java - How to initialize an ArrayList

MainActivity.java 
 package com.cfsuman.me.javaexamples;  import android.graphics.Color; import android.graphics.drawable.ColorDrawable; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Window; import android.widget.RelativeLayout; import android.widget.TextView;  import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.Iterator;   public class MainActivity extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         requestWindowFeature(Window.FEATURE_ACTION_BAR);         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          // Set background color for action kafetaria         getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.RED));          // Get widget reference from XML layout         RelativeLayout rl = (RelativeLayout) findViewById(R.id.rl);         TextView tv = (TextView) findViewById(R.id.tv);          // Empty the TextView         tv.setText("");          // Initialize a new ArrayList         List<String> colors = new ArrayList<>();         // Add some elements to ArrayList         colors.add("Red");         colors.add("Green");         colors.add("Blue");          // Iterate through colors ArrayList         tv.setText(tv.getText() + "Colors : ");         for(int i=0;i<colors.size();i++){             tv.setText(tv.getText() + colors.get(i) + ", ");         }          // Initialize an Integer data type ArrayList         List<Integer> numbers = new ArrayList<>();         // Add some elements to ArrayList         numbers.add(1);         numbers.add(2);         numbers.add(3);          // Iterate through numbers ArrayList         tv.setText(tv.getText() + "\nNumbers : ");         for(int i=0;i<numbers.size();i++){             tv.setText(tv.getText() + "" + numbers.get(i) + ", ");         }          // Initialize an Boolean data type ArrayList         List<Boolean> status = new ArrayList<>();         // Add some elements to ArrayList         status.add(true);         status.add(false);         status.add(Boolean.TRUE);         status.add(Boolean.FALSE);          // Iterate through status ArrayList         tv.setText(tv.getText() + "\nStatus : ");         for(int i=0;i<status.size();i++){             tv.setText(tv.getText() + "" + status.get(i) + ", ");         }          // Single line ArrayList initialization with elements         // Initialize an ArrayList with values         List<String> students = Arrays.asList("Jenny","Jones","Innee","Lizu");          // Iterate through students ArrayList         tv.setText(tv.getText() + "\nStudents : ");         Iterator it = students.iterator();         while(it.hasNext()){             tv.setText(tv.getText() + "" + it.next() + ", ");         }          // Initialize an Integer data type ArrayList with values         List<Integer> marks = Arrays.asList(66,85,99);          // Iterate through marks ArrayList         tv.setText(tv.getText() + "\nMarks : ");         for(int i=0;i<marks.size();i++){             tv.setText(tv.getText() + "" + marks.get(i) + ", ");         }          // Initialize an ArrayList when you have only one element         List<String> singleColor = Collections.singletonList("Yellow");          // Iterate through single color ArrayList         tv.setText(tv.getText() + "\nSingle Color : ");         for(int i=0;i<singleColor.size();i++){             tv.setText(tv.getText() + "" + singleColor.get(i) + ",");         }     } }
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