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Android Studio Page Spitter

Time：09-09

Regards to all.

I am a beginner in Android Studio. I'm trying to make a simple application that converts long text into multiple pages. I found an old example of the "PageSplitter" project, but the new version of Android Studio reported a lot of errors. I managed to debug it but when I start the project in the emulator it starts to open and then a message appears that the application has been terminated. Can anyone help me find the error. Thanks in advance. Here is the code:

AndroidManifest.xml

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

<application
    android:allowBackup="true"
    android:dataExtractionRules="@xml/data_extraction_rules"
    android:fullBackupContent="@xml/backup_rules"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/Theme.Pagesplitterapp"
    tools:targetApi="31">
    <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>

MainActivity.java

package ru.appheads.pagesplitterapp;

import android.os.Bundle;
import android.text.TextPaint;
import android.view.ViewTreeObserver;

import androidx.fragment.app.FragmentActivity;
import androidx.viewpager.widget.ViewPager;


public class MainActivity extends FragmentActivity {
private ViewPager pagesView;

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

    setContentView(R.layout.activity_main);
    pagesView = (ViewPager) findViewById(R.id.pages);

    // to get ViewPager width and height we have to wait global layout
    pagesView.getViewTreeObserver().addOnGlobalLayoutListener(new
ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            PageSplitter pageSplitter = new PageSplitter(pagesView.getWidth(),
pagesView.getHeight(), 1, 0);

            TextPaint textPaint = new TextPaint();
            textPaint.setTextSize(getResources().getDimension(R.dimen.text_size));
            for (int i = 0; i < 1000; i  ) {
                pageSplitter.append("Hello, ", textPaint);
                textPaint.setFakeBoldText(true);
                pageSplitter.append("world", textPaint);
                textPaint.setFakeBoldText(false);
                pageSplitter.append("! ", textPaint);
                if ((i   1) % 100 == 0) {
                    pageSplitter.append("\n", textPaint);
                }
            }

            pagesView.setAdapter(new TextPagerAdapter(getSupportFragmentManager(),
pageSplitter.getPages()));
            pagesView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
        }
    });

 }
 }

PageFragment.java

package ru.appheads.pagesplitterapp;

import android.os.Bundle;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.fragment.app.Fragment;

public class PageFragment extends Fragment {
private final static String PAGE_TEXT = "PAGE_TEXT";

public static PageFragment newInstance(CharSequence pageText) {
    PageFragment frag = new PageFragment();
    Bundle args = new Bundle();
    args.putCharSequence(PAGE_TEXT, pageText);
    frag.setArguments(args);
    return frag;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle
savedInstanceState) {
    CharSequence text = getArguments().getCharSequence(PAGE_TEXT);
    TextView pageView = (TextView) inflater.inflate(R.layout.page, container, false);
    pageView.setTextSize(TypedValue.COMPLEX_UNIT_PX,
getResources().getDimension(R.dimen.text_size));
    pageView.setText(text);
    return pageView;
}
}

PageSpitter.java

package ru.appheads.pagesplitterapp;

import android.graphics.Typeface;
import android.text.SpannableString;
import android.text.SpannableStringBuilder;
import android.text.TextPaint;
import android.text.style.StyleSpan;

import java.util.ArrayList;
import java.util.List;

public class PageSplitter {
private final int pageWidth;
private final int pageHeight;
private final float lineSpacingMultiplier;
private final int lineSpacingExtra;
private final List<CharSequence> pages = new ArrayList<CharSequence>();
private SpannableStringBuilder currentLine = new SpannableStringBuilder();
private SpannableStringBuilder currentPage = new SpannableStringBuilder();
private int currentLineHeight;
private int pageContentHeight;
private int currentLineWidth;
private int textLineHeight;

public PageSplitter(int pageWidth, int pageHeight, float lineSpacingMultiplier, int
lineSpacingExtra) {
    this.pageWidth = pageWidth;
    this.pageHeight = pageHeight;
    this.lineSpacingMultiplier = lineSpacingMultiplier;
    this.lineSpacingExtra = lineSpacingExtra;
}

public void append(String text, TextPaint textPaint) {
    textLineHeight = (int) Math.ceil(textPaint.getFontMetrics(null) * lineSpacingMultiplier  
lineSpacingExtra);
    String[] paragraphs = text.split("\n", -1);
    int i;
    for (i = 0; i < paragraphs.length - 1; i  ) {
        appendText(paragraphs[i], textPaint);
        appendNewLine();
    }
    appendText(paragraphs[i], textPaint);
}

private void appendText(String text, TextPaint textPaint) {
    String[] words = text.split(" ", -1);
    int i;
    for (i = 0; i < words.length - 1; i  ) {
        appendWord(words[i]   " ", textPaint);
    }
    appendWord(words[i], textPaint);
}

private void appendNewLine() {
    currentLine.append("\n");
    checkForPageEnd();
    appendLineToPage(textLineHeight);
}

private void checkForPageEnd() {
    if (pageContentHeight   currentLineHeight > pageHeight) {
        pages.add(currentPage);
        currentPage = new SpannableStringBuilder();
        pageContentHeight = 0;
    }
}

private void appendWord(String appendedText, TextPaint textPaint) {
    int textWidth = (int) Math.ceil(textPaint.measureText(appendedText));
    if (currentLineWidth   textWidth >= pageWidth) {
        checkForPageEnd();
        appendLineToPage(textLineHeight);
    }
    appendTextToLine(appendedText, textPaint, textWidth);
}

private void appendLineToPage(int textLineHeight) {
    currentPage.append(currentLine);
    pageContentHeight  = currentLineHeight;

