我以前做过一个简单的应用程序，只是使用seekbar和SharedReferences设置字体大小。然而，当我尝试使用片段时，它显示了这个错误。

2021-07-08 19:18:54.164 12897-12897/com.example.testtt E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.testtt, PID: 12897
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SeekBar.setProgress(int)' on a null object reference
        at com.example.testtt.SizeFontFragment.onCreateView(SizeFontFragment.java:68)
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2963)
        at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:518)
        at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:282)
        at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:2189)
        at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:2100)
        at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:2002)
        at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:524)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

这是我的尺码。

package com.example.testtt;

import androidx.appcompat.widget.Toolbar;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.fragment.app.Fragment;

import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.TextView;

import androidx.annotation.Nullable;

import com.google.android.material.navigation.NavigationView;

import static android.content.Context.MODE_PRIVATE;

public class SizeFontFragment extends Fragment {

    int textSize = 30;
    int textSize2 = 13;
    int textSize3 = 13;

    //setbutton

    public Button buttonconfirm;

    //SharedPreferences

    SharedPreferences sharedPreferences;
    SharedPreferences.Editor editor;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_home, container, false);

        //definebutton

        buttonconfirm = v.findViewById(R.id.buttonconfirm);

        //sharedpreferences

        sharedPreferences = this.getActivity().getSharedPreferences("fontsize", MODE_PRIVATE);
        editor = sharedPreferences.edit();

        //definetextview

        TextView arabictext1 = v.findViewById(R.id.arabictextPREVIEW);
        TextView textviewsize = v.findViewById(R.id.arabictextview);
        TextView transliterationtext = v.findViewById(R.id.transliterationtextPREVIEW);
        TextView textviewsize2 = v.findViewById(R.id.transliterationtextview);
        TextView translationtext = v.findViewById(R.id.trasnlationtextPREVIEW);
        TextView textviewsize3 = v.findViewById(R.id.translationtextview);

        //seekbararabictext

        int progress = sharedPreferences.getInt("progress", 0);

        SeekBar seekbar1 = v.findViewById(R.id.seekbararab);
        seekbar1.setProgress(progress); // size 30sp

        arabictext1.setTextSize(textSize+seekbar1.getProgress());
        textviewsize.setText(seekbar1.getProgress() + "/" + seekbar1.getMax()); // 0/30

        seekbar1.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            int progressNew = 0;

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                textSize = textSize + (progress - progressNew);
                progressNew = progress;
                arabictext1.setTextSize(textSize);
                editor.putInt("progress", progress);
                editor.apply();
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

                textviewsize.setText(seekbar1.getProgress() + "/" + seekbar1.getMax()); // 0/30

            }
        });

        //seekbartransliterationtext

        int progress2 = sharedPreferences.getInt("progress2", 0);

        SeekBar seekbar2 = v.findViewById(R.id.seekbartransliteration);
        seekbar2.setProgress(progress2); // size 13sp

        transliterationtext.setTextSize(textSize2+seekbar2.getProgress());
        textviewsize2.setText(seekbar2.getProgress() + "/" + seekbar2.getMax()); // 0/13sp

        seekbar2.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            int progressNew = 0;

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

                textSize2 = textSize2 + (progress - progressNew);
                progressNew = progress;
                transliterationtext.setTextSize(textSize2);
                editor.putInt("progress2", progress);
                editor.apply();

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                textviewsize2.setText(seekbar2.getProgress() + "/" + seekbar2.getMax()); // 0/13
            }
        });

        //seekbartranslationtext

        int progress3 = sharedPreferences.getInt("progress3", 0);

        SeekBar seekbar3 = v.findViewById(R.id.seekbartranslation);
        seekbar3.setProgress(progress3); // size 13sp

        translationtext.setTextSize(textSize3+seekbar3.getProgress());
        textviewsize3.setText(seekbar3.getProgress() + "/" + seekbar3.getMax()); // 0/13

        seekbar3.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            int progressNew = 0;

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

                textSize3 = textSize3 + (progress - progressNew);
                progressNew = progress;
                translationtext.setTextSize(textSize3);
                editor.putInt("progress3", progress);
                editor.apply();

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

                textviewsize3.setText(seekbar3.getProgress() + "/" + seekbar3.getMax()); // 0/13

            }
        });

        return v;

    }
}

我试图找出错误和问题，但它似乎很好。我真的很想知道这些问题。提前谢谢