java: 无法取消引用long
时间: 2023-11-13 08:04:43 浏览: 64
在Java中,基本数据类型(primitive types)是按值传递的,它们不具备引用的概念。因此,你无法取消引用(dereference)一个long类型的变量,因为它不是一个引用类型。
如果你想取消引用一个long值,你可以通过将其赋值为0或者将其置为null(对应的是引用类型)来实现。但需要注意的是,这并不会真正释放内存,因为基本数据类型的变量直接存储在栈上,而不是堆中。
相关问题
java: incompatible types: possible lossy conversion from long to int
This error occurs when you try to assign a long value to an int variable, and the long value is too large to be represented as an int. In Java, long is a 64-bit signed integer, while int is a 32-bit signed integer. Therefore, if you try to assign a long value that is larger than the maximum value of an int (2147483647), the compiler will generate an error.
For example, the following code will generate the error "incompatible types: possible lossy conversion from long to int":
```
long myLong = 1234567890;
int myInt = myLong;
```
To fix this error, you can either change the type of the variable to long, or you can cast the long value to an int using the (int) operator. However, be aware that casting a long value to an int may result in data loss, as the long value may be too large to fit into the int variable.
java: 无法将类 java.util.Random中的方法 nextLong应用到给定类型;
这个错误通常是因为你在调用 `nextLong()` 方法时没有传入任何参数。在 `java.util.Random` 类中,`nextLong()` 方法有两个重载版本,一个是无参版本,一个是接收 `long` 类型参数的版本。如果你要生成一个随机的 `long` 类型整数,应该使用无参版本的 `nextLong()` 方法。
示例代码:
```java
import java.util.Random;
public class Example {
public static void main(String[] args) {
Random random = new Random();
long randomLong = random.nextLong();
System.out.println(randomLong);
}
}
```
如果你想生成一个指定范围内的随机 `long` 类型整数,可以使用 `nextLong(long bound)` 方法。这个方法会生成一个位于 `[0, bound)` 范围内的随机整数。
示例代码:
```java
import java.util.Random;
public class Example {
public static void main(String[] args) {
Random random = new Random();
long randomLong = random.nextLong(100);
System.out.println(randomLong);
}
}
```
这个示例会生成一个位于 `[0, 100)` 范围内的随机整数。