1. Example 1
//try-catch handles exceptions
public class Error { public static void main(String[] args) { int num1=34,num2=0; //使用try包裹住会产生异常的代码段 try{ System.out.println(num1/num2); } //使用catch去处理对应的异常 catch(ArithmeticException error){ //处理方法 System.err.println("运算错误,除数不能为0!"); } System.out.println("程序运行结束!"); } }
Result verification:
Operation error, the divisor cannot be 0!
The program is finished!
2. Example 2
import java.util.InputMismatchException; import java.util.Scanner; public class Error { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("请输入第一个数字:"); //使用try包裹住会产生异常的代码段 try{ int num1=input.nextInt(); System.out.println("请输入第二个数字:"); int num2=input.nextInt(); System.out.println(num1/num2); } //使用catch去处理对应的异常 catch(ArithmeticException error1){ //处理方法 System.err.println("运算错误,除数不能为0!"); }catch(InputMismatchException error2){ System.err.println("请输入正确的数字!"); } System.out.println("程序运行结束!"); } }
Result verification:
Result one:
Please enter the first number:
123
Please enter the second number:
123
1
The program is finished!
Result 2:
Please enter the first number:
123
Please enter the second number:
b
Please enter the correct number!
The program is finished!
Result 3:
Please enter the first number:
123
Please enter the second number:
0
Operation error, divisor It cannot be 0!
The program is finished!
3. Example 3
//Convert user input string to integer
3.1
public class Error { String str; public Error(String str) { this.str = str; } public String Transform(){ try{ int num = Integer.parseInt(str); }catch(NumberFormatException num){ System.out.println("字符串转整型,请输入正确的数字:"); }catch(Exception e){ } return str; } }
//Write a test class, call the data type conversion method, and pass the parameters "Good!" and 20
public class ErrorDemo { public static void main(String[] args) { Error er = new Error("Good!"); er.Transform(); System.out.println(er.str); } }
String conversion Integer, please enter the correct number:
Good!
3.2
public class Error { int num = 0; public Error() { } public Error(int num) { this.num = num; } public int TransformtoInt(String str){ try{ int num1 = Integer.parseInt(str); }catch(NumberFormatException num){ System.err.println("字符串转整型,请输入正确的数字:"); }catch(Exception error){ error.printStackTrace(); } return num; } }
import java.util.Scanner; public class ErrorDemo { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("请输入一个数字:"); String str = input.next(); Error toInt = new Error(); toInt.TransformtoInt(str); System.out.println(str); } }
Verification:
Please enter a number:
123
123
Please enter a number:
abc
Convert string to integer, please enter Correct number:
abc
4. Example 4
//[b]throws, throw throws exception[/b]
public class Error { String sex ; public Error() { } public String getSex() { return sex; } public void setSex(String sex) throws Exception { if(sex.equals("男")|sex.equals("女")){ this.sex = sex; }else{ throw new Exception("性别必须为男或者女!"); } } }
public class ErrorDemo { public static void main(String[] args) { Error er = new Error(); try{ er.setSex("熊"); }catch(Exception error){ error.printStackTrace(); } System.out.println("程序结束"); } }
java.lang.Exception: Gender must be male or female!
at Error.setSex(Error.java:22)
at ErrorDemo.main(ErrorDemo.java:9)
End of program
5、
Custom exception
//Create Excption subclass to inherit [b]ExcptionParent class[/b]
//创建类 public class Error { String sex ; public Error() { } public String getSex() { return sex; } public void setSex(String sex) throws Exception { if(sex.equals("男")|sex.equals("女")){ this.sex = sex; }else{ throw new ExceptionDemo("性别必须为男或者女!"); } } }
//创建ExceptionDemo子类 public class ExceptionDemo extends Exception { public ExceptionDemo() { super(); } public ExceptionDemo(String message) { super(message); } }
//创建测试类 import java.util.Scanner; public class ErrorDemo { public static void main(String[] args) { Error er = new Error(); try{ Scanner next = new Scanner(System.in); System.out.println("请输入性别:"); er.setSex(next.next()); }catch(Exception error){ error.printStackTrace(); } System.out.println("程序结束!"); } }
Result verification:
Please enter gender:
Male
End of program!
Please enter your gender:
nan ExceptionDemo: 性别必须为男或者女! at Error.setSex(Error.java:23) at ErrorDemo.main(ErrorDemo.java:10)
The program is over!
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Emerging technologies pose both threats and enhancements to Java's platform independence. 1) Cloud computing and containerization technologies such as Docker enhance Java's platform independence, but need to be optimized to adapt to different cloud environments. 2) WebAssembly compiles Java code through GraalVM, extending its platform independence, but it needs to compete with other languages for performance.

Different JVM implementations can provide platform independence, but their performance is slightly different. 1. OracleHotSpot and OpenJDKJVM perform similarly in platform independence, but OpenJDK may require additional configuration. 2. IBMJ9JVM performs optimization on specific operating systems. 3. GraalVM supports multiple languages and requires additional configuration. 4. AzulZingJVM requires specific platform adjustments.

Platform independence reduces development costs and shortens development time by running the same set of code on multiple operating systems. Specifically, it is manifested as: 1. Reduce development time, only one set of code is required; 2. Reduce maintenance costs and unify the testing process; 3. Quick iteration and team collaboration to simplify the deployment process.


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