{"id":6494,"date":"2024-04-21T23:30:15","date_gmt":"2024-04-22T06:30:15","guid":{"rendered":"https:\/\/zentut.com\/java-tutorial\/java-while-loop\/"},"modified":"2024-04-21T23:31:01","modified_gmt":"2024-04-22T06:31:01","slug":"java-while-loop","status":"publish","type":"page","link":"https:\/\/www.zentut.com\/java-tutorial\/java-while-loop\/","title":{"rendered":"Java while loop"},"content":{"rendered":"\n

Summary<\/strong>: In this tutorial, you will learn how to use the Java while<\/code> loop statement to execute a block of code repeatedly as long as a specified condition is true.<\/p>\n\n\n\n

Introduction to Java while loop<\/h2>\n\n\n\n

A while<\/code> loop allows you to execute a block of code repeatedly as long as a certain condition remains true. <\/p>\n\n\n\n

Here’s the basic syntax of the while<\/code> loop:<\/p>\n\n\n

while<\/span>(condition) {\n    \/\/ Code to be executed as long as the condition is true<\/span>\n}<\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the condition<\/code> is a boolean expression that determines whether the loop should continue or terminate.<\/p>\n\n\n\n
Java evaluates the condition<\/code> before each iteration. If the condition<\/code> is true, the loop continues, otherwise, the loop exits.<\/p>\n\n\n\n
Because the while<\/code> loop statement evaluates the condition at the beginning of each iteration, the while<\/code> loop is also known as a pretest loop.<\/p>\n\n\n\n
Java while loop examples<\/h2>\n\n\n\n
Let’s take some examples of using the while<\/code> loop.<\/p>\n\n\n\n
1) Using a while loop to display numbers from 0 to 4<\/h3>\n\n\n\n
The following example uses the while<\/code> loop to print out numbers from 0 to 4:<\/p>\n\n\n
public<\/span> class<\/span> App<\/span> <\/span>{\n    public<\/span> static<\/span> void<\/span> main<\/span>(String[] args)<\/span> <\/span>{\n        int<\/span> count = 0<\/span>;\n        while<\/span>(count < 5<\/span>){\n            System.out.println(count);\n            count++;\n        }\n    }\n}<\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
0<\/span>\n1<\/span>\n2<\/span>\n3<\/span>\n4<\/span><\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, declare a variable<\/a> count<\/code> and initialize its value to zero.<\/p>\n\n\n\n
Second, use the while<\/code> loop to print the value of the count<\/code> variable as long as the count<\/code> is less than 5. <\/p>\n\n\n\n
Inside the loop, we increment the count<\/code> variable by one in each iteration using count++<\/code>. The loop will continue until the condition count < 5<\/code> becomes false<\/code>. Once the count is 5, the loop exits. <\/p>\n\n\n\n
Notice that if you forget to increase the count<\/code> inside the loop, the condition count < 5<\/code> is always true. As a result, the loop will run forever. In this case, you’ll have an indefinite loop<\/strong>.<\/p>\n\n\n\n
2) Using a while loop to calculate the sum of numbers<\/h3>\n\n\n\n
The following program uses a while<\/code> loop to calculate the sum of all integers from 1 to 100:<\/p>\n\n\n
public<\/span> class<\/span> App<\/span> <\/span>{\n    public<\/span> static<\/span> void<\/span> main<\/span>(String[] args)<\/span> <\/span>{\n        int<\/span> count = 1<\/span>, total = 0<\/span>;\n\n        while<\/span>(count <= 100<\/span>){\n            total += count;\n            count++;\n        }\n        \n        System.out.println(total);\n    }\n}<\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
5050<\/span><\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
    \n
  • First, declare the count<\/code> variable and initialize its value to 1. Also, declare the total<\/code> variable with the initial value of 0.<\/li>\n\n\n\n
  • Second, use a while<\/code> loop that adds up the count<\/code> to the total<\/code> as long as the count<\/code> is less than or equal to 100. <\/li>\n\n\n\n
  • Third, display the total<\/code>.<\/li>\n<\/ul>\n\n\n\n
    Notice that this example is for demonstration purposes. If you know Math, you can calculate the total of all integers from 1 to n using the formula: n * (n + 1) \/ 2<\/code>. <\/p>\n\n\n\n
    Here’s the program:<\/p>\n\n\n
    public<\/span> class<\/span> App<\/span> <\/span>{\n    public<\/span> static<\/span> void<\/span> main<\/span>(String[] args)<\/span> <\/span>{\n        int<\/span> n = 100<\/span>;\n        int<\/span> total = n * (n + 1<\/span>) \/ 2<\/span>;\n        System.out.println(total);\n    }\n}<\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
    Output:<\/p>\n\n\n
    5050<\/span><\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\n
    Summary<\/h2>\n\n\n\n
      \n
    • Use a Java while<\/code> loop to execute a block of code as long as a condition is true<\/code>.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
      In this tutorial, you will learn how to use the Java while loop statement to execute a block of code repeatedly as long as a specified condition is true.<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":2190,"menu_order":17,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-6494","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/pages\/6494","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/comments?post=6494"}],"version-history":[{"count":2,"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/pages\/6494\/revisions"}],"predecessor-version":[{"id":6496,"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/pages\/6494\/revisions\/6496"}],"up":[{"embeddable":true,"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/pages\/2190"}],"wp:attachment":[{"href":"https:\/\/www.zentut.com\/wp-json\/wp\/v2\/media?parent=6494"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}