requestFeature() must be called before adding content错误处理

练习ProgressBar案例时，模拟器运行Activity，提示如下错误：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.processbar/com.example.processbar.MainActivity}: android.util.AndroidRuntimeException: requestFeature() must be called before adding content

代码：

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
requestWindowFeature(Window.FEATURE_PROGRESS);

解决办法：

将requestWindowFeature方法放在super.onCreate(savedInstanceState)后面。