class Person {

 String name;

 int birthYear;

 byte[] raw;

 

 public boolean equals(Object obj) {

  if (!obj instanceof Person)

   return false;

 

  Person other = (Person)obj;

  return name.equals(other.name)

    && birthYear == other.birthYear

    && Arrays.equals(raw, other.raw);

 }

 

 public int hashCode() { ... }

}

class Person {

 String a;

 Object b;

 byte c;

 int[] d;

 

 public int hashCode() {

  return a.hashCode() + b.hashCode() + c + Arrays.hashCode(d);

 }

 

 public boolean equals(Object o) { ... }

}

class Person implements Comparable<Person> {

 String firstName;

 String lastName;

 int birthdate;

 

 // Compare by firstName, break ties by lastName, finally break ties by birthdate

 public int compareTo(Person other) {

  if (firstName.compareTo(other.firstName) != 0)

   return firstName.compareTo(other.firstName);

  else if (lastName.compareTo(other.lastName) != 0)

   return lastName.compareTo(other.lastName);

  else if (birthdate < other.birthdate)

   return -1;

  else if (birthdate > other.birthdate)

   return 1;

  else

   return 0;

 }

}

 class Values implements Cloneable {

 String abc;

 double foo;

 int[] bars;

 Date hired;

 

 public Values clone() {

  try {

   Values result = (Values)super.clone();

   result.bars = result.bars.clone();

   result.hired = result.hired.clone();

   return result;

  } catch (CloneNotSupportedException e) { // Impossible

   throw new AssertionError(e);

  }

 }

}

int factorial(int n) {

 if (n < 0)

  throw new IllegalArgumentException("Undefined");

 else if (n >= 13)

  throw new ArithmeticException("Result overflow");

 else if (n == 0)

  return 1;

 else

  return n * factorial(n - 1);

}

int findIndex(List<String> list, String target) {

 if (list == null || target == null)

  throw new NullPointerException();

 ...

}

void frob(byte[] b, int index) {

 if (b == null)

  throw new NullPointerException();

 if (index < 0 || index >= b.length)

  throw new IndexOutOfBoundsException();

 ...

}

void frob(byte[] b, int off, int len) {

 if (b == null)

  throw new NullPointerException();

 if (off < 0 || off > b.length

  || len < 0 || b.length - off < len)

  throw new IndexOutOfBoundsException();

 ...

}

// Fill each element of array 'a' with 123

byte[] a = (...);

for (int i = 0; i < a.length; i++)

 a[i] = 123;

（优先）使用标准库的方法：

Arrays.fill(a, (byte)123);

// Copy 8 elements from array 'a' starting at offset 3

// to array 'b' starting at offset 6,

// assuming 'a' and 'b' are distinct arrays

byte[] a = (...);

byte[] b = (...);

for (int i = 0; i < 8; i++)

 b[6 + i] = a[3 + i];

（优先）使用标准库的方法：

System.arraycopy(a, 3, b, 6, 8);

// Make array 'a' larger to newLen

byte[] a = (...);

byte[] b = new byte[newLen];

for (int i = 0; i < a.length; i++) // Goes up to length of A

 b[i] = a[i];

a = b;

// Make array 'a' smaller to newLen
byte[] a = (...);
byte[] b = new byte[newLen];
for (int i = 0; i < b.length; i++) // Goes up to length of B
 b[i] = a[i];
a = b;

1a = Arrays.copyOf(a, newLen);

int packBigEndian(byte[] b) {

 return (b[0] & 0xFF) << 24

    | (b[1] & 0xFF) << 16

    | (b[2] & 0xFF) << 8

    | (b[3] & 0xFF) << 0;

}

 

int packLittleEndian(byte[] b) {

 return (b[0] & 0xFF) << 0

    | (b[1] & 0xFF) << 8

    | (b[2] & 0xFF) << 16

    | (b[3] & 0xFF) << 24;

}

byte[] unpackBigEndian(int x) {

 return new byte[] {

  (byte)(x >>> 24),

  (byte)(x >>> 16),

  (byte)(x >>> 8),

  (byte)(x >>> 0)

 };

}

 

byte[] unpackLittleEndian(int x) {

 return new byte[] {

  (byte)(x >>> 0),

  (byte)(x >>> 8),

  (byte)(x >>> 16),

  (byte)(x >>> 24)

 };

}