java - Paper.init 未被调用

Question

我正在开发 Android Studio 应用程序，在最后的工作中，我实现了一个尝试通过蓝牙打印机打印内容的类。我使用 printooth 库，但是当需要执行此新 Activity 时，它给了我这个异常(exception):

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.testaapplication0209, PID: 11325
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.testaapplication0209/com.example.testaapplication0209.PrintActivity}: io.paperdb.PaperDbException: Paper.init is not called
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2768)

这是我的 PrintActivity:

public class PrintActivity extends AppCompatActivity implements PrintingCallback {

Printing printing;
Button btnPrint, btnPairUnpair;

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

private void initView() {

    btnPrint = findViewById(R.id.btnPrint);
    btnPairUnpair = findViewById(R.id.btnPairUnpair);

    if (printing != null)
        printing.setPrintingCallback(this);

    //event
    btnPairUnpair.setOnClickListener(view -> {
        if (Printooth.INSTANCE.hasPairedPrinter())
            Printooth.INSTANCE.removeCurrentPrinter();
        else {
            startActivityForResult(new Intent(PrintActivity.this, ScanningActivity.class), ScanningActivity.SCANNING_FOR_PRINTER);
            changePairAndUnpair();
        }
    });

    btnPrint.setOnClickListener(view -> {
        if (!Printooth.INSTANCE.hasPairedPrinter())
            startActivityForResult(new Intent(PrintActivity.this, ScanningActivity.class), ScanningActivity.SCANNING_FOR_PRINTER);
        else {
            printData();
        }
    });

    changePairAndUnpair();

}

private void printData() {
    ArrayList<Printable> printables = new ArrayList<>();
    printables.add(new RawPrintable.Builder(new byte[]{27,100,4}).build());

    //Add Text
    printables.add(new TextPrintable.Builder()
            .setText("Hello World").setCharacterCode(DefaultPrinter.Companion.getCHARCODE_PC1252())
            .setNewLinesAfter(1)
            .build()
    );

    //Custom Text
    printables.add(new TextPrintable.Builder()
    .setText("Hello World custom text")
    .setLineSpacing(DefaultPrinter.Companion.getLINE_SPACING_60())
    .setAlignment(DefaultPrinter.Companion.getALIGNMENT_CENTER())
    .setEmphasizedMode(DefaultPrinter.Companion.getEMPHASIZED_MODE_BOLD())
    .setUnderlined(DefaultPrinter.Companion.getUNDERLINED_MODE_ON())
    .setNewLinesAfter(1)
    .build());

    printing.print(printables);
}

private void changePairAndUnpair() {
    if (Printooth.INSTANCE.hasPairedPrinter()){
        btnPairUnpair.setText(new StringBuilder("Dissocia").append(Printooth.INSTANCE.getPairedPrinter().getName().toString()));
    } else {
        btnPairUnpair.setText("Associa Stampante");
    }
}

@Override
public void connectingWithPrinter() {
    Toast.makeText(this, "Connesione alla stampante", Toast.LENGTH_SHORT).show();
}

@Override
public void connectionFailed(String s) {
    Toast.makeText(this, "CFailerd: " +s, Toast.LENGTH_SHORT).show();
}

@Override
public void onError(String s) {
    Toast.makeText(this, "Error: " +s, Toast.LENGTH_SHORT).show();
}

@Override
public void onMessage(String s) {
    Toast.makeText(this, s, Toast.LENGTH_SHORT).show();
}

@Override
public void printingOrderSentSuccessfully() {
    Toast.makeText(this, "Ordine mandato alla stampante", Toast.LENGTH_SHORT).show();
}

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == ScanningActivity.SCANNING_FOR_PRINTER && resultCode == Activity.RESULT_OK)
        initPrinting();
    changePairAndUnpair();
}

private void initPrinting() {
    if(!Printooth.INSTANCE.hasPairedPrinter())
        printing = Printooth.INSTANCE.printer();
    if (printing != null)
        printing.setPrintingCallback(this);
}
}

在 ApplicationPrintActivity 中，我实例化了 printooth:

public class ApplicationPrintActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Printooth.INSTANCE.init(this);

}
}

Answer 1

不是 Android 开发人员，但这似乎更像是一种误解。

PrintActivity 直接扩展 AppCompatActivity，它不会“绕过”ApplicationPrintActivity#onCreate，因此 Paper.init 根本没有被调用。

编辑 PrintActivity#onCreate 以包含该调用。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Printooth.INSTANCE.init(this);

    setContentView(R.layout.activity_print);
    initView();
}