title: How can I use the square root of a number that the user enters in an input box, instead of the number itself?
body: <p>I'm trying to make an Android app, and the feature that I'm working on right now is calculating the square root of a number entered by the user.</p>
  
  <p>How can I take a number that the user enters in a text box, and use the square root of that number in the <code>doCalc</code> part of my program? I'm limiting the number to be an integer between 1 and 20. For example, if the user enters <code>2</code> in the input box, I want to use <code>1.41</code> in the <code>doCalc</code> method. </p>
  
  <p>Here is my .java code:</p>
  
  <pre><code>package learn.text;
  
  import android.app.Activity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.TextView;
  
  public class LearntextActivity extends Activity {
      TextView text;
      EditText input;
      TextView text2;
      EditText input2;
      TextView text3;
      EditText input3;
      Button calc;
      TextView output;
  
      /** Called when the activity is first created. */
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.main);
          text = (TextView) findViewById(R.id.text);
          text.setText("Enter the design GPM for Chiller");
          input = (EditText) findViewById(R.id.input);
          text2 = (TextView) findViewById(R.id.text2);
          text2.setText("Enter the Square root of the actual pressure drop across the coil");
          input2 = (EditText) findViewById(R.id.input2);
          text3 = (TextView) findViewById(R.id.text3);
          text3.setText("Enter the design pressure drop of coil");
          input3 = (EditText) findViewById(R.id.input3);
          calc = (Button) findViewById(R.id.calc);
          output = (TextView) findViewById(R.id.output);
      } 
      public void doCalc (View view)  {
          double mInput = Double.parseDouble(input.getText().toString());
          double mInput2 = Double.parseDouble(input2.getText().toString());
          double mInput3 = Double.parseDouble(input3.getText().toString());
  
          double mOutput = (mInput*mInput2)/(mInput3);
          output.setText("GPM is" + mOutput);
      }    
  }
  </code></pre>
  
  <p>Here is the .xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:orientation="vertical" &gt;
  
      &lt;TextView
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:text="@string/hello" /&gt;
      &lt;TextView android:layout_height="wrap_content" android:text="" android:layout_width="wrap_content" android:id="@+id/text"&gt;&lt;/TextView&gt;
      &lt;EditText android:layout_height="wrap_content" android:text="" android:layout_width="match_parent" android:id="@+id/input"&gt;&lt;/EditText&gt;
      &lt;TextView android:layout_height="wrap_content" android:text="" android:layout_width="wrap_content" android:id="@+id/text2"&gt;&lt;/TextView&gt;
      &lt;EditText android:layout_height="wrap_content" android:text="" android:layout_width="match_parent" android:id="@+id/input2"&gt;&lt;/EditText&gt;
      &lt;TextView android:layout_height="wrap_content" android:text="" android:layout_width="wrap_content" android:id="@+id/text3"&gt;&lt;/TextView&gt;
      &lt;EditText android:layout_height="wrap_content" android:text="" android:layout_width="match_parent" android:id="@+id/input3"&gt;&lt;/EditText&gt;
  
      &lt;Button android:layout_height="wrap_content" android:text="Get GPM" android:layout_width="wrap_content" android:id="@+id/calc" android:password="false" android:onClick="doCalc"&gt;&lt;/Button&gt;
      &lt;TextView android:layout_height="wrap_content" android:text="" android:layout_width="wrap_content" android:id="@+id/output"&gt;&lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Here is the manifest file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="learn.text"
      android:versionCode="1"
      android:versionName="1.0" &gt;
  
      &lt;uses-sdk android:minSdkVersion="10" /&gt;
  
      &lt;application
          android:icon="@drawable/ic_launcher" android:label="string/app_name"&gt; 
          android:label="@string/app_name" &gt;
          &lt;activity
              android:name=".LearntextActivity"
              android:label="@string/app_name" &gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
  
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;
      &lt;/application&gt;
  &lt;/manifest&gt;
  </code></pre>