解析Java中未被捕获的异常以及try语句的嵌套使用

class Exc0 {
  public static void main(String args[]) {
    int d = 0;
    int a = 42 / d;
  }
}

  java.lang.ArithmeticException: / by zero
  at Exc0.main(Exc0.java:4)

class Exc1 {
  static void subroutine() {
    int d = 0;
    int a = 10 / d;
  }
  public static void main(String args[]) {
    Exc1.subroutine();
  }
}

  java.lang.ArithmeticException: / by zero
  at Exc1.subroutine(Exc1.java:4)
  at Exc1.main(Exc1.java:7)

// An example of nested try statements.
class NestTry {
  public static void main(String args[]) {
    try {
      int a = args.length;
      /* If no command-line args are present,the following statement will generate a divide-by-zero exception. */
      int b = 42 / a;
      System.out.println("a = " + a);
      try { // nested try block
        /* If one command-line arg is used,then a divide-by-zero exception will be generated by the following code. */
        if(a==1) a = a/(a-a); // division by zero
        /* If two command-line args are used,then generate an out-of-bounds exception. */
        if(a==2) {
          int c[] = { 1 };
          c[42] = 99; // generate an out-of-bounds exception
        }
      } catch(ArrayIndexOutOfBoundsException e) {
        System.out.println("Array index out-of-bounds: " + e);
      }
    } catch(ArithmeticException e) {
      System.out.println("Divide by 0: " + e);
    }
  }
}

C:\>java NestTry
Divide by 0: java.lang.ArithmeticException: / by zero
C:\>java NestTry One
a = 1
Divide by 0: java.lang.ArithmeticException: / by zero
C:\>java NestTry One Two
a = 2
Array index out-of-bounds: java.lang.ArrayIndexOutOfBoundsException

/* Try statements can be implicitly nested via calls to methods. */
class MethNestTry {
  static void nesttry(int a) {
    try { // nested try block
      /* If one command-line arg is used,then a divide-by-zero exception will be generated by the following code. */
      if(a==1) a = a/(a-a); // division by zero
      /* If two command-line args are used,then generate an out-of-bounds exception. */
      if(a==2) {
        int c[] = { 1 };
        c[42] = 99; // generate an out-of-bounds exception
      }
    } catch(ArrayIndexOutOfBoundsException e) {
      System.out.println("Array index out-of-bounds: " + e);
    }
  }

  public static void main(String args[]) {
    try {
      int a = args.length;
      /* If no command-line args are present,the following statement will generate a divide-by-zero exception. */
      int b = 42 / a;
      System.out.println("a = " + a);
      nesttry(a);
    } catch(ArithmeticException e) {
      System.out.println("Divide by 0: " + e);
    }
  }
}