I’m trying to create an application that figures planetary weight. In the first view the user inputs their weight and it has an enter button, in the second view is a list of radio buttons and the select button. I want it to multiply their weight by the planet’s force. To do this I needed the weight variable for both activity_main.xml and planets.xml. At first I had it in only planets, but now that it’s in main as well, the if else statements are erroring.
activity_main.xml:
<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" >
<TextView
android:id="@+id/askwtTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="17dp"
android:layout_marginTop="19dp"
android:text="@string/askwt" />
<EditText
android:id="@+id/inputwtEditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/askwtTextView"
android:layout_below="@+id/askwtTextView"
android:layout_marginTop="26dp"
android:ems="10"
android:inputType="numberDecimal" />
<Button
android:id="@+id/enterButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/inputwtEditText"
android:layout_below="@+id/inputwtEditText"
android:layout_marginTop="38dp"
android:onClick="buttonclick"
android:text="@string/enter" />
</RelativeLayout>
planets.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:id="@+id/planetTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/planet" />
<TextView
android:id="@+id/textViewform2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="" />
<RadioGroup
android:id="@+id/radioGroup1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<RadioButton
android:id="@+id/mercuryRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="@string/mercury" />
<RadioButton
android:id="@+id/venusRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/venus" />
<RadioButton
android:id="@+id/earthRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/earth" />
<RadioButton
android:id="@+id/marsRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="@string/mars" />
<RadioButton
android:id="@+id/jupiterRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/jupiter" />
<RadioButton
android:id="@+id/saturnRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/saturn" />
<RadioButton
android:id="@+id/uranusRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="@string/uranus" />
<RadioButton
android:id="@+id/neptuneRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/neptune" />
<RadioButton
android:id="@+id/plutoRadio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/pluto" />
</RadioGroup>
<Button
android:id="@+id/selectButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="buttonclick2"
android:text="@string/select" />
<TextView
android:id="@+id/textViewform2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
JAVA:
package com.deitel.planetaryweight;
import android.os.Bundle;
import android.app.Activity;
import android.widget.*;
import android.view.View;
import android.view.Menu;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.EditText;
import android.widget.TextView;
import java.text.DecimalFormat;
public class MainActivity extends Activity {
//Global variable
double weight;
private Button enter; // creates a button
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
enter = (Button) findViewById(R.id.enterButton);
//Start with first screen
setContentView(R.layout.activity_main);
}
//buttonclick for form 1
public void buttonclick(View view){
//creates an editext and assigns the resource id of the xml edittext.
EditText wtentry = (EditText)findViewById(R.id.inputwtEditText);
//Receives the input from the edittext, converts it to a double (number).
weight = Double.parseDouble(wtentry.getText().toString());
//switch views to screen 2
setContentView(R.layout.planets);
//change the value of the textview on screen 2 to the calculation value
TextView t2 = (TextView)findViewById(R.id.textViewform2);
t2.setText(Double.toString(weight));
}
//buttonclick for form 2!
public void buttonclick2(View view){
setContentView(R.layout.planets);
RadioButton mercury = (RadioButton) findViewById(R.id.mercuryRadio);
RadioButton venus = (RadioButton) findViewById(R.id.venusRadio);
RadioButton earth = (RadioButton) findViewById(R.id.earthRadio);
RadioButton mars = (RadioButton) findViewById(R.id.marsRadio);
RadioButton jupiter = (RadioButton) findViewById(R.id.jupiterRadio);
RadioButton saturn = (RadioButton) findViewById(R.id.saturnRadio);
RadioButton uranus = (RadioButton) findViewById(R.id.uranusRadio);
RadioButton neptune = (RadioButton) findViewById(R.id.neptuneRadio);
RadioButton pluto = (RadioButton) findViewById(R.id.plutoRadio);
//Makes a variable for the entered amount
Double mercurypf;
Double venuspf;
Double earthpf;
Double marspf;
Double jupiterpf;
Double saturnpf;
Double uranuspf;
Double neptunepf;
Double plutopf;
Double weight;
// constants
final double mercuryforce = 0.38;
final double venusforce = 0.91;
final double earthforce = 1.00;
final double marsforce = 0.38;
final double jupiterforce = 2.34;
final double saturnforce = 1.06;
final double uranusforce = .92;
final double neptuneforce = 1.19;
final double plutoforce = 0.06;
// Code used to determine which planet RadioButton is checked:
if(mercury.isChecked())
{
mercurypf = mercuryforce * weight;
}
else
{
mercurypf = 0.00;
}
if(venus.isChecked())
{
venuspf = venusforce * weight;
}
else
{
venuspf = 0.00;
}
if(earth.isChecked())
{
earthpf = earthforce * weight;
}
else
{
earthpf = 0.00;
}
if(mars.isChecked())
{
marspf = marsforce * weight;
}
else
{
marspf = 0.00;
}
if(jupiter.isChecked())
{
jupiterpf =jupiterforce * weight;
}
else
{
jupiterpf = 0.00;
}
if(saturn.isChecked())
{
saturnpf = saturnforce * weight;
}
else
{
saturnpf = 0.00;
}
if(uranus.isChecked())
{
uranuspf = uranusforce * weight;
}
else
{
uranuspf = 0.00;
}
if(neptune.isChecked())
{
neptunepf = neptuneforce * weight;
}
else
{
neptunepf = 0.00;
}
if(pluto.isChecked())
{
plutopf = plutoforce * weight;
}
else
{
plutopf = 0.00;
}
}
}
In addition to the rest, there’s some structural and design issues you need to resolve. Take a look at the docs for information on passing information back and forth to and from Activities.
setContentView()shouldn’t be called more than once in an Activity unless you have a good reason to.