java

[Solved] I’m writing my first ever java program and it’s not compiling for a certain reason [duplicate]

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basically the compiler tells you whats wrong. It says, “class main is public, should be declared in a file named main.java”. Java has a naming rule, that a class inside a java file needs to match that file name. Example 1: Filename -> File.java inside that file: public class Main{ … does violate that rule … Read more

[Solved] In Pair.of() : Can you change the name of(S first, T second)? [closed]

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Solution for Jackson: Declare serializer for specific class Pair public static class PairSerializer extends StdSerializer<Pair> { public PairSerializer() { this(null); } public PairSerializer(Class<Pair> t) { super(t); } @Override public void serialize(Pair value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException { jgen.writeStartObject(); jgen.writeObjectField(“a”, value.getFirst()); // “a” is replacement for “first” jgen.writeObjectField(“b”, value.getSecond()); // “b” is replacement … Read more

[Solved] To store gps location in firebase real time database

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You can send the location to Firebase by using the Firebase Database and DatabaseReference classes. First you have to make sure that you have these SDK’s in build.gradle: implementation ‘com.google.firebase:firebase-storage:16.0.4’ implementation ‘com.google.firebase:firebase-database:16.0.4’ Also, make sure that you have set up your Realtime Database in the Firebase Console. It would be best if you choose the … Read more

[Solved] When assigning a value Java gives the error ‘java: expected’, Why? [duplicate]

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Your’re probably not using it in a method. Place it in a method as shown below : public static void main(String[] args) { char aCharacter=”A”; aCharacter=”\u0041″; } This is because assignments are statements and statements are allowed only inside blocks of code. 0 solved When assigning a value Java gives the error ‘java: expected’, Why? … Read more

[Solved] need to determine the positive, negative and zero numbers in program and add all the positive and negative numbers separately [closed]

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Is the problem that you want to run the loop 10 times? You’ve got a count variable that you are not otherwise using. The loop should look something like: int count=0; while (count != 10) { … ++count; } Conventionally a for loop is used for this (if allowed): for (int count=0; count<10; ++count) { … Read more

[Solved] Can I call a .java file from a .html file with href or something else without using javascript in-between [closed]

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Updated from OP comment: Thank you very much for your reply and let me correct the question can I call a function which is written in java directly from a html. – JAVA Coder Nov 5 at 9:08 Still the same answer. Methods or functions, terminology aside. What you’re proposing is like trying to power … Read more

[Solved] How to check if there are 2 upper case letters, 3 lower case letters, and 1 number in JAVA

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This looks like a homework question so I won’t solve it directly. However here are some steps you could take: Create a method to validate the input (public static boolean isValid(String str)) Convert the String to a character Array. (There’s a method for that!) Iterate over the letters and keep track of how many upper … Read more

[Solved] why this lambda expression do not work when in statement ,but work in method?

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In your second code version: Map<Object, Boolean> seen = new ConcurrentHashMap<>(); The map Map<> seen is initialized for every element x, therefore your filter always return true which will let all elements passthrough. Move the Map<> seen declaration to outside the lambda will correct your usage. In the first code version, the Map<> seen is … Read more

[Solved] why is it showing error . Like I thought the third loop will end and it will enter the first loop but didn’t else showed an exception

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just replace the condition of the there loops with 26. Now the exception index out of bound will not occur public class SuggestingAppNames { public static void main(String[] args) { System.out.println(“the possible outcomes are”); String a = “A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z”; String d[] = a.split(“,”); String b = “A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z”; String e[] = b.split(“,”); String c = “A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z”; String … Read more

[Solved] How do I show a result from Random in a textview?

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You have to add a TextView to display the result. Step 1. Adding ID to TextView, in the XML file. <TextView android:id=”@+id/myId” android:layout_width=”wrap_content” android:layout_height=”wrap_content” …. /> Step 2. Finding TextView using ID, under onCreate method: @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); TextView myTextView = (TextView) findViewById(R.id.myId); } Step 3. Set the text with … Read more