dialog()

protected void dialog() {
AlertDialog.Builder builder = new Builder(MainActivity.this);
builder.setMessage("确认退出吗？");
 builder.setTitle("提示");
 builder.setPositiveButton("确认", new OnClickListener() {
  public void onClick(DialogInterface dialog, int which) {
   dialog.dismiss();
   MainActivity.this.finish();}
 });
  builder.setNegativeButton("取消", new OnClickListener() {

  public void onClick(DialogInterface dialog, int which) {
   dialog.dismiss();}
 });
 builder.create().show();}