Android提供了一个耳聋构造函数

Question

我的应用程序有问题。它已经在运行了，但现在我增加了蓝牙，从那以后页面不断崩溃。

所有10个类都有相同的结构，所有10个类都有相同的错误：

这个类应该提供一个默认的构造函数(没有参数的公共构造函数) (com.example.feuerwerkzndanlage.empfaenger_1_zuenden)

代码活动：

package com.example.feuerwerkzndanlage;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.util.concurrent.atomic.AtomicInteger;

public class empfaenger_1_zuenden extends AppCompatActivity{

    private final ConnectedThread mConnectedThread; // bluetooth background worker thread to send and receive data

    public empfaenger_1_zuenden(ConnectedThread mConnectedThread){
        this.mConnectedThread = mConnectedThread;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.empfaenger_1_zuenden);

        Context context = getApplicationContext();
        CharSequence back_txt = "Zurück!";
        CharSequence rot_txt = "Zünden!";
        CharSequence gruen_txt = "Reset!";
        int a = 0;
        AtomicInteger b = new AtomicInteger(0);
        AtomicInteger c = new AtomicInteger(0);
        AtomicInteger d = new AtomicInteger(0);
        AtomicInteger e = new AtomicInteger(0);
        AtomicInteger f = new AtomicInteger(0);
        int duration = Toast.LENGTH_SHORT;

        ImageView back = findViewById(R.id.back);
        Button zuenden1_1 = findViewById(R.id.btn_zuenden1_1);
        Button zuenden1_2 = findViewById(R.id.btn_zuenden1_2);
        Button zuenden1_3 = findViewById(R.id.btn_zuenden1_3);
        Button zuenden1_4 = findViewById(R.id.btn_zuenden1_4);
        Button zuenden1_5 = findViewById(R.id.btn_zuenden1_5);

        Button ruecksetzen = findViewById(R.id.btn_ruecksetzen);

        ImageView kanal_1_1 = findViewById(R.id.kanal1_1);
        ImageView kanal_1_2 = findViewById(R.id.kanal1_2);
        ImageView kanal_1_3 = findViewById(R.id.kanal1_3);
        ImageView kanal_1_4 = findViewById(R.id.kanal1_4);
        ImageView kanal_1_5 = findViewById(R.id.kanal1_5);

        back.setOnClickListener(view -> {
            Toast.makeText(context, back_txt, duration).show();
            startActivity(new Intent(empfaenger_1_zuenden.this, zuenden.class));
        });

        ruecksetzen.setOnClickListener(view -> {
            Toast.makeText(context, gruen_txt, duration).show();
            kanal_1_1.setImageResource(R.drawable.kanal_gruen);
            kanal_1_2.setImageResource(R.drawable.kanal_gruen);
            kanal_1_3.setImageResource(R.drawable.kanal_gruen);
            kanal_1_4.setImageResource(R.drawable.kanal_gruen);
            kanal_1_5.setImageResource(R.drawable.kanal_gruen);
            b.set(a + 1);
            c.set(a + 1);
            d.set(a + 1);
            e.set(a + 1);
            f.set(a + 1);
        });

        zuenden1_1.setOnClickListener(view -> {
            if (b.get() == 1) {
                Toast.makeText(context, rot_txt, duration).show();
                kanal_1_1.setImageResource(R.drawable.kanal_rot);
                b.set(0);

                if(mConnectedThread != null) //First check to make sure thread created
                    mConnectedThread.write("Kanal_1_1_Z");
            }
        });

        zuenden1_2.setOnClickListener(view -> {
            if (c.get() == 1) {
                Toast.makeText(context, rot_txt, duration).show();
                kanal_1_2.setImageResource(R.drawable.kanal_rot);
                c.set(0);

                if(mConnectedThread != null) //First check to make sure thread created
                    mConnectedThread.write("Kanal_1_2_Z");
            }
        });

        zuenden1_3.setOnClickListener(view -> {
            if (d.get() == 1) {
                Toast.makeText(context, rot_txt, duration).show();
                kanal_1_3.setImageResource(R.drawable.kanal_rot);
                d.set(0);

                if(mConnectedThread != null) //First check to make sure thread created
                    mConnectedThread.write("Kanal_1_3_Z");
            }
        });

        zuenden1_4.setOnClickListener(view -> {
            if (e.get() == 1) {
                Toast.makeText(context, rot_txt, duration).show();
                kanal_1_4.setImageResource(R.drawable.kanal_rot);
                e.set(0);

                if(mConnectedThread != null) //First check to make sure thread created
                    mConnectedThread.write("Kanal_1_4_Z");
            }
        });

        zuenden1_5.setOnClickListener(view -> {
            if (f.get() == 1) {
                Toast.makeText(context, rot_txt, duration).show();
                kanal_1_5.setImageResource(R.drawable.kanal_rot);
                f.set(0);

                if(mConnectedThread != null) //First check to make sure thread created
                    mConnectedThread.write("Kanal_1_5_Z");
            }
        });
    }
}

代码宣言

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.feuerwerkzndanlage">

    <uses-feature android:name="android.hardware.bluetooth" />
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />

    <permission android:name="android.permission.BLUETOOTH" android:label="BLUETOOTH" />
    <permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <permission android:name="android.permission.BLUETOOTH_SCAN" />

