Java - assert does not seem to be executed - java

I do not understand why the output of this code is -10:
public class Prova {
public void sip(int i){
assert i>=0 : err();
System.out.println(i);
}
public int err(){
...
}
public static void main(String[] args) {
Prova t = new Prova();
t.sip(-10);
}
}
I thought assert would launch err();

Related

Java boolean static error

The code gives a boolean error when I try to run it. It says boolean can not be adressed with static. What could be the answer.?
package csd;
class Uti {
public static void main(String[] args) {
boolean result;
result = Sample.foo() && Sample.bar();
System.out.printf("result%b%n",result);
}
class Sample {
public static boolean foo() {
System.out.println("foo");
return true;
}
public static boolean bar() {
System.out.println("bar");
return false;
}
}
}
Error message:
Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method foo cannot be declared static; static methods can only be declared in a static or top level type

Making your Sample class static will resolve your error:
class Uti {
public static void main(String[] args)
{
boolean result;
result = Sample.foo() && Sample.bar();
System.out.printf("result%b%n",result);
}
static class Sample {
public static boolean foo() {
System.out.println("foo");
return true;
}
public static boolean bar()
{
System.out.println("bar");
return false;
}
}
}
Making it a top level class will also work:
class Sample {
public static boolean foo() {
System.out.println("foo");
return true;
}
public static boolean bar()
{
System.out.println("bar");
return false;
}
}
class Uti {
public static void main(String[] args)
{
boolean result;
result = Sample.foo() && Sample.bar();
System.out.printf("result%b%n",result);
}
}

Well there is a compilation error in your code, you can fix your problem by adding a static modifier to parent type like this in your code:
public static void main(String[] args)
{
boolean result;
result = Sample.foo() && Sample.bar();
System.out.printf("result%b%n",result);
}
static class Sample {
public static boolean foo() {
System.out.println("foo");
return true;
}
public static boolean bar()
{
System.out.println("bar");
return false;
}
}

I wrote a method to count positive numbers, but how to call that in main method

public class positiveCount {
private static int countPositive(int[] elems) {
int positive = 0;
for (int i=0;i<elems.length;i++) {
if (elems[i] > 0){
positive++;
}
}
return positive;
}
//This gives me the number of the positive numbers.
public static void main(String[] args) {
}
}
in the main method, i want to enter a list, for example {3,4,5,-2,-3,0},how to call the method positveCount

If the main method is in the same class :
public static void main(String[] args) {
countPositive(new int[] {3,4,5,-2,-3,0});
}
Else (works also for case 1) :
public static void main(String[] args) {
PositiveCount.countPositive(new int[] {3,4,5,-2,-3,0});
}

Finding ConnectivityNumber algorithm

I want find Connectivity number in Java. when i try to execute code,any message is not shown(empty)in console. no error message in window o.s. program execute well but when i try again in Linux, error message is shown that no suitabe method 'main' in class.
ConnectivityNumber.java
public class ConnectivityNumber
{
final private int graph[][]={
{0,1,0,1,0,0,0,0,0,0},
{1,0,1,0,0,0,0,0,0,0},
{0,1,0,1,0,0,0,0,0,0},
{1,0,1,0,0,0,0,0,0,0},
{0,0,0,0,0,1,0,0,0,0},
{0,0,0,0,1,0,1,0,0,0},
{0,0,0,0,0,1,0,1,1,0},
{0,0,0,0,0,0,1,0,1,0},
{0,0,0,0,0,0,1,1,0,0},
{0,0,0,0,0,0,0,0,0,0}
};
private int vertex[]={1,0,0,0,0,0,0,0,0,0};
private int connectivityNum=0;
private int startVertex=0;
public boolean isFinishCount()
{
for(int i=0;i<vertex.length;i++)
{
if(vertex[i]==0)
return false;
}
return true;
}
public void randomChoose()
{
for(int i=0;i<vertex.length;i++)
{
if(vertex[i]==0)
startVertex=i;
}
}
public void chooseVertex(int index)
{
startVertex=index;
if(vertex[index]==1)
{
connectivityNum++;
randomChoose();
}
else
{
vertex[index]=1;
}
}
public void rowSearch(int row)
{
for(int i=0;i<vertex.length;i++)
{
if(graph[row][i]==1&&vertex[i]==0)
{
chooseVertex(i);
break;
}
}
}
public void findConnectivityNum()
{
while(!isFinishCount())
{
rowSearch(startVertex);
}
}
public void printConnectivityNum()
{
System.out.println(connectivityNum);
}
}
ConnectivityNumberTest.java
public class ConnectivityNumberTest
{
public static void main(String[] args)
{
ConnectivityNumber connect=new ConnectivityNumber();
connect.findConnectivityNum();
connect.printConnectivityNum();
}
}

For_Loop class is not working as expected on eclipse

My For loop is not working and my print statement (i) is showing error in eclipse
Following is the code.
public class For_Loop {
public static void main(String[] args) {
for (int i = 0; i < 10; i++);
System.out.println(i);
}
}

Remove the ; at end of for
public class For_Loop {
public static void main(String[] args) {
for (int i=0;i<10;i++){
System.out.println(i);
}
}
}

Please remove the semicolon from for loop.
public class For_Loop {
public static void main(String[] args) {
for (int i=0;i<10;i++)
System.out.println(i);
}
}

Code exits without printing expected result

I cannot figure this out for the life of me. I have a very simple piece of code that keeps terminating on the console window.
public class IsUnique {
public int add(){
return 4;
}
public static void main(String[] args){
IsUnique a = new IsUnique();
a.add();
}
}

public class IsUnique {
public int add(){
return 4;
}
public static void main(String[] args){
IsUnique a = new IsUnique();
a.add();
System.out.println(a);
// Wait until user hits key before quitting
System.in.read();
}
}

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