P3 finished

app/src/main/AndroidManifest.xml

@@ -1,7 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
-    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
+
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
@@ -12,6 +14,9 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Android101"
         tools:targetApi="31">
+        <activity
+            android:name=".Page4"
+            android:exported="false" />
         <activity
             android:name=".Page3"
             android:exported="false" />

app/src/main/java/uk/kagurach/android101/Kaculate.kt

@@ -14,8 +14,7 @@ fun Kaculate(src: String,ctx :Context) : String{
 
     var _curnum = ""
 
-    var _immediatePop = false
+    for (i in src.indices){
-    for (i in 0..<src.length){
         if (src[i] in '0'..'9' || src[i] == '.'){
             _curnum += src[i]
         }
@@ -27,27 +26,7 @@ fun Kaculate(src: String,ctx :Context) : String{
                 ToastHelper.ShowToast(e.toString(),ctx)
                 return src
             }
-
+             opStack += src[i]
-            if (_immediatePop){
-                try {
-                    val exp = numStack.last()
-                    numStack.dropLast(1)
-                    val num = numStack.last()
-                    numStack.dropLast(1)
-
-                    numStack += num.pow(exp)
-                    _immediatePop = false
-                }catch (e:Exception){
-                    ToastHelper.ShowToast(e.toString(),ctx)
-                    return src
-                }
-            }
-
-            if (src[i] == '^'){
-                _immediatePop = true
-            }else{
-                opStack += src[i]
-            }
         }
         else{
             ToastHelper.ShowToast("Unknown input char:" + src[i].toString(),ctx);
@@ -58,7 +37,6 @@ fun Kaculate(src: String,ctx :Context) : String{
     if (_curnum.isNotEmpty()){
         try {
             numStack += _curnum.toFloat()
-            _curnum = ""
         }catch (e:Exception){
             ToastHelper.ShowToast(e.toString(),ctx)
             return src
@@ -70,35 +48,80 @@ fun Kaculate(src: String,ctx :Context) : String{
         return src
     }
 
-    var intStackCurr = 0
+    // ^
-    for (i in 0..<opStack.size){
+    if ('^' in opStack){
-        if (opStack[i] == 'x'){
+        var intStackCurr = 0
+        for (i in opStack.indices){
+            if (opStack[i]!='^'){
+                intStackCurr ++
+                continue
+            }
+
             val a = numStack[intStackCurr]
             val b = numStack[intStackCurr+1]
-            numStack[intStackCurr] = a*b
+            numStack[intStackCurr] = a.pow(b)
-            numStack.drop(intStackCurr+1)
+            numStack = dropAtIdx(numStack,intStackCurr+1)
-            opStack.drop(i)
-        }else if (opStack[i] == '/'){
-            val a = numStack[intStackCurr]
-            val b = numStack[intStackCurr+1]
-            numStack[intStackCurr] = a/b
-            numStack.drop(intStackCurr+1)
-            opStack.drop(i)
-        }else{
-            intStackCurr ++
         }
     }
-    if (opStack.size!=0) {
+    // x and /
+    var intStackCurr = 0
+    for (i in opStack.indices){
+        if (opStack[i]!='x'&&opStack[i]!='/'){
+            intStackCurr ++
+            continue
+        }
+
+        val a = numStack[intStackCurr]
+        val b = numStack[intStackCurr+1]
+
+        if (opStack[i] == 'x'){
+            numStack[intStackCurr] = a*b
+        }else{
+            numStack[intStackCurr] = a/b
+        }
+
+        numStack = dropAtIdx(numStack,intStackCurr+1)
+    }
+
+    // + and -
+    if (opStack.isNotEmpty()) {
         for (i in opStack) {
             if (i == '+') {
                 numStack[0] += numStack[1]
-                numStack.drop(1)
+                numStack = dropAtIdx(numStack,1)
-            } else {
+            } else if (i=='-') {
                 numStack[0] -= numStack[1]
-                numStack.drop(1)
+                numStack = dropAtIdx(numStack,1)
             }
         }
     }
 
