---------------------------------------

double[] a;

---------------------------------------

a = new double[20];

---------------------------------------

double[] temperatura;
temperatura = new double[366];

---------------------------------------

double[] temperatura;
...
temperatura = new double[365];

---------------------------------------

double min, max, media;
double[] temperature;
temperature = new double[366];
int i;

---------------------------------------

min = temperature[1];
max = temperature[1];
media = 0;
for (i = 1; i <= temperature.length - 1; i++) {
  if (temperature[i] < min)
    min = temperature[i];
  if (temperature[i] > max)
    max = temperature[i];
  media = media + temperature[i];
}
media = media/temperature.length;

---------------------------------------

int[] a1;
int i;
char[] a2, a3;
char c;
double[] a4;

---------------------------------------

int a1[], i;
char a2[], a3[], c;
double a4[];

---------------------------------------

a1 = new int[10];
a2 = new char[12];
a3 = new char[5];
a4 = new double[7];

---------------------------------------

int a1[] = new int[10], i;
char a2[] = new char[12], a3[] = new char[5], c;
double[] a4 = new double[7];

---------------------------------------

int[] giorniMese =
         {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

---------------------------------------

int[] giorniMese;
giorniMese = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

---------------------------------------

int[] giorniMese;
giorniMese = 
  new int[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

---------------------------------------

a1[4] = 5;
if (a1[4] > i) {
  a2[10] = 'p';
  a4[0] = a4[1];
}

---------------------------------------

char[] a = new char[12];
char[] b = {'a', 's', 'd'};
System.out.println(a.length);
System.out.println(b.length);

---------------------------------------

for (int i = 0; i <= a.length - 1; i++)
  a[i] = 0;

---------------------------------------

for (int i = 0; i <= a.length - 1; i++)
  a[i] = i;

---------------------------------------

for (int i = 0; i <= a.length - 1; i++)
  a[i]++; // oppure ++a[i]

---------------------------------------

char[] a = new char[10];
for (int i = 0; i <= a.length - 1; i++)
  a[i] = (char) System.in.read();

---------------------------------------

Incompatible type for =. Explicit cast needed to convert int 
to char.
  a[i] =  System.in.read();
       ^
1 error

---------------------------------------

import java.io.*;
class Prova {
  public static void main (String[] args) throws IOException {
    int[] a = new int[10];
    for (int i = 0; i <= a.length - 1; i++)
      a[i] =  System.in.read();
    for (int i = 0; i <= a.length - 1; i++)
      System.out.println(a[i]);
  }
}

---------------------------------------

import java.io.*;
class Prova {
  public static void main (String[] args) throws IOException {
    int[] a = new int[10];
    for (int i = 0; i <= a.length - 1; i++)
      a[i] =  System.in.read();
    for (int i = 0; i <= a.length - 1; i++)
      System.out.println((char)a[i] + " " + a[i]);
  }
}

---------------------------------------

int[] a =  new int[10];

---------------------------------------

final int N = 10;
int[] a =  new int[N];

---------------------------------------

double[][] temperatura2 = new double[13][32];

---------------------------------------

int[] giorniMese =
         {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

---------------------------------------

double[][][][] temperatura4 = double[25][32][13][2001]

---------------------------------------

double[][] a2 = { {20.0, 19.3, 23.4}, {15.3, 16.0, 17.0} };

---------------------------------------

int[][][] ragged = { {1,2,3},{4},{5,6,7,8,9}};

---------------------------------------

/* Programma per invertire un array */
class InversioneArray {
  public static void main (String[] args) {
    int temp, i, a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
    for (i = 0; i <= (a.length - 1) / 2; i++) {
      temp = a[i];
      a[i] = a[a.length - 1 - i];
      a[a.length - 1 - i] = temp;
    }
    for (i = 0; i <= a.length - 1; i++)
      System.out.println(a[i]);
  }
}

---------------------------------------

for (i = 0; i < frequenze.length; i++) {
  "Stampa tanti asterischi quanti frequenze[i]"
  "Vai a capo";
}

