Use colors in Android Studio

In this exercise, youll modify the Tip Calculator app presented so it uses

custom colors.

3. Open the layout for the app in the graphical editor. This layout should use the colors

from Androids built-in themes.

4. Modify the styles.xml file so the theme named AppTheme sets the windowBackground

attribute of the theme to the custom color named background.

5. View the layout in the graphical editor. The background color for the window should

now be light green.

6. Modify the styles.xml file so the theme named AppTheme sets the attributes named

textColorPrimary and textColorSecondary to the custom color named white.

7. View the layout in the graphical editor. The text color for the TextView and TextEdit

widgets should now be white, but the text color for the Buttons should still be black.

8. Modify the styles.xml file so the style named TextView.Label sets the textColor

attribute to the color named black.

9. View the layout in the Graphical Layout editor. The text color for the labels should

now be black

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:padding="10dp" >

android:id="@+id/billAmountLabel"

style="@style/TextView.Label"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="@string/bill_amount_label" />

android:id="@+id/billAmountEditText"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignBaseline="@+id/billAmountLabel"

android:layout_marginLeft="5dp"

android:layout_toRightOf="@+id/billAmountLabel"

android:ems="8"

android:inputType="numberDecimal"

android:text="@string/bill_amount" >

android:id="@+id/percentLabel"

style="@style/TextView.Label"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignLeft="@+id/billAmountLabel"

android:layout_below="@+id/billAmountLabel"

android:text="@string/tip_percent_label" />

android:id="@+id/percentTextView"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignBaseline="@+id/percentLabel"

android:layout_alignLeft="@+id/billAmountEditText"

android:padding="5dp"

android:text="@string/tip_percent" />

android:id="@+id/percentDownButton"

android:layout_width="45dp"

android:layout_height="45dp"

android:layout_alignBaseline="@+id/percentTextView"

android:layout_marginLeft="25dp"

android:layout_toRightOf="@+id/percentTextView"

android:text="@string/decrease" />

android:id="@+id/percentUpButton"

android:layout_width="45dp"

android:layout_height="45dp"

android:layout_alignBaseline="@+id/percentDownButton"

android:layout_toRightOf="@+id/percentDownButton"

android:text="@string/increase" />

android:id="@+id/tipLabel"

style="@style/TextView.Label"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignLeft="@+id/percentLabel"

android:layout_below="@+id/percentLabel"

android:text="@string/tip_amount_label" />

android:id="@+id/tipTextView"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignBaseline="@+id/tipLabel"

android:layout_alignLeft="@id/billAmountEditText"

android:padding="5dp"

android:text="@string/tip_amount" />

android:id="@+id/totalLabel"

style="@style/TextView.Label"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignLeft="@+id/tipLabel"

android:layout_below="@+id/tipLabel"

android:text="@string/total_amount_label" />

android:id="@+id/totalTextView"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignBaseline="@+id/totalLabel"

android:layout_alignLeft="@+id/tipTextView"

android:padding="5dp"

android:text="@string/total_amount" />

#141315

#736C6B

#DDE0CE

#A6D39D

#000000

#FFFFFF

Java code is

package com.murach.tipcalculator;

import java.text.NumberFormat;

import android.os.Bundle;

import android.view.KeyEvent;

import android.view.View;

import android.view.View.OnClickListener;

import android.view.inputmethod.EditorInfo;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.TextView.OnEditorActionListener;

import android.app.Activity;

import android.content.SharedPreferences;

import android.content.SharedPreferences.Editor;

public class TipCalculatorActivity extends Activity

implements OnEditorActionListener, OnClickListener {

// define variables for the widgets

private EditText billAmountEditText;

private TextView percentTextView;

private Button percentUpButton;

private Button percentDownButton;

private TextView tipTextView;

private TextView totalTextView;

// define the SharedPreferences object

private SharedPreferences savedValues;

// define instance variables that should be saved

private String billAmountString = "";

private float tipPercent = .15f;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_tip_calculator);

// get references to the widgets

billAmountEditText = (EditText) findViewById(R.id.billAmountEditText);

percentTextView = (TextView) findViewById(R.id.percentTextView);

percentUpButton = (Button) findViewById(R.id.percentUpButton);

percentDownButton = (Button) findViewById(R.id.percentDownButton);

tipTextView = (TextView) findViewById(R.id.tipTextView);

totalTextView = (TextView) findViewById(R.id.totalTextView);

// set the listeners

billAmountEditText.setOnEditorActionListener(this);

percentUpButton.setOnClickListener(this);

percentDownButton.setOnClickListener(this);

// get SharedPreferences object

savedValues = getSharedPreferences("SavedValues", MODE_PRIVATE);

}

@Override

public void onPause() {

// save the instance variables

Editor editor = savedValues.edit();

editor.putString("billAmountString", billAmountString);

editor.putFloat("tipPercent", tipPercent);

editor.commit();

super.onPause();

}

@Override

public void onResume() {

super.onResume();

// get the instance variables

billAmountString = savedValues.getString("billAmountString", "");

tipPercent = savedValues.getFloat("tipPercent", 0.15f);

// set the bill amount on its widget

billAmountEditText.setText(billAmountString);

// calculate and display

calculateAndDisplay();

}

public void calculateAndDisplay() {

// get the bill amount

billAmountString = billAmountEditText.getText().toString();

float billAmount;

if (billAmountString.equals("")) {

billAmount = 0;

}

else {

billAmount = Float.parseFloat(billAmountString);

}

// calculate tip and total

float tipAmount = billAmount * tipPercent;

float totalAmount = billAmount + tipAmount;

// display the other results with formatting

NumberFormat currency = NumberFormat.getCurrencyInstance();

tipTextView.setText(currency.format(tipAmount));

totalTextView.setText(currency.format(totalAmount));

NumberFormat percent = NumberFormat.getPercentInstance();

percentTextView.setText(percent.format(tipPercent));

}

@Override

public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {

if (actionId == EditorInfo.IME_ACTION_DONE ||

actionId == EditorInfo.IME_ACTION_UNSPECIFIED) {

calculateAndDisplay();

}

return false;

}

@Override

public void onClick(View v) {

switch (v.getId()) {

case R.id.percentDownButton:

tipPercent = tipPercent - .01f;

calculateAndDisplay();

break;

case R.id.percentUpButton:

tipPercent = tipPercent + .01f;

calculateAndDisplay();

break;

}

}

}