Dialog(四)——报错Unable to add window -- token null is not for an application

/** * 问题描述: * 创建和显示对话框的时候报错 * Unable to add window -- token null is not for an application *  * 问题修正: * 不可使用Builder builder=new Builder(getApplicationContext()); * 应该使用Builder builder=new Builder(MainActivity.this); */private void showDialog(){ Dialog dialog; //正确 Builder builder=new Builder(MainActivity.this); //错误 //Builder builder=new Builder(getApplicationContext());         builder.setIcon(R.drawable.ic_launcher);         builder.setTitle(getResources().getString(R.string.dialog_title));         builder.setMessage(R.string.dialog_message);         builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int arg1) {}});         builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int arg1) {}});                  dialog=builder.create();         dialog.show();    }