I am trying to make a basic app in which you touch the screen and it changes the background color of the screen. However I can't set the OnTouchListener for the RelativeLayout that is containing my app essentials. The app throws an error upon building and then crashes, not sure whats going on here =/ If anyone could help that would be great =)
Java Code:
public class ColorCrazeActivity extends AppCompatActivity{
int pointCount = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
RelativeLayout myLayout = (RelativeLayout) findViewById(R.id.myRelativeLayout1);
myLayout.setOnTouchListener(
new RelativeLayout.OnTouchListener() {
public boolean onTouch(View v, MotionEvent m) {
if (m.getActionMasked() == MotionEvent.ACTION_DOWN) {
changeColor();
}
return true;
}
}
);
setContentView(myLayout);
}
public void changeColor(){
int myNum1 = (int)Math.floor(Math.random() * (255));
int myNum2 = (int)Math.floor(Math.random() * (255));
int myNum3 = (int)Math.floor(Math.random() * (255));
TextView myTextView = (TextView)findViewById(R.id.myTextView);
RelativeLayout myRelativeLayout = (RelativeLayout)findViewById(R.id.myRelativeLayout1);
myTextView.setText("RGB(" + Integer.toString(myNum1) + ", " + Integer.toString(myNum2) + ", " + Integer.toString(myNum3) + ")");
myRelativeLayout.setBackgroundColor(Color.argb(255, myNum1, myNum2, myNum3));
addPoints();
}
public void addPoints(){
pointCount += 1;
TextView myTextView1 = (TextView)findViewById(R.id.myTextView1);
myTextView1.setText(Integer.toString(pointCount));
}
}
XML Code:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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"
android:id="@+id/myRelativeLayout"
tools:context="com.toymakersdev.colorcraze.ColorCrazeActivity"
android:focusableInTouchMode="true"
android:background="#000c65">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:id="@+id/myRelativeLayout1"
android:clickable="true"
android:focusable="true"
android:focusableInTouchMode="true">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/myTextView1"
android:text="Taps: 0"
android:textSize="40dp"
android:textColor="#ffffff"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/myTextView"
android:text="Tap here"
android:textSize="50dp"
android:textAlignment="center"
android:textColor="#ffffff"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
I have a RelativeLayout nested inside of another RelativeLayout because i thought the error was because it was the root view originally. Apparently not considering its still throwing the error.
Set first the setContentView before do something with it:
For example:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.id.myLayout); //name of the layout file
}
Your activity looks now like this:
public class ColorCrazeActivity extends AppCompatActivity{
int pointCount = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.id.myLayout); //name of the layout file
RelativeLayout myLayout = (RelativeLayout) findViewById(R.id.myRelativeLayout1);
myLayout.setOnTouchListener(
new RelativeLayout.OnTouchListener() {
public boolean onTouch(View v, MotionEvent m) {
if (m.getActionMasked() == MotionEvent.ACTION_DOWN) {
changeColor();
}
return true;
}
}
);
}
public void changeColor(){
int myNum1 = (int)Math.floor(Math.random() * (255));
int myNum2 = (int)Math.floor(Math.random() * (255));
int myNum3 = (int)Math.floor(Math.random() * (255));
TextView myTextView = (TextView)findViewById(R.id.myTextView);
RelativeLayout myRelativeLayout = (RelativeLayout)findViewById(R.id.myRelativeLayout1);
myTextView.setText("RGB(" + Integer.toString(myNum1) + ", " + Integer.toString(myNum2) + ", " + Integer.toString(myNum3) + ")");
myRelativeLayout.setBackgroundColor(Color.argb(255, myNum1, myNum2, myNum3));
addPoints();
}
public void addPoints(){
pointCount += 1;
TextView myTextView1 = (TextView)findViewById(R.id.myTextView1);
myTextView1.setText(Integer.toString(pointCount));
}
Set the content view before accessing the layout
setContentView(R.layout.activity_layout);//adjust this xml layout
RelativeLayout myLayout = (RelativeLayout) findViewById(R.id.myRelativeLayout1);
myLayout.setOnTouchListener(
new RelativeLayout.OnTouchListener() {
public boolean onTouch(View v, MotionEvent m) {
if (m.getActionMasked() == MotionEvent.ACTION_DOWN) {
changeColor();
}
return true;
}
}
);
If you don't do this first, your activity has no idea where to find the view.
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