java - 将方法(或 void)传递给 Java ArrayList

Question

我想知道是否有任何方法可以将“void”对象传递给 Java ArrayList。

例如，我想通过引用 list1.put(doThis()); 来将 void 对象“public void doThis()”传递给数组列表；

当将对方法的引用传递给数组列表对象时，我得到以下信息:

The method add(Object) in the type ArrayList<Object> is not applicable for the arguments (void)

我正在尝试创建一个类，它可以获取对其他类中方法的引用的 ArrayList，并迭代以在线程中执行这些方法。

package asWebRest.shared;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class ThreadRipper {

    private int maxThreads = 4;
    private int maxThreadsHost = 8;


    public void runProcess(String pString) {
        System.out.println(" --> Running [ "+pString+" ]");
        String s = null;
        String[] pArray = { "bash", "-c", pString };
        try { 
            Process p = new ProcessBuilder(pArray).start();
            BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
            BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
            while ((s = stdInput.readLine()) != null) { System.out.println(s); }
            while ((s = stdError.readLine()) != null) { System.out.println(s); }
            p.destroy();
        }
        catch (IOException e) { e.printStackTrace(); }
        System.out.flush();
    }

    public String runProcesses() {

        boolean pool = false;
        WebCommon wc = new WebCommon();
        ArrayList<Object> threadList = new ArrayList<Object>();
        threadList.add(runProcess("ls -l"));
        threadList.add(runProcess("ls -s"));
        threadList.add(runProcess("ls -al"));

        String runResults = "";
        int procLoop = 0;
        int inPool = 0;

        for(int i = 0; i < threadList.size(); i++) {            
            Object exTask = threadList.get(i);  
            if(!pool) {
                if(inPool < maxThreads) {
                    runResults += "Loop [" + procLoop + "] Thread [" + inPool + "]: " + exTask + "\n";
                    inPool++;
                } else {
                    procLoop++;
                    inPool = 0;
                }
            } else {
                runResults += "Pool Thread [" + inPool + "]: " + exTask + "\n";
                inPool++;
            }       
        }

        return runResults;

    }

    public int getMaxThreads() { return maxThreads; }
    public int getMaxThreadsHost() { return maxThreadsHost; }

}

Answer 1

您正在做的是添加 runProcess("ls -l") 的返回而不是引用runProcess ，并且自 runProcess不返回任何内容，Java 显示无法添加的错误 void到列表中。

您需要使用 Runnable 的列表s。

List<Runnable> processes = new ArrayList<Runnable>();

以这种方式将其添加到列表中，

processes.add(()->runProcess("ls -l"));

然后您可以使用进程列表执行您选择的任何操作，

for(Runnable process : processes) { 
   process.run();// You can other fancy stuff here.
   new Thread(process).start(); // eg : spawn in new thread.
}