Decision Making in Java<\/h3>\n
Decision making in Java is done with the help of selection statements or selection constructs. The selection construct means the flow of execution of statement(s) depends upon a test-condition.<\/p>\n
If a condition is fulfilled, a course-of-action (a set of statements) is followed otherwise, another course-of-action (a different set of statements) is followed. This selection construct is also called the decision construct because it helps in decision-making about which set-of-statements are to be executed.<\/p>\n
The following figure explains the selection or decision construct:<\/em><\/p>\n Java provides two types of decision-making statements:<\/p>\n The if<\/strong> statement can be further divided into many categories that we will cover in this article. We will also discuss the jump statements in Java, which are break<\/strong> and continue<\/strong>. Let\u2019s start talking about each decision statement with syntax and examples.<\/p>\n An if<\/strong> statement checks a particular condition; if the condition evaluates to true, it will execute a statement or a set of statements. Otherwise, if the condition is false, it will ignore that statement or set of statements. The test expression of if must be of boolean type.<\/p>\n The general form or syntax of the if statement is:<\/strong><\/p>\n Here, the statement can be a single statement, a compound statement or even an empty statement.<\/p>\n If we do not provide the curly braces \u2018{\u2018 and }\u2019 after the if statement<\/strong> then by default it will consider the immediate single statement after the if statement.<\/p>\n For example,<\/strong><\/p>\n In the above code, if the condition is true then the if statement considers the only statement1 to be inside the if-block.<\/p>\n The following figure shows the if construct of Java.<\/em><\/p>\n Code to illustrate the if statement:<\/strong><\/p>\n Output:<\/strong><\/p>\n Caution!!<\/strong> Do not put a semicolon after the test condition in the if statement. If you do so, the if statement will end there. The block of statements following the if statement will no longer be the part of if in such cases.<\/em><\/p>\n The if statement only allows us to execute a set of statements if a condition or expression is true. What if there is another course of action to be followed if the expression evaluates to false? So, there comes another form of if<\/strong> that allows for this kind of either-or condition by providing an else<\/strong> clause.<\/p>\n It is called an if-else statement in which we can use the else statement with an if statement so that we can execute a block of code when the test condition is false.<\/p>\n The general form or syntax of the if-else<\/em> statement is:<\/strong><\/p>\n Note: Remember, in an if-else statement, only the code associated with the if<\/strong> or the code associated with else<\/strong> executes, both can never execute together.<\/em><\/p>\n The following figure shows the if-else construct of Java.<\/em><\/p>\n Code to illustrate the if-else statement:<\/strong><\/p>\n Output:<\/strong><\/p>\n A nested if is an if statement that has another if in its if\u2019s body or in its else\u2019s body. As Java allows nested if statements, we can place an if or else-if statement inside another if statement.<\/p>\n The general form or syntax of the Nested if statement can either be in 3 forms:<\/strong><\/p>\n The following figure shows the Nested if construct of Java.<\/em><\/p>\n Code to illustrate the Nested if statement:<\/strong><\/p>\n Output:<\/strong><\/p>\n The if-else-if ladder is a very common programming constructs in Java, which is also called the if-else-if staircase because of its appearance. We can use many if-else-if statements in our program.<\/p>\n The general form or syntax of the if-else-if ladder statement is:<\/strong><\/p>\n The following figure shows the if-else-if ladder of Java.<\/em><\/p>\n Output:<\/strong><\/p>\n A switch<\/strong> statement is a multiple-branch statement in Java. The switch statement successively checks the value of an expression with a list of integer or character constants.<\/p>\n The data type of expression in a switch must be byte, char, short or int. When a match is found, the statements associated with that constant are executed.<\/p>\n The general form or syntax of the switch statement is:<\/strong><\/p>\n The switch statement evaluates the expression and matches the values against the constant values which are specified in the case<\/strong> statements.<\/p>\n When a match is found, the statement associated with that case is executed until it encounters a break<\/strong> statement or else the switch statement ends. When no match is found, the default<\/strong> statement gets executed.<\/p>\n In the absence of break<\/strong>, the control flow moves to the next case below the matching case and this is called fall through<\/strong>.<\/p>\n![\"Selection](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/Selection-Construct-in-Java.png\")
