java - Android Studio - Unable to instantiate activity

Question

Guys I can not find a way to run my app. Please help.

Here is the error: enter image description here

Here is my MainActivity file:

package com.example.aman.text_to_speech;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.speech.tts.TextToSpeech;
import android.widget.EditText;

import java.util.Locale;

public class MainActivity extends AppCompatActivity
{
    TextToSpeech tt;
    EditText ed = (EditText)findViewById(R.id.editText);

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

        tt = new TextToSpeech(getApplicationContext(), new TextToSpeech.OnInitListener()
        {
            public void onInit(int status)
            {
                if(status != TextToSpeech.ERROR)
                    tt.setLanguage(new Locale("hi", "IN"));
            }
        });
    }

    public void speak_my_text(View vv)
    {
        String string = ed.getText().toString();
        tt.speak(string,TextToSpeech.QUEUE_FLUSH,null,null);
    }
}

Here is my AndroidManifest file:

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Here is my app file:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "26.0.1"
    defaultConfig {
        applicationId "com.example.aman.text_to_speech"
        minSdkVersion 21
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
}

Im not getting my syntax error, im only getting the error in the logcat. So guys I really need help for my app. If anyone can give me suggestions, it will be a great help. Thanks

Answer 1

EditText ed = (EditText)findViewById(R.id.editText);

Do not call inherited methods from Activity — such as findViewById() — until after super.onCreate() .

Do not call findViewById() until the View exists, such as after setContentView() .

Change that line to be:

EditText ed;

and add this line after setContentView(R.layout.activity_main); :

ed = (EditText)findViewById(R.id.editText);

Answer 2

You are trying to access an edit text even before your activity is created and rendered the layout on which the edit text exists. Hence NullPointerException .

Move the below line in onCreate after you setContentView for the activity.

EditText ed = (EditText)findViewById(R.id.editText);

If you want ed to be available outside onCreate then only declare ed and later in onCreate you can assign it a value through findViewById .