Java If Else Statements
Java If Else Statements are conditional statements used to make decisions in a program. They allow the program to execute different blocks of code based on whether a specified condition is true or false. If the condition is true, the code within the "if" block is executed; otherwise, the code within the "else" block is executed.
5 Key excerpts on "Java If Else Statements"
eBook - ePubCoding + Math
Strengthen K–5 Math Skills With Computer Science
- Nicol R. Howard(Author)
- 2020(Publication Date)
...Example one is the simplest of the if statements, and it would only run the code between the curly braces if the condition evaluated to true; otherwise, the program would just continue to the next code below it. Example two runs the code below the if statement if the condition is true, but runs the code below the else statement if the condition is false. In example three, if condition one is true, the program will run the code under the if statement; if not, it will test for condition two, and if true, it will run the code under the else-if statement. If neither condition one nor condition two are true, it will run the code under else. Note that one and only one of the code blocks will be executed. Finally, example four adds multiple else-if statements and operates the same way as the previous example, as only one of the four code blocks will be executed. You can string together as many else-if statements as you like, each with its own condition. Learning how to use these statements, particularly in the context of programming toward a particular outcome, goes a long way in developing students’ ability to sequence and to apply logic to scenarios with predictable outcome options. Math learning is strengthened when the Boolean statements used in the conditions are based upon mathematical equations being evaluated as true or false. With this approach, the math is no longer arbitrary (as it may sometimes seem in common math exercises), but is essential to achieving a specific programming goal. Given the accepted and expected process of debugging that is part of the programming culture, learners can test their answers by running their program without any evaluation-based affect involved...
eBook - ePub- Bill Sempf, Charles Sphar, Stephen R. Davis(Authors)
- 2010(Publication Date)
- For Dummies(Publisher)
...When I say “make decisions,” I mean that the processor sends the flow of execution down one path of instructions if a condition is true or down another path if the condition is not true. Any programming language must offer this fundamental capability to control the flow of execution. The three basic types of flow control are the if statement, the loop, and the jump. (I describe one of the looping controls, the foreach, in Chapter 6 of this minibook.) Branching Out with if and switch The basis of all C# decision-making capability is the if statement (and the basis of all my decisions is the maybe): if (bool-expression) { // Control goes here if the expression is true. } // Control passes to this statement whether the expression is true or not. A pair of parentheses immediately following the keyword if contains a conditional expression of type bool. (See Chapter 2 of this minibook for a discussion of bool expressions.) Immediately following the expression is a block of code set off by a pair of braces. If the expression is true, the program executes the code within the braces; if the expression is not true, the program skips the code in the braces. (If the program executes the code in braces, it ends just after the closing brace and continues from there.) The if statement is easier to understand by looking at a concrete example: // Make sure that a is not negative: // If a is less than 0. . . if (a < 0) { //. . . then assign 0 to it so that it’s no longer negative. a = 0; } This segment of code ensures that the variable a is nonnegative — greater than or equal to 0. The if statement says, “If a is less than 0, assign 0 to a.” (In other words, turn a into a positive value.) The braces aren’t required. C# treats if(bool-expression) statement; as though it had been written if(bool-expression) {statement;}. The general consensus (and my preference) is to always use braces for better clarity...
- George Pruitt, John R. Hill(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
...If we had used logical OR, then only one of the conditional statements would need to be True. CONDITIONAL BRANCHING WITH IF-THEN-ELSE The if-then statement provides only a single branch. Many times a program requires two branches: one branch that executes if true, the other if false. This type of conditional branching can be accomplished by using the if-then-else statement. If an evaluation of a conditional statement is True, the line or block of code that follows the then statement is executed. If the evaluation is False, the line or block of code that follows the else statement is executed. The syntax for the if-then-else is: if(conditional statement) then [single statement] else [single statement]; if(conditional statement) then begin [multiple statements] end; else begin [multiple statements] end; Notice that a semicolon is not used after a statement that precedes an else statement. If one is added, it will cause a syntax error. Let's incorporate our newly found knowledge into MyStrategy-1. The following code causes our program to make a decision based on the number of days we have been in the trade. If we have been in the trade for fewer than five days, then we want to exit a long/short position on the lowest low/highest high of the past ten days. After we have been in the trade for five days or more, we will revert back to our previous exit strategy (come out of a losing position on the close after five days). if (marketPosition = 1) then begin if(barsSinceEntry(0)<5) then begin Sell("LongLoss") next bar at Lowest(low,10) stop; end else begin if(close<entryPrice) then Sell("LongLoss5Days") on this bar close; end; end; If (marketPosition = −1) then begin if(barsSinceEntry(0)<5) then begin BuyToCover("ShortLoss") next bar at Highest(high,10) stop; end else begin if(close<entryPrice) then BuyToCover("ShortLoss5Days") on this bar close; end; end; Notice how in the last else block we didn't have enough room to put the entire statement on one line...
