if语句

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使用Java的条件语句if,可以有选择的执行程序的某一部分.Java的if语句与其他语言中的if语句非常相似.if语句最简单的形式如下:
  1. if(condition) statement;
if(condition) statement;
此处,condition是一个boolean表达式.如果condition为真,则执行语句.如果condition为假,则跳过语句,下面是一个示例:
  1. if(10 < 11) System.out.println("10 is less than 11");
if(10 < 11) System.out.println("10 is less than 11");
因为条件表达式为真,执行println显示”10 is less than 11″
  1. if(10 < 9) System.out.println("10 is less than 9");
if(10 < 9) System.out.println("10 is less than 9");
因为条件表达式为假,所以不会显示文字
Java定义了可以在条件表达式使用的完整的关系运算符,如下表所示:
运算符
含义
<
小于
<=
小于等于
>
大于
>=
大于等于
==
等于
!=
不等于
例:
  1. public class test
  2. {
  3. // @param args
  4. public static void main(String args[])
  5. {
  6. int a,b,c;
  8. a = 2;
  9. b = 3;
  11. if(a < b) System.out.println("a is less than b");
  13. c = a - b;
  15. if(c >= 0)
  16. {
  17. System.out.println("c is non-negative");
  18. } else {
  19. System.out.println("c is negative");
  20. }
  22. }
  23. }
public class test
{
    // @param args
    public static void main(String args[])
    {
        int a,b,c;
        
        a = 2;
        b = 3;
        
        if(a < b) System.out.println("a is less than b");
        
        c = a - b;
        
        if(c >= 0)
        {
            System.out.println("c is non-negative");
        } else {
            System.out.println("c is negative");
        }
        
    }
}
输出:
  1. a is less than b
  2. c is negative
a is less than b
c is negative