synchronized一个Object对象是为了什么？

[中才德创]

public class RecycleViewList {
    static final String TAG = "RecycleViewList";

    private static final int INI_LIST_SIZE = 2;
    private final SparseArray<SoftReference<View>> mViewCache = new SparseArray<SoftReference<View>>(INI_LIST_SIZE);

    private Object syncLock = new Object();

    public void addToCache(int idx, View v) {
        synchronized (syncLock) {
            int size = mViewCache.size();
            Log.d(TAG, "addToCache: index="+idx+", size = "+size+", view="+v);
            mViewCache.put(idx, new SoftReference<View>(v));
        }
    }

    public View fetchCacheView(int idx) {
        synchronized (syncLock) {
            int size = mViewCache.size();            
            Log.d(TAG, "fetchCacheView: size = "+size);
            if ((idx>=size) || (idx<0)) {
                return null;
            }

            Log.d(TAG, "fetchCacheView: mViewCache.size() = "+mViewCache.size());
            SoftReference<View> cachedView = mViewCache.get(idx);
            Log.d(TAG, "fetchCacheView: cachedView= "+cachedView);

            if (cachedView != null) {
                View v = cachedView.get();
                Log.d(TAG, "fetchCacheView: cachedView.get()= "+v);
                if (v != null) {
                    Log.d(TAG, "fetchCacheView: leave with="+v);
                    return v;
                }
            }
        }
        return null;
    }

    public void clearCacheView() {
        synchronized (syncLock) {
            int size = mViewCache.size();
            Log.d(TAG, "clearCacheView: size = "+size);
            mViewCache.clear();
        }
    }
    
    public int getSize() {
        synchronized (syncLock) {
            int size = mViewCache.size();
            Log.d(TAG, "getSize: size = "+size);
            return size;
        }
    }
}

[媒体盒子]

用于多线程间的同步，当一个线程调用方法进入 synchronized (syncLock) { int size = mViewCache.size(); Log.d(TAG, "addToCache: index="+idx+", size = "+size+", view="+v); mViewCache.put(idx, new SoftReference<View>(v)); } 后其他线程调用该方法或去他含synchronized (syncLock) {的方法都必须wait 到 synchronized (syncLock) {}里面的代码执行完

[中才德创]

可是在静态类函数里，实现synchronized(this) {}却不行，报Cannot use this in a static context。 原因是因为，静态类函数隶属类，它没有this。这该如何呢？

public class FManager {
    /*
     * 函数介绍：保存log到日志文件
     * 输入参数：strLog字符串
     * 输出参数：无
     * 返回值  ：无
     */
	public static void saveLogSD(String strLog) {
		Log.v(TAG, "saveLogSD enter");

[zhujunhua2012]

静态函数，那就是应该用类级别的锁了，synchronized (FManager.class)；或者在类里面用一个static的变量（private static Object syncObj = new Object();），然后synchronized(syncObj)即可。