eBook - ePubHack Audio
An Introduction to Computer Programming and Digital Signal Processing in MATLAB
- Eric Tarr(Author)
- 2018(Publication Date)
- Routledge(Publisher)
...An else statement does not have a logical expression explicitly associated with it; it is implicitly assumed all other conditional statements are FALSE. There can only be one else statement within an if statement. One or more elseif statements can be included within an if statement as an additional conditional statement. An elseif statement requires a logical expression. When the logical expression is TRUE, the commands following the elseif statement and before the next conditional statement are executed. Otherwise, if it is FALSE, the commands are not executed. There can be multiple elseif statements included within an if statement. Examples: Save and run the following m-file in MATLAB. % This script demonstrates several examples of "elseif" % and "else" statements. Observe which commands get executed, % and which do not, based on the conditional statements num = -1; % Variable for comparison if num > 0 % This is false gtz = true % Therefore this is NOT executed else % Instead, gtz = false % This is executed end num = -1; if num > 0 % This is false gtz = true elseif num < 0 % This is true ltz = true % Execute this command else % Skip all other commands, jump to end zero = true end num = 0; if num > 0 % This is false gtz = true elseif num < 0 % And this is false ltz = true else % Therefore, zero = true % Only execute this command end Example. 5.7: else and elseif conditional statements switch Statement A switch statement conditionally executes a set of statements contained in several cases. Similar to an if statement, only certain commands are executed during the program depending on the conditions of the switch statement. A switch statement evaluates whether a variable is equal to the variable in each case. If it is TRUE, the statements in that case are executed...
eBook - ePubPLC Controls with Structured Text (ST)
IEC 61131-3 and best practice ST programming
- Tom Mejer Antonsen(Author)
- 2018(Publication Date)
- Books on Demand(Publisher)
...9 Conditional Statement The following chapter consists of the central statement concepts in ST. In the general format descriptions, <Condition> and <Statement> must be replaced by variables, expressions and PLC codes 9.1 IF-THEN-ELSE An IF-THEN-ELSE statement – or a sentence – is the most used expression in ST programming. An IF statement can e.g. be used to control whether a digital sensor shows a signal (e.g. an electrical start contact, an ON/OFF switch or a level contact in a pump well). If the digital sensor shows a signal, an action is to be taken, being e.g. starting a pump or switch on a lamp. An IF statement can be used both when using analogue and digital input-signals. Further, the IF statement can be used for internal variables. The general format of the IF statement is as follows: IF <Condition> THEN <Statement> END_IF ; Where: <Statement> = Can contain one or more lines of PLC code, always ended by END_IF and semicolon. <Condition> = An expression, always being TRUE or FALSE. If the expression is true, the PLC code in <Statement> is carried out. <Condition> can e.g. be an input signal from an electrical contact and <Statement> can be an output signal to switching on or off a lamp. The statement ELSE can be added to the expression: IF <Condition> THEN <Statement> ELSE <Statement1> END_IF ; As can be seen, the ELSE part is optional and notice that the lines including <Statement> is tabulated (2 x blanks) to make the whole expression more readable. The mode of operation is as follows: If <condition> is fulfilled (TRUE), the PLC code in <Statement > will be carried out. If <condition> is not fulfilled (FALSE), the PLC code in <Statement1> is carried out. Flowchart of the IF-ELSE statement NOTICE: If <Condition> section contains colon “:”, it indicates that it is controlled if the variable assignment is carried out well, which is not the intention! Therefore, remember that the sign “=” must stand alone. It is...