---------------------------------------

/* Programma per disegnare l'istogramma di un array di interi*/
class Istogramma {
  public static void main (String[] args) {
    int i, j;
    int[] frequenze = {3, 5, 9, 6, 7, 1, 20, 5, 9, 4, 3, 2};

    for (i = 0; i < frequenze.length; i++) {
      System.out.print(i);
      System.out.print(": \t");
      for (j = 1; j <= frequenze[i]; j++)
        System.out.print('*');
      System.out.println();
    }
  }
}

---------------------------------------

0:      ***
1:      *****
2:      *********
3:      ******
4:      *******
5:      *
6:      ********************
7:      *****
8:      *********
9:      ****
10:     ***
11:     **

---------------------------------------

trovato = false;
for (i = 0; i < a.length; i++)
  if (a[i] == x) {
    trovato = true;
    break;
  }
if (trovato)
  System.out.println(i);
else
  System.out.println("Elemento non trovato");

---------------------------------------

/* Ordinamento per selezione */
import java.io.*; 
class OrdinamentoSelezione { 
  public static void main (String[] args) throws IOException { 
    final int N = 10; 
    char temp, a[] = new char[N];

    for (int i = 0; i < N; i++)
      a[i] = (char) System.in.read();
    for (int i = 0; i < N - 1; i++)
      for (int j = i; j < N; j++)
        if (a[i] > a[j]) {
          temp = a[i];
          a[i] = a[j];
          a[j] = temp;
        }
    for (int i = 0; i < N; i++)
      System.out.print(a[i]);
  }
}

---------------------------------------

>javac OrdinamentoSelezione.java
>java OrdinamentoSelezione
cladbiehfm
abcdefhilm

---------------------------------------

/* Ricerca Binaria. Assume che l'array a sia ordinato */
import java.io.*;
class RicercaBinaria {
  public static void main (String[] args) throws IOException {
    final int N = 10;
    int p, q, m;
    char x;
    char[] a = 
      {'a', 'b', 'c', 'd', 'f', 'g', 'h', 'i', 'j', 'k'};
    for (int i = 0; i < N; i++)
      System.out.print(a[i]);
    System.out.print("\nInserisci l'elemento da trovare: ");
    x = (char) System.in.read();
    p = 0;
    q = N - 1;
    System.out.println("p\tm\tq");
    do {
      m = (p + q) / 2;
      System.out.println(p + "\t" + "\t" + q);
      System.out.println("\t" + m);
      if (a[m] < x)
        p = m + 1;
      if (a[m] > x)
        q = m - 1;
    } while (a[m] != x && p <= q);
    if (a[m] == x)
      System.out.println(x + " trovato in posizione " + m);
    else
      System.out.println(x + " non trovato");
  }
}

---------------------------------------

>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: k
p       m       q
0               9
        4
5               9
        7
8               9
        8
9               9
        9
k trovato in posizione 9
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: a
p       m       q
0               9
        4
0               3
        1
0               0
        0
a trovato in posizione 0
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: f
p       m       q
0               9
        4
f trovato in posizione 4
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: g
p       m       q
0               9
        4
5               9
        7
5               6
        5
g trovato in posizione 5
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: e
p       m       q
0               9
        4
0               3
        1
2               3
        2
3               3
        3
e non trovato
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: q
p       m       q
0               9
        4
5               9
        7
8               9
        8
9               9
        9
q non trovato
>java RicercaBinaria
abcdfghijk
Inserisci l'elemento da trovare: A
p       m       q
0               9
        4
0               3
        1
0               0
        0
A non trovato

---------------------------------------

for (i = 0; i < N; i++)
  for (j = 0; j < N; j++)
    C[i,j] = 0;
for (i = 0; i < N; i++)
  for (j = 0; j < N; j++)
    for (k = 0; k < M; k++)
      C[i,j] = C[i,j] + A[i,k] * B[k,j];