Android重写返回键处理事件

@Override
public void onBackPressed() {
Dialog dialog = new AlertDialog.Builder(this)
.setTitle("信息提示")
.setMessage("确定要退出系统吗?")
.setPositiveButton("确定", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        finish();
    }
})
.setNeutralButton("取消", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        return;
    }
})
.create();
dialog.show();
}