android使用CheckBox显示隐藏输入的密码

具体代码如下：

               final EditText et = (EditText)findViewById(R.id.tv);
		CheckBox cBox = (CheckBox)findViewById(R.id.box);
		cBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
			
			@Override
			public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
				if (isChecked) {
					et.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
				}else {
					et.setTransformationMethod(PasswordTransformationMethod.getInstance());
				}
			}
		});               final EditText e