java - 为什么我不能在这里打印我的声明或任何内容？

Question

就像我的问题是，为什么它甚至无法打印里面的 hi - print 语句？

public class Processor {

      Random random = new Random();

class Process {
        int proId, prior, BurstLength;
    }

    ArrayList<Process> processList;
public static void main(String arg[]) {
}
    public Processor() {
    System.out.println("hi");

        processList = new ArrayList<>();

        for (int i = 0; i< 5 ; i++){
            Process newProcess = new Process();
            int temp;
            l1:while(true){
            int rand = 10 - 0;
                temp = random.nextInt(rand)+0;
                System.out.println(temp);
                for (Process p:processList)
                    if (p.proId == temp)
                        continue l1;

                break;
            }
            newProcess.proId = temp;
            newProcess.prior = (int)Math.round(Math.random()*9)+1;
            int range = 100 - 20 + 1;
            newProcess.BurstLength = random.nextInt(range) + 20;
            System.out.println("Process id\tPriority\tburst length");
             System.out.println(newProcess.proId+"\t"+newProcess.prior+"\t"+newProcess.BurstLength);
        }

             }
    }

Answer 1

您的main方法不包含任何内容。

public static void main(String arg[]) {
     // NOTHING HERE
}

因此，为了能够打印“hi”，您应该通过执行此操作在主方法中声明并初始化您的 Processor 类。

public static void main(String arg[]) {
     Processor p = new Processor();
}

输出:

hi
0
Process id  Priority    burst length
0   6   98
9
Process id  Priority    burst length
9   6   42
2
Process id  Priority    burst length
2   3   84
9
Process id  Priority    burst length
9   2   86
5
Process id  Priority    burst length
5   4   70