我想删除android中活动背板的数据

Question

在按下活动时删除数据此代码有效但应用程序崩溃

public void onBackPressed() { 

   File dir = context.getCacheDir();
   if(dir!= null && dir.isDirectory()){
   File[] children = dir.listFiles();
   if (children == null) {
  // Either dir does not exist or is not a directory
   } else {
   File temp;
   for (int i = 0; i < children.length; i++) {
    temp = children[i];
   temp.delete();

          }

   }}}

提前致谢。