Android 避免2个相互影响的 EditText 死循环

两个EditText同时设置TextChangedListener后，会使程序进入死循环，解决方法如下：

		etExchangeRateEn = (EditText) findViewById(R.id.etExchangeRateEn);
		etExchangeRateCn = (EditText) findViewById(R.id.etExchangeRateCn);

		twEN = new TextWatcher()
		{

			@Override
			public void afterTextChanged(Editable s)
			{
				etExchangeRateCn.addTextChangedListener(twCN);
			}

			@Override
			public void beforeTextChanged(CharSequence s, int start, int count, int after)
			{

			}

			@Override
			public void onTextChanged(CharSequence s, int start, int before, int count)
			{

				etExchangeRateCn.setText( "CN");

			}

		};

		twCN = new TextWatcher()
		{

			@Override
			public void afterTextChanged(Editable s)
			{
				etExchangeRateEn.addTextChangedListener(twEN);

			}

			@Override
			public void beforeTextChanged(CharSequence s, int start, int count, int after)
			{
			}

			@Override
			public void onTextChanged(CharSequence s, int start, int before, int count)
			{

				etExchangeRateEn.setText("EN");

			}
		};
		etExchangeRateEn.addTextChangedListener(twEN);
		etExchangeRateCn.addTextChangedListener(twCN);