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法学在 Java 中的加法和连接
Java 中的“+”运算符既可用于添加数字，也可用于连接字符串。应该考虑以下规则。
只有数字为操作数，结果将是数字。
只有字符串为操作数，结果将是连接的字符串。
如果数字和字符串都是操作数，则在字符串之前出现的数字将被视为数字。
如果数字和字符串都是操作数，则在字符串之后出现的数字将被视为字符串。
可以用括号来覆盖上述规则。
示例
创建一个名为 Tester 的 Java 类。
Tester.java
public class Tester {
public static void main(String args[]) {
//Scenario 1: Only numbers as operands to + operator
System.out.print("Scenario 1: (1 + 2) = ");
System.out.println(1 + 2);
//Scenario 2: Only Strings as operands to + operator
System.out.print("Scenario 2: (\"tutorials\" + \"point.com\") = ");
System.out.println("tutorials" + "points.com");
//Scenario 3: both numbers and strings as operands to + operator
//numbers will be treated as non-text till a string comes
System.out.print("Scenario 3: (1 + 2 + \"tutorials\" + \"point.com\") = ");
System.out.println( 1 + 2 + "tutorials" + "points.com");
//Scenario 4: both numbers and strings as operands to + operator
//if string comes first, numbers will be treated as text.
System.out.print("Scenario 4: (1 + 2 + \"tutorials\" + \"point.com\" + 3 + 4 ) = ");
System.out.println( 1 + 2 + "tutorials" + "points.com" + 3 + 4);
//Scenario 5: both numbers and strings as operands to + operator
//if string comes first, numbers will be treated as text.
//Use brackets to treat all numbers as non-text
System.out.print("Scenario 5: (1 + 2 + \"tutorials\" + \"point.com\" + (3 + 4)) = ");
System.out.println( 1 + 2 + "tutorials" + "points.com" + (3 + 4));
}
}输出
编译并运行文件以验证结果。
Scenario 1: (1 + 2) = 3
Scenario 2: ("tutorials" + "point.com") = tutorialspoints.com
Scenario 3: (1 + 2 + "tutorials" + "point.com") = 3tutorialspoints.com
Scenario 4: (1 + 2 + "tutorials" + "point.com" + 3 + 4 ) = 3tutorialspoints.com34
Scenario 5: (1 + 2 + "tutorials" + "point.com" + (3 + 4)) = 3tutorialspoints.com7
更新于：2020 年 6 月 18 日
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