Java If-else语句
Java If-else语句
Java
if语句它检查布尔值条件:
true 或
false 。 Java中有多种类型的if语句。
if语句它检查布尔值条件:
true 或
false 。 Java中有多种类型的if语句。
if语句
if-else 语句
if-else-if 语句
嵌套if 语句
Java if语句
Java if语句测试条件。如果条件为真，它将执行
if块。
if块。
语法:
if(condition){
//code to be executed}
示例:
//Java Program to demonstate the use of if statement.public class IfExample {
public static void main(String[] args) {
//defining an 'age' variable int age=20;
//checking the age if(age>
18){
System.out.print("Age is greater than 18");
}
}
}
输出:
Age is greater than 18 Java if-else语句
Java if-else语句也测试条件。如果条件为true，则执行
if块，否则执行
else块。
if块，否则执行
else块。
语法:
if(condition){
//code if condition is true}
else{
//code if condition is false}
示例:
//A Java Program to demonstrate the use of if-else statement.
//It is a program of odd and even number.public class IfElseExample {
public static void main(String[] args) {
//defining a variable int number=13;
//Check if the number is divisible by 2 or not if(number%2==0){
System.out.println("even number");
}
else{
System.out.println("odd number");
}
}
}
输出:
odd number
Le年示例:
如果年份可以被4和400整除，则是leap年，但不能被100整除。
public class LeapYearExample {
public static void main(String[] args) {
int year=2020;
if(((year % 4 ==0) &
&
(year % 100 !=0)) || (year % 400==0)){
System.out.println("LEAP YEAR");
}
else{
System.out.println("COMMON YEAR");
}
}
}
输出:
LEAP YEAR 使用三元运算符
我们还可以使用三元运算符(？:)来执行if ... else语句的任务。这是检查情况的简便方法。如果条件为真，则结果为？返回。但是，如果条件为假，则返回: 的结果。
示例:
public class IfElseTernaryExample {
public static void main(String[] args) {
int number=13;
//Using ternary operator String output=(number%2==0)?"even number":"odd number";
System.out.println(output);
}
}
输出:
odd number Java if-else-if阶梯语句
if-else-if阶梯语句从多个语句中执行一个条件。
语法:
if(condition1){
//code to be executed if condition1 is true}
else if(condition2){
//code to be executed if condition2 is true}
else if(condition3){
//code to be executed if condition3 is true}
...else{
//code to be executed if all the conditions are false}
示例:
//Java Program to demonstrate the use of if else-if ladder.
//It is a program of grading system for fail, D grade, C grade, B grade, A grade and A+.public class IfElseIfExample {
public static void main(String[] args) {
int marks=65;
if(marks<50){
System.out.println("fail");
}
else if(marks>=50 &&marks<60){
System.out.println("D grade");
}
else if(marks>=60 &&marks<70){
System.out.println("C grade");
}
else if(marks>=70 &&marks<80){
System.out.println("B grade");
}
else if(marks>=80 &&marks<90){
System.out.println("A grade");
}
else if(marks>=90 &&marks<100){
System.out.println("A+ grade");
}
else{
System.out.println("Invalid!");
}
}
}
输出:
C grade
检查正，负或零的程序:
public class PositiveNegativeExample {
public static void main(String[] args) {
int number=-13;
if(number>
0){
System.out.println("POSITIVE");
}
else if(number<
0){
System.out.println("NEGATIVE");
}
else{
System.out.println("ZERO");
}
}
}
输出:
NEGATIVE Java嵌套的if语句
嵌套的if语句表示另一个if块中的
if块。在此，仅当外部if块条件为true时才执行内部if块条件。
if块。在此，仅当外部if块条件为true时才执行内部if块条件。
语法:
if(condition){
//code to be executed if(condition){
//code to be executed }
}
示例:
//Java Program to demonstrate the use of Nested if Statement.public class JavaNestedIfExample {
public static void main(String[] args) {
//Creating two variables for age and weight int age=20;
int weight=80;
//applying condition on age and weight if(age>
=18){
if(weight>
50){
System.out.println("You are eligible to donate blood");
}
}
}
}
输出:
You are eligible to donate blood
示例2:
//Java Program to demonstrate the use of Nested if Statement. public class JavaNestedIfExample2 {
public static void main(String[] args) {
//Creating two variables for age and weight int age=25;
int weight=48;
//applying condition on age and weight if(age>=18){
if(weight>50){
System.out.println("You are eligible to donate blood");
}
else{
System.out.println("You are not eligible to donate blood");
}
}
else{
System.out.println("Age must be greater than 18");
}
}
}
输出:
You are not eligible to donate blood