Add Java assignments to the repository

.gitignore: The build files, files left by editors like *~ and the PDF
documents for the assignments are to be ignored for the purposes of
version control.

README.rst: Rewrite, with one line description in Chinese.

java/alist.txt: List of assignments, sorted in the order of the list of
assignments, with the ones with completed documentation marked with `#`.

java/buildall: Script that will build all of the assignments into one
PDF file; to be rehauled for the final document.

code/*.java: The Java source code for the assignments.

dbld: Script that builds a PDF document for a single assignment.

index.typ: The list of assignments, subject to update for further
refinement and inclusion of yet more assignments.

jbld: Script that compiles code for a single Java assignment.

output/*.typ: Typst file containing the output (sessions) obtained from
running the individual Java assignments.

state.sql: Future alternative to `alist.txt`, under development.

template.typ: The Typst template used across all of assignment,
containing common code for the uniform styling, such as page border.

text/*.typ: Typst file documenting each Java assignment.

vendor/Java.sublime-syntax: Updated Sublime Text syntax file for Java,
used for newer syntax features, such as `var`, not yet available in
syntaxes shipped with Typst.

vendor/gr.tmTheme: A grayscale TextMate theme to be used for code in the
documents generated by Typst suitable for black and white printing.

wltd: Difference between the files in `code/` and `text/`, and `code/`
and `output`; need to be rewritten along with `state.sql`.

1 files changed, 72 insertions, 0 deletions

diff --git a/java/code/FindNumberInArray.java b/java/code/FindNumberInArray.java
new file mode 100644
index 0000000..2bf7f1a
--- /dev/null
+++ b/java/code/FindNumberInArray.java
@@ -0,0 +1,72 @@
+import java.util.Scanner;
+import java.util.InputMismatchException;
+
+class Number {
+    private double value;
+    Number(double n) {
+        value = n;
+    }
+    double valueOf() {
+        return value;
+    }
+    @Override
+    public boolean equals(Object o) {
+        if (o instanceof Number) {
+            return value == ((Number)o).valueOf();
+        }
+        return false;
+    } 
+}
+
+class NumberArray {
+    Number[] array;
+    NumberArray(double arr[]) {
+        array = new Number[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            array[i] = new Number(arr[i]);
+        }
+    }
+    int find(Number n) {
+        for (int i = 0; i < array.length; i++) {
+            if (array[i].equals(n)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+    void display() {
+        System.out.print("An array of numbers with " + array.length + " elements:");
+        for (int i = 0; i < array.length; i++) {
+            System.out.print(" " + array[i].valueOf());
+        }
+        System.out.println();
+    }
+}
+
+class FindNumberInArray {
+    public static void main(String args[]) {
+        try {
+            var sc = new Scanner(System.in);
+            System.out.print("Enter length: ");
+            var length = sc.nextInt();
+            var arr = new double[length];
+            System.out.print("Enter array elements: ");
+            for (int i = 0; i < length; i++) {
+                arr[i] = sc.nextDouble();
+            }
+            var narr = new NumberArray(arr);
+            System.out.print("Given: ");
+            narr.display();
+            System.out.print("Enter element to find in array: ");
+            var num = new Number(sc.nextDouble());
+            var pos = narr.find(num);
+            if (pos == -1) {
+                System.out.println("Could not find the number " + num.valueOf() + " in the array.");
+                return;
+            }
+            System.out.println("The number " + num.valueOf() + " was found in the array at position " + (pos + 1) + ".");
+        } catch (InputMismatchException e) {
+            System.err.println("Invalid number given as input");
+        }
+    }
+}