We Keep Coding

Execute code only if one of the if statements ran

Take a look at this example code.
boolean check = false;
if (condition) {
do x;
check = true;
}
else if (condition2) {
do y;
check = true;
}
else if (condition3) {
do z;
check = true;
}
if (check) {
do a;
} else {
do b;
}
There has to be a better way to do this than a boolean variable, no? I mean it works, but it looks kind of messy to me.

Logically, you could put a in each of the if conditions and add a single final else for b. Like,
if (condition) {
do x;
do a;
} else if (condition2) {
do y;
do a;
} else if (condition3) {
do z;
do a;
} else {
do b;
}

You could write it this way if you prefer:
if (condition) {
do x;
} else if (condition2) {
do y;
} else if (condition3) {
do z;
} else {
do b;
return;
}
do a;
Whether that makes sense for your context depends on what all these a, b, condition etc. actually are.
If you can't use return, you could at least reduce the number of places you're setting your boolean variable:
boolean check = true;
if (condition) {
do x;
} else if (condition2) {
do y;
} else if (condition3) {
do z;
} else {
do b;
check = false;
}
if (check) {
do a;
}

I would propose to define your business logic of actions x, y etc.. as separate classes or functional implementations of the interface Action with a single method execute()
Your codebase will be replaced with something similar:
#FunctionalInterface
public interface Action {
void execute();
}
Action action =
condition1 ? () -> System.out.println("Action X") :
condition2 ? () -> System.out.println("Action Y") : null;
if (Objects.nonNull(action)) {
action.execute();
((Action) () -> System.out.println("Action A")).execute();
} else {
((Action) () -> System.out.println("Action B")).execute();
}

Binary search tree String search

I have a program where I need to search for a specific word in a binary tree, the code I came up with for the search method for the string is not working. if someone could take a look at it I would greatly appreciate it.
I have tried a few alterations to this but it still did not work.
public boolean check(BSTNode t,String key){
if(!t.word.equals(key)){
check(t.left,key);
check(t.right,key);
}
else{
return true;
}
return false;
}

This could be written like this;
public boolean check(BSTNode t,String key) {
return
t.word.equals(key) || check(t.left,key) || check(t.right,key)
}
or, more verbosely;
public boolean check(BSTNode t,String key) {
if (t.word.equals(key)) return true;
if (check(t.left,key)) return true;
if (check(t.right,key)) return true;
return false;
}
You don't need a lot of else statements because the return statements stop execution in the function.
Edit:
You must also check to see that your BSTNode is not null, or you will get null pointer exceptions when you reach the end of the tree. This could be done at the start of the function, or before the inner recursive check calls:
public boolean check(BSTNode t,String key) {
if (t == null) return false;
if (t.word.equals(key)) return true;
if (check(t.left,key)) return true;
if (check(t.right,key)) return true;
return false;
}
or;
public boolean check(BSTNode t,String key) {
if (t.word.equals(key)) return true;
if (t.left != null && check(t.left,key)) return true;
if (t.right != null && check(t.right,key)) return true;
return false;
}

returning true with an occurance of a letter in a string?

it should return true as there is 'c' in the string S but it keeps returning False?
public class A {
public static void main(String[] args){
System.out.println(contains('c', "cccc"));
}
public static boolean contains(char c, String s) {
boolean to_return = true;
while(true) {
if(s.equals("")){
return to_return = false;
} else {
char c2 = s.charAt(0);
if(c==c2) {
to_return = true;
}
}
s=s.substring(1);
}
}
}
I have NO idea why it isnt? it only returns false if the string is empty which is clearly is(I am NOT allowed to use for loops etc..

you are not returning true anywhere in your code. So recursion happens till s.equals("") is evaluated to true and returns false.
Change
if(c==c2) {
to_return = true;
}
to
if(c==c2) {
return true;
}

works:
public static boolean contains(char c, String s) {
return s.indexOf(c) != -1;
}

If you want a loopy version, use a for loop like this, as it should be cleaner:
public static boolean contains(char c, String s) {
boolean to_return = true;
for(int i=0;i<s.length();i++) {
if(s.charAt(i) != c) {
to_return = false;
}
}
return to_return;
}
Alternatively, you can just do:
public static boolean contains2(char c, String s) {
return s.contains(String.valueOf(c));
}

Can you try a more cleaner method, it seems too cluttered.
public static boolean contains(char c, String s) {
if (s == null)
return false;
if (s.equals(""))
return false;
int size = s.length();
for (int i = 0; i < size; i ++) {
if(s.charAt(i) == c)
return true;
}
return false;
}

