在Android中进行大量计算时如何显示加载屏幕? [英] How to display a loading screen while doing heavy computing in Android?

问题描述

我正在研究一个程序，该程序会在用户电话中搜索某个日期，该日期大约需要2-3秒.在计算时，我想显示一个加载屏幕，以便用户知道确实正在发生某些事情.但是，当我尝试在计算之前显示加载屏幕时，屏幕上什么都没有显示.

I am working on a program that searches the users phone for some date, which takes about 2-3 seconds. While it's computing I want to display a loading screen, so the user knows something indeed is happening. However, when I try to display a loading screen before the computations, nothing is displayed on the screen.

这就是我所拥有的:

        ProgressDialog loading= new ProgressDialog(this);
        loading.setTitle("Loading");
        loading.setMessage("Please wait...");
        loading.show();

       //search stuff
        loading.dismiss();

除此之外，我还尝试将ProgressDialog放入如下所示的线程中，

In addition to this, I have tried putting the ProgressDialog in a thread like the following,

new Thread(new Runnable(){
            public void run(){
              ProgressDialog loading= new ProgressDialog(this);//error here for "this"
              loading.setTitle("Loading");
              loading.setMessage("Please wait...");
              loading.show();
            }
        });
//search stuff

但是由于"this"关键字而失败，我相信是因为它指的是Activity而不是常规类，但是我可能错了...

but it fails due to the "this" keyword, I believe because its referring to an Activity and not a regular class, but I could be wrong...

如何使ProgressDialog正确显示?

How can I get the ProgressDialog to display properly?

推荐答案

尝试以这种方式处理

mProgressDialog = ProgressDialog.show(this, "Please wait","Long operation starts...", true);
        new Thread() {
            @Override
            public void run() {

               //Do long operation stuff here search stuff

                try {

                    // code runs in a thread
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            mProgressDialog.dismiss();
                        }
                    });
                } catch (final Exception ex) {

                }
            }
        }.start();

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