My app keeps stopping if i add a scroll view to my linear layout

Question

Hi My App Keeps crashing whenever I add a scrollView to my linear layout. I need to make a dynamic buttons according to my list and call a JASON web service. This all works perfectly before I add a scroll view. How to enable scrolling to my app or add scroll view. This app will crashing. Edit Code: i tried another method and this also crashed my app

LinearLayout layout = (LinearLayout)findViewById(R.id.linearlayout);

            tcodes = new String[] {"T32","T31","T30","T39","T40","T01","T02","T03","T04","T05","T05","T07","Q01"};
    for (int i = 0; i < tcodes.length; i++) {
        LinearLayout row = (LinearLayout)findViewById(R.id.linearlayout);
        row.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
        for(int j = 0; j<2;j++) {
            Button btnTag = new Button(this);
            btnTag.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            btnTag.setText(tcodes[i]);
            Drawable top = getResources().getDrawable(R.drawable.aikitting);
            btnTag.setCompoundDrawablesWithIntrinsicBounds(null,top,null,null);
            btnTag.setId(i);
            btnTag.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Button b = (Button)view;
                    String buttonText = b.getText().toString();

                    new UserNameToId().execute("http://172.16.206.195/aSSET_manager/ASSET_TABLE/hello_ikhsan?name=ikhsan&job=programmer");
                }
            });
            row.addView(btnTag);
        }
        layout.addView(row);

    }
    setContentView(layout);

this is my xml I dont add much in my XML except a constraint view

    <?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/scrollView"
    android:textAlignment="center"
    tools:context=".MainActivity">

        <LinearLayout
            android:layout_width="match_parent"
            android:id="@+id/linearlayout"
            android:layout_height="wrap_content"
            android:orientation="vertical" />

</ScrollView>

this is my logcat

2021-12-14 08:01:12.889 7169-7169/com.example.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.myapplication, PID: 7169
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3635)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3792)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2210)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loopOnce(Looper.java:201)
    at android.os.Looper.loop(Looper.java:288)
    at android.app.ActivityThread.main(ActivityThread.java:7839)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
 Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
    at android.view.ViewGroup.addViewInner(ViewGroup.java:5247)
    at android.view.ViewGroup.addView(ViewGroup.java:5076)
    at android.view.ViewGroup.addView(ViewGroup.java:5016)
    at android.view.ViewGroup.addView(ViewGroup.java:4988)
    at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:697)
    at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:201)
    at com.example.myapplication.MainActivity.onCreate(MainActivity.java:92)
    at android.app.Activity.performCreate(Activity.java:8051)
    at android.app.Activity.performCreate(Activity.java:8031)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1329)

Answer 1

You can not use xml recourse without setContentView, you should create a new linear layout, and you can not add to another parent if child have already.

here, your solution

    LinearLayout layout = new LinearLayout(this);
layout.setOrientation(LinearLayout.VERTICAL);
                tcodes = new String[] {"T32","T31","T30","T39","T40","T01","T02","T03","T04","T05","T05","T07","Q01"};
        for (int i = 0; i < tcodes.length; i++) {
            LinearLayout row = new LinearLayout(this); //here you are making mistake
    row.setOrientation(LinearLayout.VERTICAL);
            row.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
            for(int j = 0; j<2;j++) {
                Button btnTag = new Button(this);
                btnTag.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
                btnTag.setText(tcodes[i]);
                Drawable top = getResources().getDrawable(R.drawable.aikitting);
                btnTag.setCompoundDrawablesWithIntrinsicBounds(null,top,null,null);
                btnTag.setId(i);
                btnTag.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        Button b = (Button)view;
                        String buttonText = b.getText().toString();
                        new UserNameToId().execute("http://172.16.206.195/aSSET_manager/ASSET_TABLE/hello_ikhsan?name=ikhsan&job=programmer");
                    }
                });
                row.addView(btnTag);
            }
            layout.addView(row);
        }
        setContentView(layout);