Long list of if comparisons in java

I need to compare two Objects. If there is a difference I need to log it corresponding to particular difference and return the true.
For example:
private boolean compTwoObjects(Object objA, Object ObjB) {
if(objA.getType() != objB.getType()) {
logTheDifference("getType is differing");
return true;
}
.
.
.
// Now this could invoke other composite methods
if(checkFont(objA.getFont(), objB.getFont()) {
logTheDifference("Font is differing");
return true;
}
}
private boolean checkFont(Font fontObjA, Font fontObjB) {
if(fontObjA.getBold() != fontObjB.getBold()) {
logTheDifference("font bold formatting differs");
return true;
}
.
.
.
if(fontObjA.getAllCaps() != fontObjB.getAllCaps()) {
logTheDifference("font all caps formatting differs");
return true;
}
.
.
.
if(checkBorderDiff(fontObjA.getBorder(), fontObjB.getBorder())) {
logTheDifference("border diff");
return true;
}
}
private boolean checkBorderDiff(Border borderObjA, Border borderObjB) {
if (borderObjA.getColor() != null || borderObjB.getColor() != null) {
if (!borderObjA.getColor().equals(borderObjB.getColor())) {
logIt("border color differing");
return true;
}
}
if (borderObjA.getDistanceFromText() != borderObjB.getDistanceFromText()) {
logIt("distance of the border from text or from the page edge in points differing");
return true;
}
if (borderObjA.isVisible() != borderObjB.isVisible()) {
logIt("border visibility differing");
return true;
}
if (borderObjA.getLineStyle() != borderObjB.getLineStyle()) {
logIt("line style differing for border");
return true;
}
if (borderObjA.getLineWidth() != borderObjB.getLineWidth()) {
logIt("border width in points differing");
return true;
}
if (borderObjA.getShadow() != borderObjB.getShadow()) {
logIt("border shadow differing");
return true;
}
}
//And it is going like this.
My problem is I want to avoid multiple if statements in the methods. Also I want to log the messages corresponding to particular difference.
I have read few similar type of problems on stackoverflow solved either by command pattern or HashMap. But they don't include comparisons in that.
I want to refactor my code to get rid of series of if's.

Have a system of comparators, backed by generics. Every comparer will also know what is next in line. For example:
interface IComparer<T> {
boolean areDifferent (T first, T second);
}
class FontComparer implements IComparer<Font> {
#Override
public boolean areDifferent(Font first, Font second) {
// Compare fonts start
// ..
// Compare fonts end
return new BorderComparer().areDifferent(first.getBorder(), second.getBorder());
}
}
class BorderComparer implements IComparer<Border> {
#Override
public boolean areDifferent(Border first, Border second) {
//Do border comparison alone
return false;
}
}
You could setup a comparer chain now, and bail out when comparison fails. Otherwise, comparison goes to the comparer next in the chain.
The client code will finally look like:
Object one = new Object();
Object two = new Object();
new ObjectComparer().areDifferent(one, two);

Have you considered enums?
private enum FontCmp {
Bold {
#Override
boolean cmp(Font a, Font b) {
return a.getBold() != b.getBold();
}
},
AllCaps {
#Override
boolean cmp(Font a, Font b) {
return a.getAllCaps() != b.getAllCaps();
}
},
Border {
#Override
boolean cmp(Font a, Font b) {
return BorderCmp.compare(a.getBorder(), b.getBorder());
}
};
// Each enum has one of these.
abstract boolean cmp(Font a, Font b);
// Compare them all and log any failures.
static boolean compare(Font a, Font b) {
for (FontCmp c : FontCmp.values()) {
if (c.cmp(a, b)) {
logIt("FontCmp-" + c + " failed");
return false;
}
}
return true;
}
}

You could also use reflection as described here. Also look into introspection as described here

Fundamentally you are trying to do a series of comparisons, so there is little choice but to do a series of comparisons.
What you could do is define an interface/enum/abstract class which is a FieldChecker. That FieldChecker would have an abstract method implemented differently in each FieldChecker:
String performCheck(Font a, Font b) {
if (DO CHECK HERE) {
return "failure message";
}
return null;
}
Then your check function just becomes:
for (FieldChecker fc: fieldCheckers) {
String res = fc.performCheck(a,b);
if (res != null) {
return res;
}
}
return "All ok";

Exception in thread "main" StackoverFlow error

I am writing a program that verifies if a password meets the appropriate requirements. I have all of my code written, and I feel it should work, but I get the following error:
Exception in thread "main" java.lang.StackOverflowError
at java.lang.String.length(String.java:623)
at PasswordVerifier.isValid(PasswordVerifier.java:5)
at PasswordVerifier.isValid(PasswordVerifier.java:6)
and then it repeats the last line of the error for quite some time. I've been looking around and cannot seem to figure out my issue. I know something is continually looping that I don't want to, but the fix eludes me. Here is my code
public class PasswordVerifier{
private static int MIN_PASSWORD_LENGTH = 6;
public static boolean isValid(String str){
if (str.length() >= MIN_PASSWORD_LENGTH){
if (PasswordVerifier.isValid(str) == true){
if (PasswordVerifier.hasUpperCase(str) == true){
if (PasswordVerifier.hasLowerCase(str) == true){
if (PasswordVerifier.hasDigit(str) == true){
return true;
}
}
}
}
}
return false;
}
private static boolean hasUpperCase(String str){
for (char c : str.toCharArray()){
if (Character.isUpperCase(c)){
return true;
}
}
return false;
}
private static boolean hasLowerCase(String str){
for (char c : str.toCharArray()){
if (Character.isLowerCase(c)){
return true;
}
}
return false;
}
private static boolean hasDigit(String str){
for (char c : str.toCharArray()){
if (Character.isDigit(c)){
return true;
}
}
return false;
}
}
Any help would be appreciated!

public static boolean isValid(String str){
// ...
if (PasswordVerifier.isValid(str) == true){
// ...
}
// ...
}
You're calling isValid(String) from within itself, which is causing the infinite loop recursion.
I'm going to take a wild guess and say this is what you want instead:
public static boolean isValid(String str){
if (str.length() >= MIN_PASSWORD_LENGTH){
// Removed call to .isValid(String)
if (PasswordVerifier.hasUpperCase(str)){
if (PasswordVerifier.hasLowerCase(str)){
if (PasswordVerifier.hasDigit(str)){
return true;
}
}
}
}
return false;
}