     return numStack[0].toString()
 }
+
+private fun dropAtIdx(array: FloatArray, idx:Int): FloatArray{
+    if (idx>array.size){
+        throw IndexOutOfBoundsException()
+    }
+
+    var newArray = floatArrayOf()
+    for (i in array.indices){
+        if (i!=idx){
+            newArray += array[i]
+        }
+    }
+    return newArray
+}
+private fun dropAtIdx(array: CharArray, idx:Int): CharArray{
+    if (idx>array.size){
+        throw IndexOutOfBoundsException()
+    }
+
+    var newArray = charArrayOf()
+    for (i in array.indices){
+        if (i!=idx){
+            newArray += array[i]
+        }
+    }
+    return newArray
+}

app/src/main/java/uk/kagurach/android101/Page3.java

@@ -2,12 +2,14 @@ package uk.kagurach.android101;
 
 import static uk.kagurach.android101.KaculateKt.Kaculate;
 
+import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Button;
 import android.widget.TextView;
 
 import androidx.activity.EdgeToEdge;
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
@@ -35,14 +37,20 @@ public class Page3 extends AppCompatActivity {
         findViewById(R.id.P3_8).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3_9).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3BK).setOnClickListener(new CalculateOnClickListener());
+
         findViewById(R.id.P3X).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3Plus).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3Minus).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3Div).setOnClickListener(new CalculateOnClickListener());
+        findViewById(R.id.P3ChengFang).setOnClickListener(new CalculateOnClickListener());
+
         findViewById(R.id.P3Dot).setOnClickListener(new CalculateOnClickListener());
         findViewById(R.id.P3CE).setOnClickListener(new CalculateOnClickListener());
-        findViewById(R.id.P3ChengFang).setOnClickListener(new CalculateOnClickListener());
+
         findViewById(R.id.P3EqualButton).setOnClickListener(new CalculateOnClickListener());
+
+        findViewById(R.id.P3Nextpage).setOnClickListener(new PageButtonHandler());
+        findViewById(R.id.P3Nextpage).setOnLongClickListener(new LongClickHandler());
     }
 
 
@@ -53,28 +61,124 @@ public class Page3 extends AppCompatActivity {
             TextView tv = findViewById(R.id.P3CalcResult);
             String s = tv.getText().toString();
             String o = ((Button)v).getText().toString();
+            Button dot = findViewById(R.id.P3Dot);
             switch (o){
                 case "退格":
                     if (!s.isEmpty()){
-                        s = s.substring(0,s.length()-1);
+                        if (s.length()==1){
+                            s = "";
+                            dot.setEnabled(true);
+                            setOpButton(true);
+                        }else {
+                            s = s.substring(0, s.length() - 1);
+                            dot.setEnabled(!isNumberWithDot(s));
+                            setOpButton(s.substring(s.length()-1).matches("\\d|\\."));
+                        }
                     }
                     break;
                 case "CE":
                     s = "";
+                    dot.setEnabled(true);
                     break;
                 case "=":
                     calc();
+                    s = tv.getText().toString();
+                    if (!s.contains(".")){
+                        dot.setEnabled(true);
+                    }
+                    setOpButton(true);
+
                     return;
+                case ".":
+                    dot.setEnabled(false);
+                    s+='.';
+                    break;
                 default:
                     s += o;
+                    if (o.matches("\\d")) {  // If inputted a number
+                        setOpButton(true);
+                    }else{ // Else an operator
+                        dot.setEnabled(true);
+                        setOpButton(false);
+                    }
             }
             tv.setText(s);
         }
     }
 
