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Java: if / else not responding even with no compile errors

I wrote a simple if / else that is supposed to print the answer to the if else. but does not respond even with the correct input. I can't see what I'm missing.
import java.util.Scanner;
public class MarriageQuiz{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
String marStat;
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.nextLine();
marStat = marStat.toUppercase();
if(marStat.equals('M')){
System.out.print("You are married");
}
else if(marStat.equals('S')){
System.out.print("You are single");
}
}
}

Your code is comparing a String object against a character literal, which I believe the JVM will box into a Character object. Well, these two objects don't belong to the same class, so "M".equals('M') will return false. To remedy this, use "M".equals("M").
change toUppercase() to toUpperCase() and marStat.equals('M') to marStat.equals("M") also marStat.equals('S') to marStat.equals("S")
import java.util.Scanner;
public class MarriageQuiz {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String marStat = "";
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.nextLine();
marStat = marStat.toUpperCase();
if (marStat.equals("M")) {
System.out.print("You are married");
} else if (marStat.equals("S")) {
System.out.print("You are single");
}
}
}

On the other hand, you can use Character type instead of 'String'. Rather using Character would be more accurate as you are dealing with only one character.
Scanner input = new Scanner(System.in);
Character marStat;
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.next().charAt(0);
marStat = Character.toUpperCase(marStat);
if (marStat.equals('M')) {
System.out.println("You are married");
} else if (marStat.equals('S')) {
System.out.println("You are single");
}

use ""
if(marStat.equals("M")){
System.out.print("You are married");
}
else if(marStat.equals("S")){
System.out.print("You are single");
}

As mentioned in a comment above, you are comparing a String object to an autoboxed Character object. One fix is obviously using double quotes, which Java will autobox to a String object your code will work.
A few tips to save a few lines of code: use String.equalsIgnoreCase() to save a line converting the incoming string to uppercase.
Next, consider using a constant for marital status:
public class MarriageQuiz{
private static final String STATUS_MARRIED = "M";
...
if (marStat.equalsIgnoreCase(STATUS_MARRIED)) {
...
That way you can use STATUS_MARRIED all over your code but can change it from, say, "M" to "Married" easily.

JAVA - Rock Paper Scissors Lab help! (IF/THENS)

Background: Beginner in programming, very new to this whole "Java" thing.
I love the help, but I do not want a direct answer, more like a point in the right direction, or any which way where I can learn instead of blindly copy/paste. Instead of "heres the right code" more of "hears how you can get the right code"
Thank you :)
Ok so my question is, what is wrong with the prompt ad the IF/THEN statement. When I run it with the prompt, it says cannot find symbol - method prompt(java.lang.String)
Without the prompt, when I run it, after I input my choice, whether right or wrong, it always returns "Sorry, that is'nt a choice. Choose rock, paper or scissors!" even if it is right!
If you need any more info on my problem, let me know :)
Anyway here is the class:
//Player class
import java.util.Scanner;
import java.lang.String;
public class Player
{
private String name;
private String choice;
public Player(String nm)
{
name = nm;
}
public Player(String nm, String ch)
{
name = nm;
choice = ch;
}
public void setName( String nm)
{
name = nm;
}
public void setChoice( String ch )
{
}
public String getChoice()
{
Scanner scan = new Scanner (System.in);
System.out.println("Choose rock, paper or scissors:");
String player = scan.next(); player.toLowerCase();
if ((player != ("rock"))
|| (player != ("paper"))
|| (player != ("scissors")))
{
System.out.println("Sorry, that is'nt a choice. Choose rock, paper or scissors!");
player = prompt("Choose rock, paper or scissors:");
}
else
{
System.out.println("Good choice!");
}
System.out.println("You chose " + player);
return "";
}
public String getName()
{
Scanner scan = new Scanner (System.in);
System.out.println("Whats your name?");
String name = scan.next();
return "";
}
public String toString()
{
return "";
}
}
And the runner:
public class PlayerRunner
{
public static void main(String[] args)
{
Player s = new Player("Michael Jackson", "rock");
System.out.println(s.getChoice());
System.out.println(s.getName());
//outs rock
//call the getName() method
System.out.println(s); //outs Michael Jackson rock
//set the choice to paper
System.out.println(s); //outs Michael Jackson paper
//instantiate a new Player named jb named Jim Bob that chose scissors
//print out Jim Bob
}
}
The goal of this portion was titled to: "Use the Player.java file to create the player. Complete the Player constructors, set
methods, get methods, and the toString. Use PlayerRunner.java to test your Player class."
Let me know if you see that I did anything else wrong :) Again I'm a beginner, but I'm here to learn, not just paste the right answer and move on.
Thank you!!

