Java中的 Long longValue() 方法

Java.lang.Long.longValue() 是Java Long 类的一个内置方法，它在转换后将这个Long 对象的值作为long 返回。
句法：

public long longValue()

参数：此方法不带任何参数。
返回值：该方法将返回该对象所代表的数值，转换为long类型。
例子：

Input: 5366623
Output: (Long) 5366623

Input: -6723887
Output: (Long) -6723887
Explanation:
When the number is passed in this object it will convert that 
to long and gives the value like,
Long lobject = new Long(5366623)
It will return 5366623 as long.

下面的程序说明了Java.lang.Long.longValue() 方法的工作原理。
程序 1：对于正数。

java

// Java program to illustrate the
// java.lang.Long.longValue() method
 
import java.lang.*;
 
public class Geek {
 
    public static void main(String[] args)
    {
 
        Long lobject = new Long(77387187);
 
        // It will return the value of this Long as a long
        long nl = lobject.longValue();
        System.out.println("The Value of nl as long is = " + nl);
 
        Long lobject2 = new Long(-6723887);
 
        // It will return the value of this Long as a long
        long nl2 = lobject2.longValue();
        System.out.println("The Value of nl2 as long is = " + nl2);
    }
}

输出：

The Value of nl as long is = 77387187
The Value of nl2 as long is = -6723887

方案 2：对于一个非常大的号码。
// 会产生编译时错误。

Java

// Java program to illustrate the
// java.lang.Long.longValue() method
import java.lang.*;
 
public class Geek {
 
    public static void main(String[] args)
    {
 
        Long lobject = new Long(97387717187);
 
        // Very large number will produce compile errors
        long nl = lobject.longValue();
        System.out.println("The Value of nl as long is = " + nl);
    }
}

输出：

prog.java:9: error: integer number too large: 97387717187
    Long lobject = new Long(97387717187);
                            ^
1 error

参考： https: Java/lang/Long.html#longValue()