<\/a><\/p>\nTypes of Decision Making Statements in Java<\/h3>\n
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1. The if statement in Java<\/h4>\n
if( test-condition)\n{\n \/\/statement(s);\n}<\/pre>\nif( test-condition)\n \/\/statement1;\n \/\/statement2;<\/pre>\n
![\"If](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/Working-of-If-in-Java.png\")
<\/a><\/p>\npackage com.TechVidvan.DecisionMakingDemo;\n\/\/Java program to illustrate If statement\npublic class IfStatementDemo\n{\n public static void main(String args[])\n {\n int i = 5;\n\n if (i % 2 == 0)\n System.out.println(\"5 is divisible by 2\");\n \/\/ This statement will be executed\n \/\/ as if considers one statement by default\n System.out.println(\"I am Not in if block\");\n }\n}<\/pre>\n2. The if-else statement in Java<\/h4>\n
if( test-condition)\n{\n \/\/statement(s);\n}\nelse\n{\n \/\/statement(s);\n}<\/pre>\n![\"if-else](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/If-else-Statement-in-Java.png\")
<\/a><\/p>\npackage com.TechVidvan.DecisionMakingDemo;\n\/\/Java program to illustrate If-else statement\npublic class IfElseStatementDemo\n{\n public static void main(String args[])\n {\n int i = 5;\n\n if (i % 2 == 0)\n System.out.println(\"5 is divisible by 2\");\n\n else\n System.out.println(\"5 is not divisible by 2\");\n }\n}<\/pre>\n3. The Nested-Ifs statements in Java<\/h4>\n
if(expression1) {\n :\n if(expression2)\n statement1;\n else\n statement2 ;\n :\n}\nelse\n body of else;<\/pre>\nif(expression1) {\n body of if ;\n else { :\n if(expression2)\n statement1;\n else\n statement2;\n }<\/pre>\nif(expression1) {\n :\n if(expression2)\n statement1;\n else\n statement2 ;\n :\n}\nelse {\n if(expression3)\n statement3;\n else\n statement4;\n}<\/pre>\n![\"Nested](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/Nested-if-in-Java.png\")
<\/a><\/p>\npackage com.TechVidvan.DecisionMakingDemo;\n\/\/Java program to illustrate Nested If statement\npublic class NestedIfDemo\n{\n public static void main(String args[])\n {\n int age = 18, weight = 50 ;\n\n if (age >= 18)\n {\n System.out.println(\"You are eligible to vote\");\n if (weight >= 50)\n System.out.println(\"You are eligible to vote and donate blood\");\n else\n System.out.println(\"you are not eligible to donate blood\") ;\n }\nelse\n System.out.println(\"you are not eligible for both!!\") ;\n }\n}<\/pre>\n
\nYou are eligible to vote and donate blood<\/div>\n4. The if-else-if Ladder Statement of Java<\/h4>\n
if( expression1)\n statement1 ;\nelse if(expression2)\n statement2;\n .\n .\nelse\n statement3;<\/pre>\n
![\"If](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/If-else-if-Ladder-Statement-in-Java.png\")
<\/a>Code to illustrate the if-else-if ladder statement:<\/strong><\/p>\npackage com.TechVidvan.DecisionMakingDemo;\n\/\/Java program to illustrate Nested If statement\npublic class IfElseIfDemo\n{\n public static void main(String[] args)\n {\n int number=-13;\n\n if(number>0) {\n System.out.println(\"The number is POSITIVE\");\n }\n else if(number<0) {\n System.out.println(\"The number is NEGATIVE\");\n }\n else {\n System.out.println(\"The number is equal toZERO\");\n }\n }\n}<\/pre>\n5. The switch statement of Java<\/h4>\n
switch (expression)\n{\n case value1:\n statement1;\n break;\n\n case value2:\n statement2;\n break;\n .\n .\n case valueN:\n statementN;\n break;\n\n default:\n statementDefault;\n}<\/pre>\n
![\"Switch-Case-in-Java\"](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/Switch-Case-in-Java.png\")
<\/a><\/p>\n![\"break-statement-in-java\"](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/break-statement-in-java.png\")
<\/a><\/p>\n![\"Continue-Statement-in-Java\"](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/02\/Continue-Statement-in-Java.png\")
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