如何使用线程更新进度条

Question

如何在Android中使用后台线程更新进度条？同时也需要更改进度条上的进度。请帮忙。

AndroidVogue

- user744881

Answer 1

我曾使用过 AsyncTask 来完成类似的任务。在 AsyncTask 中，有一个方法 onProgressUpdate(Integer)，你可以在每次迭代或者在 doInBackground() 执行期间某个进度完成时调用 publishProgress() 来触发它。

更多详情请参考文档。

- user456118

Answer 2

Thread t=new Thread()
{
public void run()
{
while(some condition)
{
sleep(1000);
Message myMessage = new Message();
myMessage.obj = "success";
handler.sendMessage(myMessage);
}
}
};


private Handler handler=new Handler()
    {
        @Override
        public void handleMessage(Message msg)
        {
            String result=(String)msg.obj;
                     if(result.equals("success")
                     {
                     //update progress bar here
                      }

                 }
        };

- Kakey

Answer 3

  // this is demonstrate how to update progress bar from a thread 
  private ProgressBar pgb;  //  is a progressBar named with pgb 
  private int progressBarStatus = 0;// is a variable named progressBarStatus and initialize by 0
  // in  onCreate  method find the ui component view horizontal prograssbar named progressBar2  


 public void load_bar(View view) // is a button OnClick
// and i am using a thread with for loop to demonstrate a task and variable progressBarStatus  as status 

  pgb = (ProgressBar) findViewById(R.id.progressBar2) ;// find view by id 

  pgb.setMax(100); // at this point we the maximum value of a progress bar to make it full like we make 100 pices of it 

  pgb.setProgress(0); // initialize the progress bar with 0 % progress

    // progress bar handler that update the status of progress bar . without handler we cant update progress bar from thread 

   progressBarbHandler.post(new Runnable() {
                public void run() {
                    pgb.setProgress(progressBarStatus);
                } 

- prashant00101

Answer 4

使用Handler，这个Handler将会更新进度条，你需要做的是： 1）从你的线程发送消息到Handler 2）在Handler中更新进度条。

- Jaiprakash Soni

---

有没有关于如何在从网络下载JSON对象时更新进度条的想法。这大约需要20秒钟，时间不固定，可能会更短。那么如何在进度条中增加进度呢？ - user744881

@AndroidVogue：你能提供一下你的代码样本吗？这样我就可以帮助你了。 - Jaiprakash Soni

在您的线程中还有一件事情可以做，那就是使用 yourActivity.this.runOnUiThread(new Runnable(){ public void run(){ /* 在此更新进度条 */ }})。 - Jaiprakash Soni

Answer 5

使用线程，您可以像这样完成它，只需在oncreate方法中调用函数。

public void loadProgressbar()
{
    progressBar.setMax(100);
    progressBar.setProgress(0);

    new Thread(new Runnable() {
        @Override
        public void run() {
            for (progress = 0; progress <= 100; progress++) {

                handler.post(new Runnable() {
                    public void run() {
                        progressBar.setProgress(progress);
                    }
                });


                try {
                    Thread.sleep(50);
                } catch (Exception ex) {
                }
            }
        }
    }).start();
}

- Hitesh Kushwah

Answer 6

private ProgressBar pgb;
private TextView textview;
private int progressBarStatus = 0;
private Handler progressBarbHandler = new Handler();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_next);
    pgb = (ProgressBar) findViewById(R.id.progressBar2) ;
}

public void load_bar(View view)
{
    pgb.setMax(100);
    pgb.setProgress(0);

    new Thread(new Runnable() {
        @Override
        public void run() {
            for (progressBarStatus = 0; progressBarStatus <= 100; progressBarStatus++) {

                progressBarbHandler.post(new Runnable() {
                    public void run() {
                        pgb.setProgress(progressBarStatus);
                    }
                });


                try {
                    Thread.sleep(50);
                } catch (Exception ex) {
                }
            }
        }
    }).start();
}

- prashant00101