Question

It has no errors, but when I run it, it crashes. The portion of my code that I believe the problem is in is as follows:

    int h = (a * c);
    List<Integer> factors = new ArrayList<Integer>();
    for (int i = 1; i < Math.sqrt(h); i++) {
        if (h % i == 0)
            factors.add(i);
    }
    Integer result = null;
    for (int ii : factors) {
        if (b == ii + h / ii) {
            result = ii;
            // ax^2+hiix+iix+c
        }
        int hii = h / ii;
        int gcd1 = Euclid.getGcd(a, hii);
        int gcd2 = Euclid.getGcd(ii, c);
        String factored1 = ("(" + gcd1 + "x+" + gcd2 + ")");
        int fact21 = (a / gcd1);
        int fact22 = (hii / gcd1);
        String factored2 = ("(" + fact21 + "x+" + fact22 + ")");
        EditText tvfact1a = (EditText) findViewById(R.id.tvfact1);
        EditText tvfact2a = (EditText) findViewById(R.id.tvfact2);
        tvfact1a.setText(factored1);
        tvfact2a.setText(factored2);
    }

a and c are initialized earlier in the program. The Euclid class is as follows:

package boston.project;

public class Euclid {
    public static int getGcd(int a, int b) {
        while (b != 0) {
            if (a > b) {
                a -= b;
            } else {
                b -= a;
            }
        }
        return a;
    }
}

EDIT

LogCat

01-01 15:28:59.479: W/KeyCharacterMap(303): No keyboard for id 0
01-01 15:28:59.479: W/KeyCharacterMap(303): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
01-01 16:22:03.158: W/KeyCharacterMap(334): No keyboard for id 0
01-01 16:22:03.158: W/KeyCharacterMap(334): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
01-01 16:22:16.739: D/AndroidRuntime(334): Shutting down VM
01-01 16:22:16.739: W/dalvikvm(334): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
01-01 16:22:16.759: E/AndroidRuntime(334): FATAL EXCEPTION: main
01-01 16:22:16.759: E/AndroidRuntime(334): java.lang.ClassCastException: android.widget.TextView
01-01 16:22:16.759: E/AndroidRuntime(334): at boston.project.TheBostonProjectActivity$1.onClick(TheBostonProjectActivity.java:138)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.view.View.performClick(View.java:2408)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.view.View$PerformClick.run(View.java:8816)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.os.Handler.handleCallback(Handler.java:587)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.os.Handler.dispatchMessage(Handler.java:92)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.os.Looper.loop(Looper.java:123)
01-01 16:22:16.759: E/AndroidRuntime(334): at android.app.ActivityThread.main(ActivityThread.java:4627)
01-01 16:22:16.759: E/AndroidRuntime(334): at java.lang.reflect.Method.invokeNative(Native Method)
01-01 16:22:16.759: E/AndroidRuntime(334): at java.lang.reflect.Method.invoke(Method.java:521)
01-01 16:22:16.759: E/AndroidRuntime(334): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-01 16:22:16.759: E/AndroidRuntime(334): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-01 16:22:16.759: E/AndroidRuntime(334): at dalvik.system.NativeStart.main(Native Method)

Answer 1

I think the error occurs because you are using a TextView in your layout but try to cast it to a EditText in your code.
You should change

EditText tvfact1a = (EditText) findViewById(R.id.tvfact1);
EditText tvfact2a = (EditText) findViewById(R.id.tvfact2);

to

TextView tvfact1a = (TextView) findViewById(R.id.tvfact1);
TextView tvfact2a = (TextView) findViewById(R.id.tvfact2);