Android 忽略 finish()

Question

我在 android 上遇到条形码扫描器问题。我尝试构建一个应用程序，其中有一个按钮，它运行新的 activity，扫描代码，然后使用扫描的代码返回到 MainActivity。但是...

这是 MainActivity 的代码:

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
    private DrawerLayout drawer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        drawer = findViewById(R.id.drawer_layout);

        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new ScanFragment()).commit();
            navigationView.setCheckedItem(R.id.nav_scan);
        }
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
        switch (menuItem.getItemId()) {
            case R.id.nav_scan:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new ScanFragment()).commit();
                break;
            case R.id.nav_okruh:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new OkruhFragment()).commit();
                break;
            case R.id.nav_kzavozu:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new KZavozuFragment()).commit();
                break;
            case R.id.nav_zprava:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new ZpravaFragment()).commit();
                break;
        }
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

    @Override
    public void onBackPressed() {
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }
}

fragments是抽屉布局。每个片段都用于另一个动作，在第一个片段中，有一个 button:

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import com.google.android.gms.vision.barcode.BarcodeDetector;

import static com.google.android.gms.vision.barcode.Barcode.ALL_FORMATS;

public class ScanFragment extends Fragment {

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_scan, container, false);
        Button button = (Button) view.findViewById(R.id.button2);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(getActivity(), ScanOkno.class);
                startActivity(intent);
            }
        });
        return view;
    }
}

这里是扫描仪的 Activity，代号为 ScanOkno.class:

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseArray;
import android.widget.Toast;

import com.google.android.gms.vision.barcode.Barcode;

import java.util.List;

import info.androidhive.barcode.BarcodeReader;

public class ScanOkno extends AppCompatActivity implements BarcodeReader.BarcodeReaderListener {

    private BarcodeReader barcodeReader;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_scan_okno);
        barcodeReader = (BarcodeReader) getSupportFragmentManager().findFragmentById(R.id.barcode_fragment);
    }

    @Override
    public void onScanned(Barcode barcode) {
        // play beep sound
        barcodeReader.playBeep();
        barcodeReader.pauseScanning();
        finish();
    }

    @Override
    public void onScannedMultiple(List<Barcode> list) {

    }

    @Override
    public void onBitmapScanned(SparseArray<Barcode> sparseArray) {

    }

    @Override
    public void onScanError(String s) {

    }

    @Override
    public void onCameraPermissionDenied() {
        Toast.makeText(getApplicationContext(), "Camera permission denied!", Toast.LENGTH_LONG).show();
    }
}

我的问题是finish()； onScanned() 部分代码中的函数，因为它不会关闭 activity ScanOkno。 Window 显示代码周围的框架，如果扫描，它会发出哔哔声，然后我暂停扫描，我想结束 activity，但我找不到，为什么它不想关闭并继续回到 MainActivity.

我也不知道如何将扫描的代码传输到主程序 activity，但我认为可以使用全局变量，例如：final code = barcode.rawValue;

感谢您的回复。

Answer 1

更新

谢谢指正@Gabe Sechan

你MainActivity打电话给ScanOkno到startActivityForResult:

startActivityForResult(ScanOkno.class, REQUEST_CODE);

并将结果发送回 MainActivity：

Intent resultIntent = new Intent();
// passing data back to result
resultIntent.putExtra("code", "some_string");
setResult(Activity.RESULT_OK, resultIntent);
finish();

并接收结果：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        String code = data.getStringExtra("code");
    } 
}

Answer 2

没有足够的代表评论，但是这个方法是在主线程上调用的吗？

@Override
public void onScanned(Barcode barcode) {
    // play beep sound
    barcodeReader.playBeep();
    barcodeReader.pauseScanning();
    finish();
}

如果从后台线程触发，finish() 可能会被忽略（我似乎找不到任何文档说明如果从其他地方调用它会发生什么。）

Android 忽略 finish()

Android ignores finish()

android

barcode-scanner

android-activity