Java线程_05

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被替换掉的同步

继承体系结构下父类的某个声明为同步的方法是可以被更加具体的子类覆盖并声明为非同步。

示例

/** * 父类的synchronized方法可以在子类中改变为非synchronized方法 * @author WangYanCheng * @version 2012-11-12 */public class SynExtends {    public static void main(String[] args) {        ParentClass pcInst = new SubClass();//new ParentClass();        Set<Integer> resultSets =Collections.synchronizedSet(new TreeSet<Integer>());        createThread(pcInst, resultSets);        createThread(pcInst, resultSets);        createThread(pcInst, resultSets);        createThread(pcInst, resultSets);    }    public static void createThread(final ParentClass pcInst, final Set<Integer> valueSet) {        new Thread(new Runnable() {            public void run() {                while (true) {                    Integer tmpI = pcInst.doWork();                    if (!valueSet.add(tmpI)) {                        throw new IllegalStateException("数据状态不正确，出现重复：".concat(tmpI.toString()));                    }                    try {                        Thread.sleep(100);                    } catch (InterruptedException ie) {                        ie.printStackTrace();                    }                }            }        }).start();    }}class ParentClass {    private volatile int index;    public synchronized Integer doWork() {        return index++;    }}class SubClass extends ParentClass {    private int index;    @Override    public Integer doWork() {        return index++;    }}