我的应用程序在android studio模拟器中停止工作

Question

这里是android manifest的代码，这里是运行模拟器时调试错误消息的链接。当我点击Run或debug按钮时，模拟器出现了，但应用程序显示“AppName停止工作”，我感觉问题不是在android Manifest.xml中，就是在Java代码中。在android清单中，错误代码位于
“android:name=”com.example.quiz.FullScreenActivity“”

错误消息为“该类应提供默认构造函数（没有参数的公共构造函数）（com.example.quiz.FullScreenActivity）”

错误信息

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/quiz"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Quiz">
        <activity
            android:name="com.example.quiz.FullscreenActivity"
            android:configChanges="orientation|keyboardHidden|screenSize"
            android:label="@string/app_name"
            android:theme="@style/Theme.Quiz.Fullscreen">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

这是Java的密码。

package com.example.quiz;

import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import com.google.android.material.snackbar.Snackbar;
import java.util.Objects;

public class FullscreenActivity extends AppCompatActivity {
    Button btn1;
    Button btn2;
    Button btn3;
    Button btn4;
    TextView txt1;
    TextView txt2;
    TextView txt3;
    View mainView;
    Snackbar snackbarCorrect;
    Snackbar snackbarWrong;
    private final Object FirstFragment;

    public FullscreenActivity(Object firstFragment) {
        FirstFragment = firstFragment;
    }


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Objects.requireNonNull(getSupportActionBar()).hide();
        setContentView(R.layout.activity_fullscreen);

        if (savedInstanceState == null){
            getSupportFragmentManager().beginTransaction().
                    setReorderingAllowed(true).
                    add(R.id.Fragment, (Fragment) FirstFragment, null).
                    commit();
        }
        btn1 = findViewById(R.id.choice1);
        btn2 = findViewById(R.id.choice2);
        btn3 = findViewById(R.id.choice3);
        btn4 = findViewById(R.id.choice4);
        mainView = findViewById(R.id.matchmaker);
        txt1 = findViewById(R.id.textView1);
        txt2 = findViewById(R.id.TextView2);
        txt3 = findViewById(R.id.TextView3);
        //READ ABOUT EVENT HANDLERS , Listeners
        snackbarCorrect = Snackbar.make(mainView, "Well done!", 1000);
        snackbarWrong = Snackbar.make(mainView, "Try again!", 1000);
        mainView.setOnClickListener(v -> mainView.setBackgroundColor(Color.BLUE));

        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //txt1.setText("Try again");
                snackbarWrong.show();
            }
        });

        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //txt2.setText("Well done that\nis correct");
                snackbarCorrect.show();
            }
        });
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //txt3.setText("Try again");
                snackbarWrong.show();

            }
        });
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent =new Intent(FullscreenActivity.this, Activity2.class);
                startActivity(intent);
            }
        });

    } // end of onCreate
}// end of activity

Answer 1

尝试在private final Object firstfragment；下面添加一个无参数默认构造函数，如错误所述：

 public FullscreenActivity(){}

因此，您的整个代码应该是：

package com.example.quiz;

import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import com.google.android.material.snackbar.Snackbar;
import java.util.Objects;

public class FullscreenActivity extends AppCompatActivity {
    Button btn1;
    Button btn2;
    Button btn3;
    Button btn4;
    TextView txt1;
    TextView txt2;
    TextView txt3;
    View mainView;
    Snackbar snackbarCorrect;
    Snackbar snackbarWrong;
    private final Object FirstFragment;
    
// Only change required
    public FullscreenActivity(){}

    public FullscreenActivity(Object firstFragment) {
        FirstFragment = firstFragment;
    }


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Objects.requireNonNull(getSupportActionBar()).hide();
        setContentView(R.layout.activity_fullscreen);

        if (savedInstanceState == null){
            getSupportFragmentManager().beginTransaction().
                    setReorderingAllowed(true).
                    add(R.id.Fragment, (Fragment) FirstFragment, null).
                    commit();
        }
        btn1 = findViewById(R.id.choice1);
        btn2 = findViewById(R.id.choice2);
        btn3 = findViewById(R.id.choice3);
        btn4 = findViewById(R.id.choice4);
        mainView = findViewById(R.id.matchmaker);
        txt1 = findViewById(R.id.textView1);
        txt2 = findViewById(R.id.TextView2);
        txt3 = findViewById(R.id.TextView3);
        //READ ABOUT EVENT HANDLERS , Listeners
        snackbarCorrect = Snackbar.make(mainView, "Well done!", 1000);
        snackbarWrong = Snackbar.make(mainView, "Try again!", 1000);
        mainView.setOnClickListener(v -> mainView.setBackgroundColor(Color.BLUE));

        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //txt1.setText("Try again");
                snackbarWrong.show();
            }
        });

        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //txt2.setText("Well done that\nis correct");
                snackbarCorrect.show();
            }
        });
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //txt3.setText("Try again");
                snackbarWrong.show();

            }
        });
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent =new Intent(FullscreenActivity.this, Activity2.class);
                startActivity(intent);
            }
        });

    } // end of onCreate
}// end of activity