    currentLine = new SpannableStringBuilder();
    currentLineHeight = textLineHeight;
    currentLineWidth = 0;
}

private void appendTextToLine(String appendedText, TextPaint textPaint, int textWidth) {
    currentLineHeight = Math.max(currentLineHeight, textLineHeight);
    currentLine.append(renderToSpannable(appendedText, textPaint));
    currentLineWidth  = textWidth;
}

public List<CharSequence> getPages() {
    List<CharSequence> copyPages = new ArrayList<CharSequence>(pages);
    SpannableStringBuilder lastPage = new SpannableStringBuilder(currentPage);
    if (pageContentHeight   currentLineHeight > pageHeight) {
        copyPages.add(lastPage);
        lastPage = new SpannableStringBuilder();
    }
    lastPage.append(currentLine);
    copyPages.add(lastPage);
    return copyPages;
}

private SpannableString renderToSpannable(String text, TextPaint textPaint) {
    SpannableString spannable = new SpannableString(text);

    if (textPaint.isFakeBoldText()) {
        spannable.setSpan(new StyleSpan(Typeface.BOLD), 0, spannable.length(), 0);
    }
    return spannable;
 }
 }

TextAdapter.java

package ru.appheads.pagesplitterapp;

import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;

import java.util.List;

public class TextPagerAdapter extends FragmentPagerAdapter {
private final List<CharSequence> pageTexts;

public TextPagerAdapter(FragmentManager fm, List<CharSequence> pageTexts) {
    super(fm);
    this.pageTexts = pageTexts;
}

@Override
public Fragment getItem(int i) {
    return PageFragment.newInstance(pageTexts.get(i));
}

@Override
public int getCount() {
    return pageTexts.size();
}
}

activity_main.xml

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="ru.appheads.pagesplitterapp.MainActivity">

<androidx.viewpager2.widget.ViewPager2 xmlns:android="http://schemas.android.com/apk/res
/android"
    android:id="@ id/pages"
    android:overScrollMode="never"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
</androidx.viewpager2.widget.ViewPager2>
</RelativeLayout>

Page.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:lineSpacingMultiplier="1"
android:lineSpacingExtra="0sp">
</TextView>

styles.xml

<resources>
<style name="AppTheme" parent="android:Theme.Holo.Light.DarkActionBar">
</style>
</resources>

build.gradle.app

plugins {
id 'com.android.application'
}

android {
compileSdk 32

defaultConfig {
    applicationId "ru.appheads.pagesplitterapp"
    minSdk 21
    targetSdk 32
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-
rules.pro'
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}
}

dependencies {

implementation 'androidx.appcompat:appcompat:1.5.0'
implementation 'com.google.android.material:material:1.6.1'
implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
implementation 'androidx.viewpager2:viewpager2:1.0.0'
//implementation 'androidx.fragment:fragment-ktx:1.2.0-beta02'
testImplementation 'junit:junit:4.13.2'
androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

}

CodePudding user response：

This is a 1/4 of logcat content.

This is second logcat - after clear logcat.

2022-09-08 23:03:25.664 6760-6760/? I/pagesplitterap: Late-enabling
-Xcheck:jni
2022-09-08 23:03:25.731 6760-6760/? I/pagesplitterap: Unquickening 12
vdex files!
2022-09-08 23:03:25.737 6760-6760/? W/pagesplitterap: Unexpected CPU 
variant for X86 using defaults: x86
2022-09-08 23:03:26.651 6760-6760/ru.appheads.pagesplitterapp 
D/NetworkSecurityConfig: No Network Security Config specified, using 
platform default
2022-09-08 23:03:26.651 6760-6760/ru.appheads.pagesplitterapp
D/NetworkSecurityConfig: No Network Security Config specified, using 
platform default
2022-09-08 23:03:26.739 6760-6783/ru.appheads.pagesplitterapp
D/libEGL: 
loaded /vendor/lib/egl/libEGL_emulation.so
2022-09-08 23:03:26.743 6760-6783/ru.appheads.pagesplitterapp 
D/libEGL: 
loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
2022-09-08 23:03:26.753 6760-6783/ru.appheads.pagesplitterapp 
D/libEGL: 
loaded /vendor/lib/egl/libGLESv2_emulation.so
2022-09-08 23:03:27.182 6760-6760/ru.appheads.pagesplitterapp 
D/AndroidRuntime: Shutting down VM


--------- beginning of crash
2022-09-08 23:03:27.184 6760-6760/ru.appheads.pagesplitterapp
 E/AndroidRuntime: FATAL EXCEPTION: main
Process: ru.appheads.pagesplitterapp, PID: 6760
java.lang.RuntimeException: Unable to start activity
ComponentInfo   {ru.appheads.pagesplitterapp
/ru.appheads.pagesplitterapp.MainActivity}:
java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 
cannot be cast to androidx.viewpager.widget.ViewPager
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.ClassCastException:
 androidx.viewpager2.widget.ViewPager2 cannot be cast to
 androidx.viewpager.widget.ViewPager
    at ru.appheads.pagesplitterapp.MainActivity.onCreate 
 (MainActivity.java:19)
    at android.app.Activity.performCreate(Activity.java:7994)
    at android.app.Activity.performCreate(Activity.java:7978)
    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) 
2022-09-08 23:03:27.217 6760-6760/ru.appheads.pagesplitterapp
I/Process: Sending signal. PID: 6760 SIG: 9

CodePudding user response：

you are using Viewpager2 in xml and imported and declared Viewpager in MainActivity, that's why you are getting ClassCastException. Both xml and activity viewPager type should be same

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