How to I launch an activity with an Intent and pass a variable in the new activity?

So right now I'm using the zxing barcode scanner in my app. Here is example code(generic):

if(position == 0){
            Intent intent = new Intent("com.google.zxing.client.android.SCAN");
           开发者_C百科 intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
            startActivityForResult(intent, 0);


        }

public void onActivityResult(int requestCode, int resultCode, Intent intent) {
        if (requestCode == 0) {
            if (resultCode == RESULT_OK) {
                contents = intent.getStringExtra("SCAN_RESULT");
                format = intent.getStringExtra("SCAN_RESULT_FORMAT");
                // Handle successful scan
                Intent i = new Intent(Main.this, BarcodeScanner.class);
                startActivity(i);
            } else if (resultCode == RESULT_CANCELED) {
                // Handle cancel
            }
        }
    }

So when launching the BarcodeScanner.class, I also want to pass contents into it. How would I go about doing that?

Use Bundle inside intents to pass data from one activity to the other. In your case, you would have to do something like -

        Intent intent = new Intent(Main.this,BarcodeScanner.class);

        //load the intent with a key "content" and assign it's value to content            
        intent.putExtra("content",contents);

        //launch the BarcodeScanner activity and send the intent along with it
        //note that content  is passed in as well             
        startActivity(intent);

The information is stored in a 'Bundle' object that lives inside the Intent - the Bundle is created when you call the putExtras() method of the Intent object

The same way you passed "SCAN_MODE" to the other activity, by calling putExtra("some key", contents) before calling startActivity(), and then inside BarcodeScanner call this.getIntent().getStringExtra("some key")