CODEWITHSUNDEEP
javaandroidxml
Gevo12321
Gevo12321

Reputation: 569

Getting "Unfortunately, my_app has stopped." because of NullPointerException at include in layout

So I'm learning android coding and I've come across a NullPointerException and I can't figure out why.

I know that whatever is causing the app to stop is in line 26: 

LinearLayout billLL = (LinearLayout)findViewById(R.id.billLayout);

How is it wrong? The xml file has the id I'm interested in. I would really appreciate anyone's input on this. Thanks

this is TipCalc.java

package com.example.tipcalc;

import android.os.Bundle;
import android.app.Activity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;

public class TipCalc extends Activity {

    private double bill;
    private double tipRate;
    private double tip;

    EditText billET;
    EditText tipRateET;
    EditText tipET;

    TextView billTV;
    TextView tipRateTV;
    TextView tipTV;

    LinearLayout billLL = (LinearLayout)findViewById(R.id.billLayout);
    LinearLayout tipRateLL = (LinearLayout)findViewById(R.id.tipRateLayout);
    LinearLayout tipLL = (LinearLayout)findViewById(R.id.tipLayout);

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

        bill = 0;
        tipRate = .15;
        tip = bill*tipRate;

        billET = (EditText)billLL.findViewById(R.id.editText);
        tipRateET = (EditText)tipRateLL.findViewById(R.id.editText);
        tipET = (EditText)tipLL.findViewById(R.id.editText);

        billTV = (TextView)billLL.findViewById(R.id.name);
        tipRateTV = (TextView)tipRateLL.findViewById(R.id.name);
        tipTV = (TextView)tipLL.findViewById(R.id.name);

        billTV.setText(getString(R.string.bill_total_name));
        tipRateTV.setText(getString(R.string.tip_rate));
        tipTV.setText(getString(R.string.tip_name));

        billET.addTextChangedListener(billListener);
        tipRateET.addTextChangedListener(tipRateListener);

        billET.setText(String.format("%.02f",bill));
        tipRateET.setText(String.format("%.02f",tipRate));
        tipET.setText(String.format("%.02f",tip));
    }

    private TextWatcher billListener = new TextWatcher(){

        @Override
        public void afterTextChanged(Editable s) {
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            try{
                bill = Double.parseDouble(s.toString());
            }
            catch(NumberFormatException e){
                bill = 0.0;
            }
            updateTip();
        }

    };

    private TextWatcher tipRateListener = new TextWatcher(){

        @Override
        public void afterTextChanged(Editable s) {
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            try{
                tipRate = Double.parseDouble(s.toString());
            }
            catch(NumberFormatException e){
                tipRate = 0.15;
            }
            updateTip();
        }

    };

    public void updateTip(){
        tip = bill*tipRate;
        tipET.setText(String.format("%.02f", tip));
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.tip_calc, menu);
        return true;
    }

}

this is activity_tip_calc.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/title" />

    <include
        android:id="@+id/billLayout"
        layout="@layout/line" />

    <include
        android:id="@+id/tipRateLayout"
        layout="@layout/line" />

    <include
        android:id="@+id/tipLayout"
        layout="@layout/line" />

</LinearLayout>

and this is line.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="0dip"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:inputType="number" >

        <requestFocus />
    </EditText>

</LinearLayout>

here is the log as well

07-31 18:40:30.225: E/AndroidRuntime(31866): FATAL EXCEPTION: main
07-31 18:40:30.225: E/AndroidRuntime(31866): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.tipcalc/com.example.tipcalc.TipCalc}: java.lang.NullPointerException
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.os.Handler.dispatchMessage(Handler.java:99)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.os.Looper.loop(Looper.java:137)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread.main(ActivityThread.java:5103)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at java.lang.reflect.Method.invokeNative(Native Method)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at java.lang.reflect.Method.invoke(Method.java:525)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at dalvik.system.NativeStart.main(Native Method)
07-31 18:40:30.225: E/AndroidRuntime(31866): Caused by: java.lang.NullPointerException
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.Activity.findViewById(Activity.java:1853)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at com.example.tipcalc.TipCalc.<init>(TipCalc.java:26)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at java.lang.Class.newInstanceImpl(Native Method)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at java.lang.Class.newInstance(Class.java:1130)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
07-31 18:40:30.225: E/AndroidRuntime(31866):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
07-31 18:40:30.225: E/AndroidRuntime(31866):    ... 11 more

Upvotes: 2

Views: 368

Answers (4)

codeMagic
codeMagic

Reputation: 44571

Just to add a code example to the previous 2, nicely explained answers (+1 to them for explanation), it should look something like this

LinearLayout billLL, tipRateLL, tipLL;  // declare here so they can be used anywhere in the Activity

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

    // but initialize here
    billLL = (LinearLayout)findViewById(R.id.billLayout);
    tipRateLL = (LinearLayout)findViewById(R.id.tipRateLayout);
    tipLL = (LinearLayout)findViewById(R.id.tipLayout);

Upvotes: 1

user1455310
user1455310

Reputation:

NullPointerException means the DVM is unable to find the referenced item at that location and is returning "Null".

So, You need to investigate on this. Now, Since you have the logs, It is pointing that the line where you have referenced the id of a LinearLayout is causing the issue. Now, You must look If You are having that id in your R.java file, still why you are encountering that issue. Since, You have the Linear Layout present in the activity_tip_calc layout file. So, You must have called the setContentView(viewID) before referring to the layout ID. Thanks!!

Upvotes: 0

Paul Thompson
Paul Thompson

Reputation: 3330

You're trying to findbyId before you've actually set the content view. Any finding by id should be after the line

setContentView(R.layout.activity_tip_calc);

So try placing all 3

(LinearLayout)findViewById(R.id.billLayout);

looking things after you've actually set the content view within oncreate.

The reason you get a Null is the fact that there's no layout to go searching for R.id.billLayout, the activity has no idea yet what it's layout is going to be so therefore can't work find the billLayout.

Upvotes: 2

Emil Adz
Emil Adz

Reputation: 41099

You need to run this line:

LinearLayout billLL = (LinearLayout)findViewById(R.id.billLayout);

and the two line afrer it:

 LinearLayout tipRateLL = (LinearLayout)findViewById(R.id.tipRateLayout);
LinearLayout tipLL = (LinearLayout)findViewById(R.id.tipLayout);

only after you inflated you view in this line:

setContentView(R.layout.activity_tip_calc);

and activity_tip_calc needs to have billLayout in it. While the activity doesn't have a contentView that you have specified for it you can't use the findViewById to actually look for a View in it's layout.

Upvotes: 3

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