What loop statements are there in java?

Java loop statements: 1. while loop, the syntax is "while (Boolean expression) {loop body;}", the loop body is executed when the condition is true; 2. do-while loop, the syntax is "do{loop body;}while(Boolean expression);", even if the condition is not met, it will be executed at least once; 3. for loop, the syntax is "for(expression 1; expression 2; expression 3) { loop body;}"; Expression 1 is to assign a value to a variable, Expression 2 is a loop condition, and Expression 3 is to change the value of a variable.

The operating system of this tutorial: Windows 10 system, Java19.0.1 version, Dell G3 computer.

Some program segments are executed multiple times under certain conditions, which are called loop structure programs. Java provides three types of loop statements to implement loop structures, including while statements, do-while statements, and for statements. What they have in common is to determine whether to continue executing the specified program segment (loop body) based on given conditions. If the execution conditions are met, the loop body will continue to be executed, otherwise the loop body will not be executed and the loop statement will end.

1: while loop

The syntax of the while loop is as follows:

while(布尔表达式){
循环体;
}

Explanation:

The Boolean expression represents the condition for the execution of the loop body. When the condition is When true, the loop body is executed.

The loop body can be either a simple statement or a compound statement.

The execution process of the while statement is: calculate the value of the Boolean expression, if its value is true, execute the loop body; then calculate the value of the Boolean expression, if its value is true, then execute the loop body, forming Loop until the value of the Boolean expression becomes false, ending the loop.

Use while loop to calculate the sum of 1 2 3 .... 100 and display the result

2: do while loop

## The syntax of the #do-while loop is as follows:

do{
循环体;
}while(布尔表达式);

Description:

Boolean expression represents the condition for loop execution.

The loop body can be either a statement or a sequence of statements.

The execution process of the do-while statement is: execute the loop body, calculate the value of the Boolean expression, if its value is true, then execute the loop body to form a loop until the value of the Boolean expression becomes false. End the loop and execute the statement after the do-while statement.

Use do-while loop to calculate the sum of 1 2 3... 100 and display the result

3: for loop

For loop syntax structure:

for(表达式1; 表达式2; 表达式3){
循环体;
}

Description:

The function of expression 1 is to initialize the loop variable.

The function of expression 2 is to give the loop condition.

The function of expression 3 is to change the value of the loop variable.

The loop body can be one or more statements.

The execution process of the for loop is: execute expression 1, calculate expression 2, if the value of expression 2 is true, execute the loop body, execute expression 3, change the value of the loop variable, and then calculate the expression If the value of expression 2 is true, then enter the loop body to form a loop until the value of expression 2 is false, end the loop, and execute the statement after for.

Use a for loop to calculate the sum of 1 2 3 ... 100 and display the result

4: Double for loop

Print the multiplication table

5: Use of break statement

break is to end the current most recent loop

Use a while loop to calculate 1 2 3..., when the sum exceeds 100, end the loop and output the total number of numbers added

can also be used The label break lable; break directly ends the for loop

The output is:

6: Use of continue

The output is:

continue just ends the current loop and will continue to execute later

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