    <uses-permission android:name="android.permission.USE_BIOMETRIC" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/logo"
        android:label="@string/app_name"
        android:roundIcon="@drawable/logo"
        android:supportsRtl="true"
        android:theme="@style/Theme.Feuerwerkzündanlage">
        <activity
            android:name=".Musik_Auswahl"
            android:exported="false" />
        <activity
            android:name=".Main_Bluetooth"
            android:exported="false" />
        <activity
            android:name=".inArbeit"
            android:exported="false" />
        <activity
            android:name=".zeit_laden_1"
            android:exported="false" />
        <activity
            android:name=".zeit_speichern_auswahl"
            android:exported="false" />
        <activity
            android:name=".zeit_ruecksetzen"
            android:exported="false" />
        <activity
            android:name=".zeit_speichern_1"
            android:exported="false" />
        <activity
            android:name=".empfaenger_1"
            android:exported="false" />
        <activity
            android:name=".empfaenger_2"
            android:exported="false" />
        <activity
            android:name=".empfaenger_3"
            android:exported="false" />
        <activity
            android:name=".empfaenger_4"
            android:exported="false" />
        <activity
            android:name=".empfaenger_5"
            android:exported="false" />
        <activity
            android:name=".empfaenger_6"
            android:exported="false" />
        <activity
            android:name=".empfaenger_7"
            android:exported="false" />
        <activity
            android:name=".empfaenger_8"
            android:exported="false" />
        <activity
            android:name=".empfaenger_9"
            android:exported="false" />
        <activity
            android:name=".empfaenger_10"
            android:exported="false" />
        <activity
            android:name=".empfaenger_1_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_2_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_3_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_4_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_5_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_6_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_7_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_8_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_9_zuenden"
            android:exported="false" />
        <activity
            android:name=".empfaenger_10_zuenden"
            android:exported="false" />
        <activity
            android:name=".Achtung_Scharf"
            android:exported="false" />
        <activity
            android:name=".Test"
            android:exported="false" />
        <activity
            android:name=".Biometric_Authentication"
            android:exported="false" />
        <activity
            android:name=".test_arm"
            android:exported="false" />
        <activity
            android:name=".vorschlaege"
            android:exported="false" />
        <activity
            android:name=".gesp_feuerwerke"
            android:exported="false" />
        <activity
            android:name=".Auswahl_Planer"
            android:exported="false" />
        <activity
            android:name=".Planer_1"
            android:exported="false" />
        <activity
            android:name=".Planer_2"
            android:exported="false" />
        <activity
            android:name=".Planer_3"
            android:exported="false" />
        <activity
            android:name=".Planer_4"
            android:exported="false" />
        <activity
            android:name=".Planer_5"
            android:exported="false" />
        <activity
            android:name=".Planer_6"
            android:exported="false" />
        <activity
            android:name=".Planer_7"
            android:exported="false" />
        <activity
            android:name=".Planer_8"
            android:exported="false" />
        <activity
            android:name=".Planer_9"
            android:exported="false" />
        <activity
            android:name=".Planer_10"
            android:exported="false" />
        <activity
            android:name=".zuenden"
            android:exported="false" />
        <activity
            android:name=".Sidebar"
            android:exported="false" />
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

因为您使用关键字final，所以

中的私有ConnectedThread mConnectedThread；// final关键字是一个常量。

1. --没有重新命令为活动创建构造函数，不需要新实例化它。activitys之间的通信是通过使用startActivityForResult().

或startActivity()

意图it =新意图(FirstActivity.this，SecondActivity.class)；it.putExtra(" data "，"Hi is FirstAcitvity")；//如果需要将一些数据传递给SecondAcrivity startActivity(it)；

1. ，蓝牙组件，您可以创建类似于BluetoothManager.java的东西，并从IntentService (线程安全)扩展。

公共类BluetoothMnager扩展了IntentService {公共静态最终字符串RESULT_RECEIVER = "RESULT_RECEIVER"；公共静态最终字符串RESPONSE_CODE = 200；//做任何您需要的事情:覆盖受保护的无效onHandleIntent(@Nullable意图){ //声明结果接收方ResultReceiver receiver = intent.getParcelableExtra(RESULT_RECEIVER)；String action = intent.getAction()；Bundle b=新绑定()；b.putString(“响应”，"data")；receiver.send(RESPONSE_CODE，b)；}

//活动方面

公共MainActivity扩展.{@覆盖受保护的无效onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState)；Button bt =新按钮(此)；bt.setText(“发送服务”)；bt.setOnClickListener(新View.OnClickListener() {@覆盖公共void (视图)){IN意图it =新意图(MainActivity.this，BluetoothMnager.class)；it.putExtra(BluetoothMnager.RESULT_RECEIVER，mReceiver)；startService(it)；)；

@重载受保护的onResume(){ //声明a ResultReceiver mReceiver =新的ResultReceiver(新的Handler()){ @Override void onReceiveResult(int resultCode，Bundle resultData) { super.onReceiveResult (resultCode，resultData)；if (resultCode == 200){ String response = resultData.getString("response")；Log.d(标记，“响应：+响应”)；Toast.makeText(MainActivity.this，response，Toast.LENGTH_SHORT).show()；}