我试图让这个程序仅在命令行之外运行(在本例中为命令提示符)，但是当我创建 .jar 时，我不断收到此错误:
Expception in thread "main" java.lang.UnsupportedClassVersionError: Exponentiation: Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: Exponentiation. Program will exit.
程序是:
//import scanner for user input
import java.util.Scanner;
public class Exponentiation
{
static long values[]; //array of values to be computed
static long output[]; //array of computed values
static int numberExp; //number times the experiment is run
static int currentExp = 1; //current time the experiment is running
//main method
public static void main(String [] args)
{
//run initial setup and random generating
setup();
//run the interative and recursive components until the user specified number of experiments
for (currentExp = 1; currentExp <= numberExp; currentExp++)
{
iterative();
recursive();
}
} //close main method
//runs the trail iteratively
public static void iterative()
{
//create variables for time
long initialTime;
long endTime;
long diffTime;
//record initial time
initialTime = System.nanoTime();
//for every value exponetiate
for (int counter = 1; counter <= values[0]; counter++)
{
//raise every value by its opposing value in the array
output[counter] = values[counter]^values[(int)values[0] + 1 - counter];
}
//recourd end time
endTime = System.nanoTime();
//calculate the difference
diffTime = endTime - initialTime;
//output time values
System.out.println();
System.out.println("Experiment " + currentExp + " Iterative:");
System.out.println(initialTime);
System.out.println(endTime);
System.out.println(diffTime);
} //close iterative method
//runs the trial recursively
public static void recursive()
{
//create variables for time
long initialTime;
long endTime;
long diffTime;
//record initial time
initialTime = System.nanoTime();
//for every value exponetiate
for (int counter = 1; counter <= values[0]; counter++)
{
//raise every value by its opposing value in the array using the recursive method
output[counter] = recursiveExpo(values[counter],values[(int)values[0] + 1 - counter]);
}
//recourd end time
endTime = System.nanoTime();
//calculate the difference
diffTime = endTime - initialTime;
//output time values
System.out.println();
System.out.println("Experiment " + currentExp + " Recursive:");
System.out.println(initialTime);
System.out.println(endTime);
System.out.println(diffTime);
} //close recursive method
public static long recursiveExpo(long base, long expo) {
if (expo == 0) {
return 1;
} else {
return base * recursiveExpo(base, expo - 1);
}
} //close recursiveExpo
//setup method - runs all setup isolated from the main program
public static void setup()
{
int lowRange; //lowest possible random value
int highRange; //highest possible random value
int numOfTrials; //number of trials/random numbers to be generated
//create scanner for user input
Scanner input = new Scanner( System.in );
//runs the random number generator until a good assortment is found
for (boolean goodRandom = false; goodRandom == false;)
{
//clear values[], just in case
values = null;
System.out.println("This is the program for Iterative Exponetiation");
System.out.println("Enter your prefered range of numbers");
System.out.println("Lowest possible number");
lowRange = input.nextInt(); //store min random number
System.out.println("Highest possible number");
highRange = input.nextInt(); //store max random number
System.out.println("Number of trials");
numOfTrials = input.nextInt(); //store number of trials
System.out.println("How many times should the experiment be run?");
numberExp = input.nextInt(); //store number of experiments
//create array of the correct size and store the size in the 0th element
values = new long[numOfTrials+1];
values[0] = numOfTrials;
//make the output array the same lenght
output = new long[numOfTrials+1];
//generate random values for each element until the numOfTrials is reached
for (int counter = 1; counter <= numOfTrials; counter++)
{
values[counter] = (int)(Math.random()*(highRange)) + lowRange;
}
//create output and concatinate numbers
for (int counter = 0; counter <= values[0]; counter++)
{
//add a line break every tenth number
//and output the values[]
if ((int)(counter/10) == (((double)counter)/10))
{
System.out.println(values[counter] + " ");
} else {
System.out.print(values[counter] + " ");
}
}
System.out.println("Enter 1 to use these values or 0 for new ones");
//regenerate or not?
if (input.nextInt() == 1)
{
goodRandom = true; //continue on the actual test
}
} //close number-generator loop
} //close setup method
} //close Expo class
我认为我的扫描仪出了问题，但我不确定是什么。
最佳答案
当您使用 jdk 7+ 编译此代码时，您实际上是使用 java <=6 运行它。 如果你看here您会看到 51.0 是 java 7，事实上它不受支持意味着您的类路径上的 java 较旧。
尝试在命令行上运行java -version来验证并修复您的路径
关于java - 在命令提示符下使用 Java.util.scanner，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17819417/