Hur man skriver ut en ArrayList av en ArrayList i Java

Bästa svaret

import java.util.ArrayList;

import org.testng.annotations.Test;

public class arrayList {

@Test

public void arrayListTest() {

// Define array list which can hold array list objects

// of type any (String/Integer/Boolean)

ArrayList> outer = new ArrayList>();

// Define array list 1 and add data to it

ArrayList innerInt1 = new ArrayList();

innerInt1.add(100);

innerInt1.add(300);

innerInt1.add(500);

// Define array list 2 and add data to it

ArrayList innerInt2 = new ArrayList();

innerInt2.add(200);

innerInt2.add(400);

innerInt2.add(600);

// Add inner array list objects created to outer array list

// Outer array declaration says it can hold

// arraylist objects of type Integer

outer.add(innerInt1); // here innerInt1 is ArrayList Object

outer.add(innerInt2); // here innerInt2 is ArrayList Object

// Print using prinln function

System.out.println(outer);

// Pring using for loop dynamically

for(int i=0;i


  for(int j=0;j 

  System.out.println(outer.get(i).get(j)); 
  } 
  } 
  } 
 } 
 Output : 
 [[100, 300, 500], [200, 400, 600]] 
 100300500200400600 
 PASSAD: arrayListTest == ================================================ Standardtest Tester körs: 1, misslyckanden: 0, hoppar: 0 =========================================== ==== Standardsvit Totalt antal testkörningar: 1, Fel: 0, Hoppar över: 0 =================================== ================ 
 Svar 
 Vi kan visa alla element i ArrayList i Java med: 

 Med användning av för loop 
 Genom användning av förbättrad för loop 
 Genom användning av lambdauttryck 
 Genom att använda metodreferens 
 Genom att använda strömmen 

 Låt oss se i exempel: 
 import java.util.ArrayList; 
 import java.util.Arrays; 
 public class MainClass  
 { 
  public static void main(String[] arg)  
  { 
  ArrayList list = new ArrayList(Arrays.asList(1,2,3,4,5)); 
   
  // Display all the elements in ArrayList in Java using for loop? 
  System.out.println("By use of for loop"); 
  for(int i = 0; i < list.size(); i++) 
  { 
  System.out.println(list.get(i)); 
  } 
   
  // Display all the elements in ArrayList in Java using enhanced for loop? 
  System.out.println("By use of enhanced for loop"); 
  for(Integer ele : list) 
  { 
  System.out.println(ele); 
  } 
   
  // Display all the elements in ArrayList in Java using forEach loop 
  // Using lambda expression  
  System.out.println("By use of lambda expression"); 
  list.forEach(a -> System.out.println(a)); 
   
  // Display all the elements in ArrayList in Java using forEach loop 
  // Using method reference 
  System.out.println("By use of method reference"); 
  list.forEach(System.out::println); 
   
  // Display all the elements in ArrayList in Java using forEach loop with Streams 
  System.out.println("By use of stream"); 
  list.stream().forEach(ele -> System.out.println(ele)); 
   
  } 
 }

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