Cannot resolve symbol “setText” on Android Developer Tutorial webpage

Question

I'm learning about android studio and I was going through the "MyFirstApp" tutorial. However, when I try to run the app, I get the error "cannot resolve symbol "setText". Here is the code I have:

package com.example.myfirstapp;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

public class DisplayMessageActivity extends AppCompatActivity {

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

    // Get the Intent that started this activity and extract the string
    Intent intent = getIntent();
    String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

    // Capture the layout's TextView and set the string as its text
    TextView textView = findViewById(R.id.textView);
    textView.setText(message);
}

This should be typed as the same as the code on the tutorial : https://developer.android.com/training/basics/firstapp/starting-activity.html#java

This is the activity_display_message.xml file:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".DisplayMessageActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="@string/textview"
        android:textSize="14sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

I've tried to check an question that was simliar, but it seems that I've didn't do anything different: Android tutorial "Cannot resolve symbol 'setText' " Can anyone help me?

Answer 1

This code must be within onCreate():

// Get the Intent that started this activity and extract the string
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

// Capture the layout's TextView and set the string as its text
TextView textView = findViewById(R.id.textView);
textView.setText(message);

Answer 2

just make TextViewpublic and declare outside onCreate() method.

package com.example.myfirstapp;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

public class DisplayMessageActivity extends AppCompatActivity {

    public  TextView textView = findViewById(R.id.textView);

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

     // Get the Intent that started this activity and extract the string
     Intent intent = getIntent();
     String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

     // set the string as its text

     textView.setText(message);

}