用静态方法创建Java多线程

Question

我完全不熟悉Java（但我对C++有一些知识），并且无法在现有主题上找到答案。

我有一个包含静态方法的公共类。这个创建了多个线程，每个线程都实例化这个类的一个实例，每个实例都有一个阻塞处理。

我尝试添加一个Runnable为这个类的一个领域，但我是一个有点困惑如何正确做...

public class MyClass extends java.awt.Frame { 
    String myString1; 
    String myString2; 
    String myString3; 
    private ActionListener aL; 
    private volatile boolean boolRunning; 

    public Runnable r = new Runnable(){ 
     @Override 
     public void run() { 
      MyClass q = new MyClass(MyClass.this); 
      synchronized (this) { 
       MyClass.this.notify(); 
      } 
     } 
    } 

    private MyClass(String toParse){ 
     String[] parsed = toParse.split(":"); 
     this.myString1 = parsed[0]; 
     this.myString2 = parsed[1]; 
     this.myString3 = parsed[2]; 
     instantiateFrame(); 
    } 

    public void instantiateFrame(){ 
     this.setBounds(...); 
     this.setLayout(...); 
     Button btn = new Button("Submit"); 
     [...] 
     this.aListener = new ActionListener(){ 
      @Override 
      public void actionPerformed(ActionEvent e){ 
       /************************/ 
       /* Treatment hear  */ 
       /* Increment static Var */ 
       /************************/ 
       synchronized (MyClass.this){ 
        boolRunning = true; 
        MyClass.this.notify(); 
       } 
       MyClass.this.dispose(); 
      } 
     }; 
     btn.addActionListener(aL); 
     this.add(btn); 
     this.setVisible(true); 
     /* Wait for btn clicked */ 
     /* Blocking method */ 
     synchronized(this) { 
      try { 
       this.wait(); 
       boolRunning = true; 
      } catch (InterruptedException ex) { 
       Logger.getLogger(MyClass.class.getName()).log(Level.SEVERE, null, ex); 
      } 
     } 
    } 

    public static int startThreads(String[] toParseTable){ 
     Thread[] t = new Thread[toParseTable.length]; 
     for (int i = 0; i < toParseTable.length; i++) { 
      t[i] = new Thread(MyClass.r);  // Not compiling : Non static variable "r" cannot be referenced from a static context 
      t[i].start(); 
     } 
     /* Wait for all Threads */ 
     for (Thread th : t) { 
      try { 
       th.join(); 
      } catch (InterruptedException ex) { 
       Logger.getLogger(MyClass.class.getName()).log(Level.SEVERE, null, ex); 
      } 
     } 
     return MyClass.someStaticVar; 
    } 

    public static void main(String[] args) { 
     String[] someStrings = {"...:...:...", 
           "...:...:...", 
           "...:...:..."}; 
     try { 
      System.out.println(MyClass.startThreads(someStrings)); 
     } catch (CustomThrownException e) { 
      System.err.println(e.getMessage()); 
     } 
    } 
} 

Answer 1

您试图访问一个实例变量（即是一个属于一个对象的变量）在一个方法中不属于一个实例对象，而是属于这个类。 static函数和变量是全局类，但不能访问实例中的变量，因为没有隐式this。

class Foo { 
    private int value = 2; 
    private static int woz = 6; 

    public void foo() { 
    System.out.println(value); // ok, access instance variable in instance method with implicit this object 
    System.out.println(woz); // ok, access 'class global' variable 
    } 


    public static void bar() { // is a 'class' method, not an instance method 
    System.out.println(value); // can't because there is no 'this' object here 
    System.out.println(woz); // ok, access 'class global' variable 
}