How about:
public String getChoice() {
Scanner scan = new Scanner(System.in);
System.out.println("Choose rock, paper or scissors:");
String player = scan.next();
while ((!player.equalsIgnoreCase("rock"))
&& !player.equalsIgnoreCase("paper")
&& !player.equalsIgnoreCase("scissors")) {
System.out.println("Sorry, that is'nt a choice. Choose rock, paper or scissors!");
System.out.println("Choose rock, paper or scissors:");
player = scan.next();
}
System.out.println("Good choice!");
System.out.println("You chose " + player);
return "";
}

When you use the == operator, you're comparing whether or not two objects are the same, or whether two primitive type's values are the same.
Since a string is actually an object in Java,
String a = "string";
String b = "string";
System.out.println(a == b);
will return false, but
String a = "string";
String b = a;
System.out.println(a == b);
will return true.
Instead, if you call the equals method of the String class, you can compare whether or not the two values are the same.
String a = "string";
String b = "string";
System.out.println(a.equals(b));
In your case, player != ("rock") will always evaluate as true, which looks to be causing some problems.
You can read more here: Java String.equals versus ==

Boolean Method does not return false

It compiles, just that it doesn't initialize the while (choice = false) so whatever ans was entered, it wouldn't show "Invalid input, enter a, b, c: " and reiterate.
import java.util.Scanner;
public class Test
{
public static void main(String[] args)
{
Scanner kb = new Scanner(System.in);
String ans;
boolean choice;
System.out.print("Enter a, b, c: ");
ans = kb.nextLine();
choice = isValidChoice(ans);
while (choice = false)
{
System.out.print("Invalid input, enter a, b, c: ");
ans = kb.nextLine();
choice = isValidChoice(ans);
}
if (choice = true)
{
System.out.println("Your input was " + ans);
}
}
public static boolean isValidChoice(String choice)
{
if (choice.equalsIgnoreCase("a") || choice.equalsIgnoreCase("a")
|| choice.equalsIgnoreCase("a"))
{
return true;
}
else
{
return false;
}
}
}

Always use == when you need to compare , which means equality in Java, while = means assignment. This is different from some language like PL/SQL.
So when you call while(choice =false), Java only assigns false to variable choice , it does not compare the choice with false.
You should use while(choice==false) instead, the same in if (choice == true)
Check operators for more details

You are using an assignment where you want to use the equals operator. while(!choice) or while(choice==false). Same in if. In your case you need to differentiate between valid and the actual choice. Maybe it is easier to have the function return more values than a boolean.
And a helpful tip: never ignore warnings of the compiler or the IDE. It will tell you if you do something stupid like assigning in an expression.

How do you prompt a user for an input in java

So I just started learning Java, its literally like my 1st day and I wanted to try to make a coinflip game. I already know a decent amount of Javascript and so i was trying to apply that knowledge to java. So everything has been working so far except one thing: Prompting a user for a choice. So read online that i have to import a scanner so i did that as you can see from my code. I also tried some code where you can have the user import a string but you can see a bit later in my program i change the variable userChoice into a number. So basically i just need help with this. If there is some way to have a variable type that can store both numbers or strings that would be best. But im tottaly open to other ways of doing this! Thanks in advanced! Here is the code:
package test;
import java.util.Scanner;
public class testclass {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("hi");
int bob;
bob = (int) Math.floor(Math.random()*2);
System.out.println(bob);
System.out.println("Enter heads or tails?");
System.out.println("You entered "+ userChoice);
if (bob == 0) {
System.out.println("Computer flipped heads");
}
else {
System.out.println("Computer flipped tails");
}
if(userChoice == "Heads") {
userChoice = 0;
}
else {
userChoice = 1;
}
if (userChoice == bob) {
System.out.println("You win!");
}
else {
System.out.println("Sorry you lost!")
}
}
}

Use a scanner, as you said:
Scanner in = new Scanner(System.in);
Then, prompt the user to enter something in:
String userChoice = in.nextLine();
Also, when you compared strings:
if(userChoice == "Heads") {...
that's bad to do for none-primitive objects. It's best to only use the == to compare values that are ints or enums. If you compare a String like this, it won't work, because it's checking if the objects are the same. Instead, compare like this:
if(userChoice.equals("Heads")) {...
Also, to convert to an int (NOTE: You can't convert one type of object to another that aren't related in any way! You'll have to create a new object if you're wanting to do that), do this:
int myInt = Integer.parseInt(myString); // NOTE: Can throw NumberFormatException if non-number character is found.
So your program should look somewhat like:
package test;
import java.util.Scanner;
public class testclass {
public static void main(String[] args) {
//System.out.println("hi");
Scanner in = new Scanner(System.in);
int bob;
int userChoice;
String input;
bob = (int) Math.floor(Math.random()*2);
System.out.println(bob);
System.out.println("Enter heads or tails?");
input = in.nextLine(); // waits for user to press enter.
System.out.println("You entered "+ input);
if (bob == 0) {
System.out.println("Computer flipped heads");
}
else {
System.out.println("Computer flipped tails");
}
if(input.equals("Heads")) {
userChoice = 0;
}
else {
userChoice = 1;
}
if (userChoice == bob) {
System.out.println("You win!");
}
else {
System.out.println("Sorry you lost!");
}
in.close(); // IMPORTANT to prevent memory leaks
}
}

