假设我有一个这样的程序:

I have a question about boolean values in Java. Let's say I have a program like this:

boolean test = false;
...
foo(test)
foo2(test)

foo(Boolean test){
  test = true;
}
foo2(Boolean test){
  if(test)
   //Doesn't go in here
}

我注意到在 foo2 中，布尔测试没有改变，因此不会进入 if 语句.那我怎么改呢?我查看了布尔值，但找不到将测试从真设置"为假的函数.如果有人可以帮助我，那就太好了.

I noticed that in foo2, the boolean test does not change and thereby doesn't go into the if statement. How would I go about changing it then? I looked into Boolean values but I couldn't find a function that would "set" test from true to false. If anyone could help me out that would be great.

推荐答案

您将原始布尔值传递给您的函数，没有引用".因此，您只是在 foo 方法中隐藏值.相反，您可能想要使用以下之一 -

You're passing the value of a primitive boolean to your function, there is no "reference". So you're only shadowing the value within your foo method. Instead, you might want to use one of the following -

持有人

public static class BooleanHolder {
  public Boolean value;
}

private static void foo(BooleanHolder test) {
  test.value = true;
}

private static void foo2(BooleanHolder test) {
  if (test.value)
    System.out.println("In test");
  else
    System.out.println("in else");
}

public static void main(String[] args) {
  BooleanHolder test = new BooleanHolder();
  test.value = false;
  foo(test);
  foo2(test);
}

输出测试中".

或者，通过使用

成员变量

private boolean value = false;

public void foo() {
  this.value = true;
}

public void foo2() {
  if (this.value)
    System.out.println("In test");
  else
    System.out.println("in else");
}

public static void main(String[] args) {
  BooleanQuestion b = new BooleanQuestion();
  b.foo();
  b.foo2();
}

其中，也输出In test".

Which, also outputs "In test".

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