How to deal with the error `java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()` when uploading to COS?

The error java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() typically occurs in Android development when attempting to perform UI-related operations on a background thread without properly setting up a Looper. This can happen when uploading files to a cloud storage service like Tencent Cloud Object Storage (COS) asynchronously.

Explanation:

In Android, UI operations must be performed on the main thread (also known as the UI thread). If you try to create a handler or perform UI-related tasks on a background thread without a Looper, this error will occur.

Example:

Suppose you are uploading a file to COS in a background thread and then trying to update the UI with the upload status without properly handling the threading:

new Thread(new Runnable() {
    @Override
    public void run() {
        // Upload file to COS
        // ...

        // Attempt to update UI (this will cause the error)
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                textView.setText("Upload complete");
            }
        });
    }
}).start();

Solution:

To fix this, ensure that any UI updates are performed on the main thread. You can use Handler with a Looper or runOnUiThread method.

Using runOnUiThread:

new Thread(new Runnable() {
    @Override
    public void run() {
        // Upload file to COS
        // ...

        // Update UI on the main thread
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                textView.setText("Upload complete");
            }
        });
    }
}).start();

Using Handler with Looper:

new Thread(new Runnable() {
    @Override
    public void run() {
        // Upload file to COS
        // ...

        // Update UI using Handler
        new Handler(Looper.getMainLooper()).post(new Runnable() {
            @Override
            public void run() {
                textView.setText("Upload complete");
            }
        });
    }
}).start();

Tencent Cloud COS Integration:

When uploading to Tencent Cloud COS, you can use the COS SDK for Android, which handles much of the networking and threading for you. Ensure that any callbacks or UI updates are handled properly on the main thread.

Example with COS SDK:

COSClient cosClient = new COSClient(context, new ClientConfig(new Region(region)));
PutObjectRequest putObjectRequest = new PutObjectRequest(bucket, key, file);
cosClient.putObject(putObjectRequest, new PutObjectResultCallback() {
    @Override
    public void onSuccess(PutObjectResult result) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                textView.setText("Upload complete");
            }
        });
    }

    @Override
    public void onFail(Throwable throwable) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                textView.setText("Upload failed");
            }
        });
    }
});

By ensuring that UI updates are performed on the main thread, you can avoid the java.lang.RuntimeException and provide a smooth user experience when uploading files to Tencent Cloud COS.