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javaandroidscreenshot

Android screenshot app in java - there is no error before run but app crashes after start

I tried to write screenshot app. I fixed all errors but app crashes after start, could you check what could be wrong? There are functions onCreate, onRequestPermissionsResult and takeScreenshot - that is key function. In which part do you thing could be error?

Thank you

I added also messages from logcat

MainActivity.java

package com.example.screenshotapp;

import android.Manifest;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.File;
import java.io.FileOutputStream;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_CODE_PERMISSION = 101;

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

        Button screenshotButton = findViewById(R.id.screenshotButton);
        screenshotButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (checkPermission()) {
                    takeScreenshot();
                } else {
                    requestPermission();
                }
            }
        });
    }

    private boolean checkPermission() {
        int permission = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        return permission == PackageManager.PERMISSION_GRANTED;
    }

    private void requestPermission() {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_PERMISSION);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_CODE_PERMISSION) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                takeScreenshot();
            } else {
                Toast.makeText(this, "Permission denied. Unable to take screenshot.", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void takeScreenshot() {
        try {
            View rootView = getWindow().getDecorView().getRootView();
            rootView.setDrawingCacheEnabled(true);
            Bitmap bitmap = Bitmap.createBitmap(rootView.getDrawingCache());
            rootView.setDrawingCacheEnabled(false);

            String fileName = "screenshot_" + new Date().getTime() + ".png";
            File screenshotFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), fileName);

            FileOutputStream outputStream = new FileOutputStream(screenshotFile);
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
            outputStream.flush();
            outputStream.close();

            Toast.makeText(this, "Screenshot saved: " + screenshotFile.getAbsolutePath(), Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "Error taking screenshot.", Toast.LENGTH_SHORT).show();
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/screenshotButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Udělat screenshot"
        android:layout_centerInParent="true" />

</RelativeLayout>

AndroidManifest.xml

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

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true">
        <activity android:name="com.example.screenshotapp.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>

This is from logcat:

Process: com.example.screenshotapp, PID: 4266 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.screenshotapp/com.example.screenshotapp.MainActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7656) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:926) at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:889) at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:772) at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:197) at com.example.screenshotapp.MainActivity.onCreate(MainActivity.java:28) at android.app.Activity.performCreate(Activity.java:8000) at android.app.Activity.performCreate(Activity.java:7984) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)  at android.os.Handler.dispatchMessage(Handler.java:106)  at android.os.Looper.loop(Looper.java:223)  at android.app.ActivityThread.main(ActivityThread.java:7656)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 

Solution

  • Your log shows clearly that your activity needs to use Theme.AppCompat as theme or any other theme that is a descendant of it, such as Theme.AppCompat.Light or Theme.AppCompat.Light.DarkActionBar. In your Manifest file, add android:theme="@style/Theme.AppCompat" attribute to the tag for your MainActivity:

    <activity android:name="com.example.screenshotapp.MainActivity"
    android:exported="true"
    android:theme="@style/Theme.AppCompat">
    
</activity>