+    private void setOpButton(boolean state){
+        findViewById(R.id.P3X).setEnabled(state);
+        findViewById(R.id.P3Plus).setEnabled(state);
+        findViewById(R.id.P3Minus).setEnabled(state);
+        findViewById(R.id.P3Div).setEnabled(state);
+        findViewById(R.id.P3ChengFang).setEnabled(state);
+    }
+
+    private boolean isNumberWithDot(@NonNull String s){
+        if (!s.contains(".")){
+            return false;
+        }
+        boolean hasDot = false;
+        for (int i = s.length()-1; i >= 0; i--) {
+            char c = s.charAt(i);
+            if (c=='+'||c=='-'||c=='x'||c=='/'||c=='^'){
+                return hasDot;
+            }else if (c=='.'){
+                hasDot = true;
+            }
+        }
+        return hasDot;
+    }
+
     private void calc(){
         TextView textView = findViewById(R.id.P3CalcResult);
         String result = Kaculate(textView.getText().toString(),this);
+
+        if (result.contains(".")) { // In case of Infinity or NaN as a result
+            int i = 0;
+            while (result.charAt(i) != '.') {
+                i++;
+            }
+            int j = i;
+            boolean notZero = false;
+            for (i++; i < result.length(); i++) {
+                if (result.charAt(i) != '0') {
+                    notZero = true;
+                }
+            }
+
+            if (!notZero) {
+                result = result.substring(0, j);
+            }
+        }
+
         textView.setText(result);
     }
+
+    public void goNext() {
+        Intent myIntent = new Intent(this, Page4.class);
+        startActivity(myIntent);
+    }
+
+    public void goPrev() {
+        Intent myIntent = new Intent(this, MainActivity2.class);
+        startActivity(myIntent);
+    }
+    final class PageButtonHandler implements View.OnClickListener
+    {
+        @Override
+        public void onClick(View v){
+            goNext();
+        }
+    }
+
+    final class LongClickHandler implements View.OnLongClickListener
+    {
+        @Override
+        public boolean onLongClick(View v){
+            goPrev();
+            return false;
+        }
+    }
+
 }

app/src/main/java/uk/kagurach/android101/Page4.java

@@ -0,0 +1,24 @@
+package uk.kagurach.android101;
+
+import android.os.Bundle;
+
+import androidx.activity.EdgeToEdge;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.graphics.Insets;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowInsetsCompat;
+
+public class Page4 extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        EdgeToEdge.enable(this);
+        setContentView(R.layout.activity_page4);
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
+            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
+            return insets;
+        });
+    }
+}

