Question

我是android java开发的新手。我尝试实现QR-Code-Scanner。我找到了一个很好的类来实现这个功能。但我想分开这堂课。

我有两节课。

public class MainActivity extends AppCompatActivity {
public class QrCodeScanner extends Activity

从我想要调用方法的MainActivity

public void scanQR(View v)

这怎么办？

我无法从QrCodeScanner类创建实例。

提前致谢！

public class QrCodeScanner extends Activity {

static final String ACTION_SCAN = "com.google.zxing.client.android.SCAN";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //set the main content layout of the Activity
    setContentView(R.layout.activity_main);
}

//product qr code mode
public void scanQR(View v) {
    try {
        //start the scanning activity from the com.google.zxing.client.android.SCAN intent
        Intent intent = new Intent(ACTION_SCAN);
        intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
        startActivityForResult(intent, 0);
    } catch (ActivityNotFoundException anfe) {
        //on catch, show the download dialog
        showDialog(QrCodeScanner.this, "No Scanner Found", "Download a scanner code activity?", "Yes", "No").show();
    }
}

//alert dialog for downloadDialog
private static AlertDialog showDialog(final Activity act, CharSequence title, CharSequence message, CharSequence buttonYes, CharSequence buttonNo) {
    AlertDialog.Builder downloadDialog = new AlertDialog.Builder(act);
    downloadDialog.setTitle(title);
    downloadDialog.setMessage(message);
    downloadDialog.setPositiveButton(buttonYes, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialogInterface, int i) {
            Uri uri = Uri.parse("market://search?q=pname:" + "com.google.zxing.client.android");
            Intent intent = new Intent(Intent.ACTION_VIEW, uri);
            try {
                act.startActivity(intent);
            } catch (ActivityNotFoundException anfe) {

            }
        }
    });
    downloadDialog.setNegativeButton(buttonNo, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialogInterface, int i) {
        }
    });
    return downloadDialog.show();
}

//on ActivityResult method
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    if (requestCode == 0) {
        if (resultCode == RESULT_OK) {
            //get the extras that are returned from the intent
            String contents = intent.getStringExtra("SCAN_RESULT");
            String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
        }
    }
}
}

Answer 1

你的方法实际上只是为另一个活动开始一个意图，所以你为什么不在另一个类中创建这个方法，所以你可以从任何有上下文参数的地方调用它：

 //product qr code mode
public void scanQR(View v, Context ctx) {
    try {
        //start the scanning activity from the com.google.zxing.client.android.SCAN intent
        Intent intent = new Intent(ACTION_SCAN);
        intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
        ((Activity) ctx).startActivityForResult(intent, 0);
    } catch (ActivityNotFoundException anfe) {
        //on catch, show the download dialog
    }
}

扫描结果应该传递给持有上下文的活动。

Android Java - 使用其他activityClass中的方法

1 个答案: