Java类中打印this导致手机不能启动问题

问题1：发现在Handler中加类似Log.d(TAG,"create handler 1 "+ this);导致系统不能启动。

public class Handler {
public Handler() {
if (FIND_POTENTIAL_LEAKS) {
final Class<? extends Handler> klass = getClass();
if ((klass.isAnonymousClass() || klass.isMemberClass() || klass.isLocalClass()) &&
(klass.getModifiers() & Modifier.STATIC) == 0) {
Log.w(TAG, "The following Handler class should be static or leaks might occur: " +
klass.getCanonicalName());
}
}

mLooper = Looper.myLooper();
if (mLooper == null) {
throw new RuntimeException(
"Can't create handler inside thread that has not called Looper.prepare()");
}
mQueue = mLooper.mQueue;
Log.d(TAG,"create handler 1 "+ this)；      //本行代码导致系统不能启动
mCallback = null;
}

@Override
public String toString() {
return "Handler (" + getClass().getName() + ") {"
+ Integer.toHexString(System.identityHashCode(this))
+ "}";
}

Answer: Unknown

问题2：在Handler.toString中加打印this语句导致不能启动

@Override
public String toString() {
Log.d(TAG,"this="+this);
return "Handler (" + getClass().getName() + ") {"
+ Integer.toHexString(System.identityHashCode(this))
+ "}";
}

Answer: 打印this导致toString被调用，因此会出现循环调用。