app/src/main/res/layout/activity_page3.xml

@@ -6,196 +6,192 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".Page3">
-
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:orientation="vertical">
+        android:orientation="vertical"
+        >
         <View
             android:id="@+id/view"
             android:layout_width="match_parent"
             android:layout_height="35dp" />
-
         <TextView
             android:id="@+id/P3CalcName"
             android:layout_width="match_parent"
             android:layout_height="50dp"
             android:text="@string/kaculate"
             android:textSize="40sp"/>
-
         <TextView
             android:id="@+id/P3CalcResult"
             android:layout_width="match_parent"
             android:layout_height="400dp"
+            android:textSize="25sp"
             android:text="" />
-
+        <LinearLayout
-        <GridLayout
             android:layout_width="match_parent"
-            android:layout_height="match_parent"
+            android:layout_height="0dp"
-            android:columnCount="4"
+            android:layout_weight="1"
-            android:rowCount="5">
+            android:orientation="vertical">
-
+            <LinearLayout
-
+                android:layout_width="match_parent"
-            <Button
+                android:layout_height="0dp"
-                android:id="@+id/P3CE"
+                android:layout_weight="1"
-                android:layout_width="wrap_content"
+                android:orientation="horizontal">
-                android:layout_height="wrap_content"
+                <Button
-                android:layout_row="0"
+                    android:id="@+id/P3CE"
-                android:layout_column="0"
+                    android:layout_weight="1"
-                android:text="CE" />
+                    android:layout_width="wrap_content"
-
+                    android:layout_height="match_parent"
-            <Button
+                    android:text="CE" />
-                android:id="@+id/P3Div"
+                <Button
-                android:layout_width="wrap_content"
+                    android:id="@+id/P3Div"
-                android:layout_height="wrap_content"
+                    android:layout_weight="1"
-                android:layout_row="0"
+                    android:layout_width="wrap_content"
-                android:layout_column="1"
+                    android:layout_height="match_parent"
-                android:text="/" />
+                    android:text="/" />
-
+                <Button
-            <Button
+                    android:id="@+id/P3X"
-                android:id="@+id/P3X"
+                    android:layout_weight="1"
-                android:layout_width="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
+                    android:layout_height="match_parent"
-                android:layout_row="0"
+                    android:text="x" />
-                android:layout_column="2"
+                <Button
-                android:text="x" />
+                    android:id="@+id/P3Nextpage"
-
+                    android:layout_weight="1"
-            <Button
+                    android:layout_width="wrap_content"
-                android:id="@+id/P3Nextpage"
+                    android:layout_height="match_parent"
-                android:layout_width="wrap_content"
+                    android:text="@string/next_page" />
-                android:layout_height="wrap_content"
+            </LinearLayout>
-                android:layout_row="0"
+            <LinearLayout
-                android:layout_column="3"
+                android:layout_width="match_parent"
-                android:text="@string/next_page" />
+                android:layout_height="0dp"
-
+                android:layout_weight="1"
-            <Button
+                android:orientation="horizontal">
-                android:id="@+id/P3_7"
+                <Button
-                android:layout_width="wrap_content"
+                    android:id="@+id/P3_7"
-                android:layout_height="wrap_content"
+                    android:layout_weight="1"
-                android:layout_row="1"
+                    android:layout_width="wrap_content"
-                android:layout_column="0"
+                    android:layout_height="match_parent"
-                android:text="7" />
+                    android:backgroundTint="@color/tfb"
-
+                    android:text="7" />
-            <Button
+                <Button
-                android:id="@+id/P3_8"
+                    android:id="@+id/P3_8"
-                android:layout_width="wrap_content"
+                    android:layout_weight="1"
-                android:layout_height="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_row="1"
+                    android:layout_height="match_parent"
-                android:layout_column="1"
+                    android:backgroundTint="@color/tfb"
-                android:text="8" />
+                    android:text="8" />
-
+                <Button
-            <Button
+                    android:id="@+id/P3_9"
-                android:id="@+id/P3_9"
+                    android:layout_weight="1"
-                android:layout_width="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
+                    android:layout_height="match_parent"
-                android:layout_row="1"
+                    android:backgroundTint="@color/tfb"
-                android:layout_column="2"
+                    android:text="9" />
-                android:text="9" />
+                <Button
-
+                    android:id="@+id/P3Plus"
-            <Button
+                    android:layout_weight="1"
-                android:id="@+id/P3Plus"
+                    android:layout_width="wrap_content"
-                android:layout_width="wrap_content"
+                    android:layout_height="match_parent"
-                android:layout_height="wrap_content"
+                    android:text="+" />
-                android:layout_row="1"
+            </LinearLayout>
-                android:layout_column="3"
+            <LinearLayout
-                android:text="+" />
+                android:layout_width="match_parent"
-
+                android:layout_height="0dp"
-            <Button
+                android:layout_weight="1"
-                android:id="@+id/P3_4"
+                android:orientation="horizontal">
-                android:layout_width="wrap_content"
+                <Button
-                android:layout_height="wrap_content"
+                    android:id="@+id/P3_4"
-                android:layout_row="2"
+                    android:layout_weight="1"
-                android:layout_column="0"
+                    android:layout_width="wrap_content"
-                android:text="4" />
+                    android:layout_height="match_parent"
-
+                    android:backgroundTint="@color/tfb"
-            <Button
+                    android:text="4" />
-                android:id="@+id/P3_5"
+                <Button
-                android:layout_width="wrap_content"
+                    android:id="@+id/P3_5"
-                android:layout_height="wrap_content"
+                    android:layout_weight="1"
-                android:layout_row="2"
