Here is source code of the Program to Demonstrate Tip Calculator. The program is successfully compiled and run on a Windows system using Eclipse Ide. The program output is also shown below.
The following code teaches u how to change the color of a component’s text and change the background color of the component.
Main Activity
package com.example.tip_calculator; import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final EditText amt = (EditText) findViewById(R.id.bill_amt); final EditText tip = (EditText) findViewById(R.id.bill_per); final TextView result = (TextView) findViewById(R.id.res); Button calc = (Button) findViewById(R.id.button1); calc.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub double amount = Double.parseDouble(amt.toString()); double tip_per = Double.parseDouble(tip.toString()); double tip_cal = (amount * tip_per) / 100; result.setText("Result : " + Double.toString(tip_cal)); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
Actvity_Main
<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" tools:context=".MainActivity" > <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:layout_marginTop="47dp" android:background="@android:color/holo_blue_dark" android:text="Enter Your Bill amount" android:textAppearance="?android:attr/textAppearanceMedium" android:textColor="@android:color/holo_red_dark" /> <TextView android:id="@+id/res" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:layout_alignRight="@+id/button1" android:layout_marginBottom="14dp" android:text="Result : " android:textAppearance="?android:attr/textAppearanceLarge" /> <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/res" android:layout_alignParentLeft="true" android:layout_alignRight="@+id/textView2" android:layout_marginBottom="34dp" android:background="@android:color/black" android:text="Calculate" android:textColor="@android:color/white" /> <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/button1" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_marginBottom="96dp" android:background="@android:color/holo_green_dark" android:text="Enter Tip Percentage :" android:textAppearance="?android:attr/textAppearanceMedium" android:textColor="@android:color/holo_red_dark" /> <EditText android:id="@+id/bill_amt" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_below="@+id/textView1" android:layout_marginTop="41dp" android:ems="10" > <requestFocus /> </EditText> <EditText android:id="@+id/bill_per" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/button1" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_marginBottom="22dp" android:ems="10" /> </RelativeLayout>
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