01.异常处理

1.1 try catch

public class Test{
    public static void main( String args[] ) {
        try {
            int[] myNumbers = {1, 2, 3};
            System.out.println(myNumbers[8]);
        } catch (Exception e) {
            System.out.println(e);  // java.lang.ArrayIndexOutOfBoundsException: 8
        }
    }
}

1.2 finally

• finally语句可以在try catch之后执行代码，而不管是否在try代码中出现异常

public class Test{
    public static void main( String args[] ) {
        try {
            int[] myNumbers = {1, 2, 3};
            System.out.println(myNumbers[8]);
        } catch (Exception e) {
            System.out.println("输出异常信息等其它操作");
        } finally {
            System.out.println("执行资源释放等相关代码");
        }
    }
}

1.3 throw

• throw语句用于创建抛出自定义错误，throw语句与异常类型一起使用
• Java中提供了许多异常类型
  • ArithmeticException，FileNotFoundException，ArrayIndexOutOfBoundsException，SecurityException

public class Test{
    public static void main(String[] args) {
        checkValue(-2);
    }

    static void checkValue(int x) {
        if (x < 0) {
            throw new ArithmeticException("error is x < 0");
        }
        else {
            System.out.println("x > 0");
        }
    }
}
/*
Exception in thread "main" java.lang.ArithmeticException: error is x < 0
	at com.case_01.Test.checkValue(Test.java:10)
	at com.case_01.Test.main(Test.java:5)
 */