+                    android:layout_width="wrap_content"
-                android:layout_column="1"
+                    android:layout_height="match_parent"
-                android:text="5" />
+                    android:backgroundTint="@color/tfb"
-
+                    android:text="5" />
-            <Button
+                <Button
-                android:id="@+id/P3_6"
+                    android:id="@+id/P3_6"
-                android:layout_width="wrap_content"
+                    android:layout_weight="1"
-                android:layout_height="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_row="2"
+                    android:layout_height="match_parent"
-                android:layout_column="2"
+                    android:backgroundTint="@color/tfb"
-                android:text="6" />
+                    android:text="6" />
-
+                <Button
-            <Button
+                    android:id="@+id/P3Minus"
-                android:id="@+id/P3Minus"
+                    android:layout_weight="1"
-                android:layout_width="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
+                    android:layout_height="match_parent"
-                android:layout_row="2"
+                    android:text="-" />
-                android:layout_column="3"
+            </LinearLayout>
-                android:text="-" />
+            <LinearLayout
-
+                android:layout_width="match_parent"
-            <Button
+                android:layout_height="0dp"
-                android:id="@+id/P3_1"
+                android:layout_weight="1"
-                android:layout_width="wrap_content"
+                android:orientation="horizontal">
-                android:layout_height="wrap_content"
+                <Button
-                android:layout_row="3"
+                    android:id="@+id/P3_1"
-                android:layout_column="0"
+                    android:layout_weight="1"
-                android:text="1" />
+                    android:layout_width="wrap_content"
-
+                    android:layout_height="match_parent"
-            <Button
+                    android:backgroundTint="@color/tfb"
-                android:id="@+id/P3_2"
+                    android:text="1" />
-                android:layout_width="wrap_content"
+                <Button
-                android:layout_height="wrap_content"
+                    android:id="@+id/P3_2"
-                android:layout_row="3"
+                    android:layout_weight="1"
-                android:layout_column="1"
+                    android:layout_width="wrap_content"
-                android:text="2" />
+                    android:layout_height="match_parent"
-
+                    android:backgroundTint="@color/tfb"
-            <Button
+                    android:text="2" />
-                android:id="@+id/P3_3"
+                <Button
-                android:layout_width="wrap_content"
+                    android:id="@+id/P3_3"
-                android:layout_height="wrap_content"
+                    android:layout_weight="1"
-                android:layout_row="3"
+                    android:layout_width="wrap_content"
-                android:layout_column="2"
+                    android:layout_height="match_parent"
-                android:text="3" />
+                    android:backgroundTint="@color/tfb"
-
+                    android:text="3" />
-            <Button
+                <Button
-                android:id="@+id/P3ChengFang"
+                    android:id="@+id/P3ChengFang"
-                android:layout_width="wrap_content"
+                    android:layout_weight="1"
-                android:layout_height="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_row="3"
+                    android:layout_height="match_parent"
-                android:layout_column="3"
+                    android:text="^" />
-                android:text="^" />
+            </LinearLayout>
-
+            <LinearLayout
-            <Button
+                android:layout_width="match_parent"
-                android:id="@+id/P3BK"
+                android:layout_height="0dp"
-                android:layout_width="wrap_content"
+                android:layout_weight="1"
-                android:layout_height="wrap_content"
+                android:orientation="horizontal">
-                android:layout_row="4"
+                <Button
-                android:layout_column="0"
+                    android:id="@+id/P3BK"
-                android:text="@string/Backspace" />
+                    android:layout_weight="1"
-
+                    android:layout_width="wrap_content"
-            <Button
+                    android:layout_height="match_parent"
-                android:id="@+id/P3_0"
+                    android:text="@string/Backspace" />
-                android:layout_width="wrap_content"
+                <Button
-                android:layout_height="wrap_content"
+                    android:id="@+id/P3_0"
-                android:layout_row="4"
+                    android:layout_weight="1"
-                android:layout_column="1"
+                    android:layout_width="wrap_content"
-                android:text="0" />
+                    android:layout_height="match_parent"
-
+                    android:backgroundTint="@color/tfb"
-            <Button
+                    android:text="0" />
-                android:id="@+id/P3Dot"
+                <Button
-                android:layout_width="wrap_content"
+                    android:id="@+id/P3Dot"
-                android:layout_height="wrap_content"
+                    android:layout_weight="1"
-                android:layout_row="4"
+                    android:layout_width="wrap_content"
-                android:layout_column="2"
+                    android:layout_height="match_parent"
-                android:text="." />
+                    android:text="." />
-
+                <Button
-            <Button
+                    android:id="@+id/P3EqualButton"
-                android:id="@+id/P3EqualButton"
+                    android:layout_weight="1"
-                android:layout_width="wrap_content"
+                    android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
+                    android:layout_height="match_parent"
-                android:layout_row="4"
+                    android:text="=" />
-                android:layout_column="3"
+            </LinearLayout>
-                android:text="=" />
+        </LinearLayout>
-        </GridLayout>
-
     </LinearLayout>
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_page4.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".Page4">
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/values/colors.xml

@@ -7,4 +7,7 @@
     <color name="teal_700">#FF018786</color>
     <color name="black">#FF000000</color>
     <color name="white">#FFFFFFFF</color>
+
+    <color name="tfb">#5BCEFA</color>
+    <color name="tfp">#F5A9B8</color>
 </resources>

app/src/main/res/values/strings.xml

@@ -7,6 +7,6 @@
     <string name="set_color">设置颜色</string>
     <string name="set">设置</string>
     <string name="setText">设置文本</string>
-    <string name="kaculate">Kaculate</string>
+    <string name="kaculate">弱智计算器</string>
     <string name="Backspace">退格</string>
 </resources>