Java Code to Compare Arrays :java.util.Arrays

// null arrays are equal
boolean[] bArr1 = null;
boolean[] bArr2 = null;
boolean b = Arrays.equals(bArr1, bArr2); // true

// Compare two boolean arrays
bArr1 = new boolean[]{true, false};
bArr2 = new boolean[]{true, false};
b = Arrays.equals(bArr1, null); // false
b = Arrays.equals(bArr1, bArr2); // true

// There are equals() methods for all eight primitive types
b = Arrays.equals(new byte[]{0}, new byte[]{0}); // true
b = Arrays.equals(new char[]{'a'}, new char[]{'a'}); // true
b = Arrays.equals(new short[]{0}, new short[]{0}); // true
b = Arrays.equals(new int[]{0}, new int[]{0}); // true
b = Arrays.equals(new long[]{0L}, new long[]{0L}); // true
b = Arrays.equals(new float[]{0F}, new float[]{0F}); // true
b = Arrays.equals(new double[]{0D}, new double[]{0D}); // true

// When comparing Object arrays, null elements are equal.
// If the elements are not null, Object.equals() is used.
b = Arrays.equals(new String[]{"a"}, new String[]{"a"}); // true
b = Arrays.equals(new String[]{null}, new String[]{null}); // true
b = Arrays.equals(new String[]{"a"}, new String[]{null}); // false

Java Code to Convert a Collection to an Array : java.util.Arrays

// Create an array containing the elements in a list
Object[] objectArray = list.toArray();
MyClass[] array = (MyClass[])list.toArray(new MyClass[list.size()]);

// Create an array containing the elements in a set
objectArray = set.toArray();
array = (MyClass[])set.toArray(new MyClass[set.size()]);

// Create an array containing the keys in a map
objectArray = map.keySet().toArray();
array = (MyClass[])map.keySet().toArray(new MyClass[set.size()]);

// Create an array containing the values in a map
objectArray = map.values().toArray();
array = (MyClass[])map.values().toArray(new MyClass[set.size()]);
Related Examples

Java Code to Shuffle the Elements of a List or Array : java.util.Arrays

Use Collections.shuffle() to randomly reorder the elements in a list.
// Create a list
List list = new ArrayList();

// Add elements to list

// Shuffle the elements in the list
Collections.shuffle(list);

// Create an array
String[] array = new String[]{"a", "b", "c"};

// Shuffle the elements in the array
Collections.shuffle(Arrays.asList(array));

Java Code to Compare Arrays : java.util.Arrays

// null arrays are equal
boolean[] bArr1 = null;
boolean[] bArr2 = null;
boolean b = Arrays.equals(bArr1, bArr2); // true

// Compare two boolean arrays
bArr1 = new boolean[]{true, false};
bArr2 = new boolean[]{true, false};
b = Arrays.equals(bArr1, null); // false
b = Arrays.equals(bArr1, bArr2); // true

// There are equals() methods for all eight primitive types
b = Arrays.equals(new byte[]{0}, new byte[]{0}); // true
b = Arrays.equals(new char[]{'a'}, new char[]{'a'}); // true
b = Arrays.equals(new short[]{0}, new short[]{0}); // true
b = Arrays.equals(new int[]{0}, new int[]{0}); // true
b = Arrays.equals(new long[]{0L}, new long[]{0L}); // true
b = Arrays.equals(new float[]{0F}, new float[]{0F}); // true
b = Arrays.equals(new double[]{0D}, new double[]{0D}); // true

// When comparing Object arrays, null elements are equal.
// If the elements are not null, Object.equals() is used.
b = Arrays.equals(new String[]{"a"}, new String[]{"a"}); // true
b = Arrays.equals(new String[]{null}, new String[]{null}); // true
b = Arrays.equals(new String[]{"a"}, new String[]{null}); // false