I have had multiple problems with android app dev kit and I can't seem to fix it. I tried running my code and this is what shows up in logcat
Here is my main activity:
public class MainActivity extends AppCompatActivity {
EditText input = (EditText) findViewById(R.id.input);
TextView output = (TextView) findViewById(R.id.output);
ArrayList <String> charzart = new ArrayList<String>();
ArrayList <String> color = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
Button converter = (Button) findViewById(R.id.button);
int begin = 0;
int total = 16777216;
String text = input.getText().toString();
ArrayList<Integer> hexa = new ArrayList<Integer>();
//charzart array
int b = text.length();
for (int i = 1; i <= b; i++) {
charzart.add(text.substring(i - 1, i));
}
//hexa array
int a = text.length() - 1;
for (int z = 0; z < charzart.size(); z++) {
if (charzart.get(z).matches(" ")) {
a--;
}
}
int numb = total / a;
for (int x = 0; x <= 16777216; x = x + numb) {
hexa.add(x);
}
//changing into hexadecimal numbers
for (int y = 0; y < hexa.size(); y++) {
int cvalue = hexa.get(y);
int one, two, three, four, five, six;
one = cvalue / 1048570;
cvalue = cvalue - one * 1048570;
two = cvalue / 65356;
cvalue = cvalue - two * 65356;
three = cvalue / 4096;
cvalue = cvalue - three * 4096;
four = cvalue / 256;
cvalue = cvalue - four * 256;
five = cvalue / 16;
cvalue = cvalue - five * 16;
six = cvalue;
if (one != 16) {
String let = "";
String fin = "#";
switch (one) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
switch (two) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
switch (three) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
switch (four) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
switch (five) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
switch (six) {
case 0:
let = "0";
break;
case 1:
let = "1";
break;
case 2:
let = "2";
break;
case 3:
let = "3";
break;
case 4:
let = "4";
break;
case 5:
let = "5";
break;
case 6:
let = "6";
break;
case 7:
let = "7";
break;
case 8:
let = "8";
break;
case 9:
let = "9";
break;
case 10:
let = "A";
break;
case 11:
let = "B";
break;
case 12:
let = "C";
break;
case 13:
let = "D";
break;
case 14:
let = "E";
break;
case 15:
let = "F";
break;
default:
let = "x";
}
fin += let;
let = "";
color.add(fin);
fin = "#";
} else {
color.add("#FFFFFF");
}
}
//BUTTON
converter.setOnClickListener(
new View.OnClickListener() {
public void onClick(View v) {
String end = "";
for (int p = 0; p < charzart.size(); p++) {
if (charzart.get(p).equals(" ")) {
}
else{
Spannable colorSpan = new SpannableString(charzart.get(p));
int fake = Integer.parseInt(color.get(p));
colorSpan.setSpan(new ForegroundColorSpan(fake), 0, 1, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
end += colorSpan;
}
}
output.setText(end);
}
}
);
}
Here's my layout xml file:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.hitchhikingapps.rainbowz.MainActivity"
tools:showIn="@layout/activity_main">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Convert"
android:id="@+id/button"
android:layout_marginTop="124dp"
android:layout_below="@+id/input"
android:layout_centerHorizontal="true" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textMultiLine"
android:ems="10"
android:id="@+id/input"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:gravity="center_horizontal"
android:text="Insert Text here" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/output"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="78dp" />
</RelativeLayout>
And this is an error which I got it:
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.hitchhikingapps.rainbowz/com.hitchhikingapps.rainbowz.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference
at android.app.Activity.findViewById(Activity.java:2090)
at com.hitchhikingapps.rainbowz.MainActivity.<init>(MainActivity.java:22)
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Sorry for the great block of code, but I really don't understand what the problem is. Any help would be appreciate
The problem here is that you are initializing your views as global variables:
EditText input = (EditText) findViewById(R.id.input);
TextView output = (TextView) findViewById(R.id.output);
The current context of your views here is Window and not R.layout.activity_main.
If you want to use input and output as global variables, you have only to declare them:
EditText input;
TextView output;
and initialize them in onCreate() after setContentView():
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
input = (EditText) findViewById(R.id.input);
output = (TextView) findViewById(R.id.output);
}