You've already imported the Scanner class so you can now create a variable of the type Scanner for taking inputs.
Scanner in = new Scanner();
userChoice = in.nextLine();
nextLine() can be used to input a character or a string from the user.
To convert the string into a integer, You can assign the integer value to the string in the following way.
if(userChoice == "Heads") {
userChoice = "" + 0;
}
else {
userChoice = "" + 1;
}

"String" datatype in Java can hold both numbers and strings (as you asked). You can get user input using Scanner utility as below:
Scanner input = new Scanner();
userChoice = input.nextLine(); // if it is a string
//userChoice = input.nextInt(); // if it's integer choice
If your string is an integer then you can also parse it to get its integer value. For parsing:
int value = Integer.parseInt(userChoice);
Also for comparing String values you should use "equals" function rather than "==".
if(userChoice.equals("Heads")){...} //rather than if(userChoice == "Heads"){...}

Having imported java.util.Scanner, to get input from the user as a String, create a Scanner object that parameterizes System.in and assign userChoice the value of nextLine() invoked by the Scanner object:
Scanner input = new Scanner(System.in);
String userChoice = input.nextLine();
A few things about your code. The relational operator, ==, is used for comparing primitive data - not objects. Use string1.equals(string2) to see if two strings are equal.
Also, bob = (int) Math.floor(Math.random()*2); is really bob = (int)(Math.random() * 2);
because casting a double as an integer truncates the double to the highest integer less than or equal to it.

It might help you to get the ideas.
public static void main(String[] args) {
Random rd = new Random();
//Enter 1 0R 0
int bob = rd.nextInt(2);
String userChoice;
Scanner sc = new Scanner(System.in);
System.out.println("Please enter a number");
userChoice = sc.nextLine();
System.out.println("You entered " + userChoice + " and bob is " + bob);
int uc = Integer.parseInt(userChoice);
if (uc == bob) {
System.out.println("Hehe");
} else {
System.out.println("Sorry");
}
}

If statement skipping right to else after being called once?

I'm making a simple coin toss game, and I wrote several methods to call and make my main class short and simple. After the game is played once, the first If/Else statement to ask users for input is jumping right to the Else statement without prompting for input.
package cointoss;
import java.util.Random;
import java.util.Scanner;
public class Game {
int money;
int result;
int bet;
Random rn = new Random();
Scanner in = new Scanner(System.in);
String playerPick;
String aResult;
public void setMoney(int a)
{
money = a;
}
public int getMoney()
{
return money;
}
public void getBet()
{
System.out.println("How much would you like to bet?");
bet = in.nextInt();
do{
if(bet > money)
{
System.out.println("You cannot bet more than you have!");
System.out.println("You have bet " + (bet - money) + " too many coins.");
continue;
}
else
System.out.println("You have bet " + bet + " coins.");
}
while(bet > money);
}
public void getInput()
{
System.out.println("Pick Heads or Tails");
playerPick = in.nextLine();
playerPick.toLowerCase();
if(playerPick.contains("heads"))
playerPick ="heads";
else if(playerPick.contains("tails"))
playerPick ="tails";
else
System.out.println("Invalid Selection");
}
public void flipCoin()
{
result = rn.nextInt(2);
if(result == 0)
{
aResult = "heads";
}
else
aResult = "tails";
}
public void checkResult()
{
if(playerPick.equals(aResult))
{
System.out.println("You have won!");
money += bet;
System.out.println("You now have " + money + " coins");
}
else{
System.out.println("You have lost!");
money -= bet;
System.out.println("You now have " + money + " coins");
}
}
}
My Tester Class:
package cointoss;
public class GameTest {
public static void main(String[] args)
{
Game coinToss = new Game();
coinToss.setMoney(100);
while(coinToss.getMoney() > 0)
{
coinToss.getInput();
coinToss.getBet();
coinToss.flipCoin();
coinToss.checkResult();
}
}
}

The method toLowerCase() does not change the contents of the string; String is an immutable class in Java. The toLowerCase() method returns the result. You need to change
playerPick.toLowerCase();
to
playerPick = playerPick.toLowerCase();

Your problem is that you are not reinitializing "in" as a new Scanner every time you run the tester loop. The single scanner reads a line of input and accepts that as the full answer, without acknowledging that there could be further input.

The problem is that when the user enters a line, the input buffer will contain characters followed by a "newline" (end-of-line) character. When you use nextInt, the Scanner will find and skip over an integer. But it won't skip over the end-of-line. So when you next call nextLine in getInput(), it will then find what's left of the previous line, i.e. an empty string, and return that. Some things you'll need to do:
(1) In getBet, add in.nextLine() at the end of the method, to skip past the end-of-line. nextLine will return a string but you can ignore it. See also Scanner issue when using nextLine after nextXXX
(2) getInput needs to have a loop so that if the user enters an invalid input, you go back and ask him to enter a valid string. Otherwise, it will display "Invalid Selection" but then ask for a bet, which isn't what you want.
(3) See the other answers with regard to toLowerCase.

When you use
playerPick.toLowerCase();
It does nothing because the value is not being assigned to anything. In order to change a value of an object you must assign a value to it, as below:
playerPick = Pick.toLowerCase();
This assigns the value, rather than calling an empty method
Hope this helps :)