本文概要
Java的if语句用来测试的条件。它检查布尔条件:true或false。有各种类型的,如果在Java语句。
- if语句
- if-else语句
- 的if-else,如果阶梯
- 嵌套if语句
Java的if语句
Java的if语句测试条件。如果条件为真,它执行的if块。
句法:
if(condition){
//code to be executed
}
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的if-else语句
Java的if-else语句还测试条件。如果执行,否则else块条件为真,它执行的if块。
句法:
if(condition){
//code if condition is true
}else{
//code if condition is false
}
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
闰年示例:
一年的飞跃,如果它是由4和400整除但不是100。
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
我们也可以使用三元运算符(?:)执行if … else语句的任务。这是一种速记的方法来检查的条件。如果条件为真,结果?返回。但是,如果条件为假,结果:返回。
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的if-else语句,如果阶梯声明
如果 – 否则,如果阶梯语句执行多个语句一个条件。
句法:
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
}
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
程序检查正,负或为零:
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的嵌套if语句
if语句代表中的另一个if块,如果块的嵌套。在此,内如果块条件执行如果块的条件为真,只有当外。
句法:
if(condition){
//code to be executed
if(condition){
//code to be executed
}
}
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
实施例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
评论前必须登录!
注册