Question

我试图让操作员在切换方向时进行更改。例如，如果用户点击9后跟X（代表相乘），然后更改方向，则后跟3和=。我希望它显示18，但我得到0。

这是我的MainActivity：

public class MainActivity extends Activity implements View.OnClickListener{

private static String TAG = "MainActivity";
private EditText mCalculatorDisplay;
private Boolean userIsInTheMiddleOfTypingANumber = false;
private CalculatorBrain mCalculatorBrain;
private static final String DIGITS = "0123456789.";

DecimalFormat df = new DecimalFormat("@###########");

@Override
protected void onCreate(Bundle savedInstanceState) {
    if (BuildConfig.DEBUG) { Log.d(TAG, "onCreate called");}

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mCalculatorBrain = new CalculatorBrain();
    mCalculatorDisplay = (EditText) findViewById(R.id.display);

    df.setMinimumFractionDigits(0);
    df.setMinimumIntegerDigits(1);
    df.setMaximumIntegerDigits(8);

    findViewById(R.id.Button_Zero).setOnClickListener(this);
    findViewById(R.id.Button_One).setOnClickListener(this);
    findViewById(R.id.Button_Two).setOnClickListener(this);
    findViewById(R.id.Button_Three).setOnClickListener(this);
    findViewById(R.id.Button_Four).setOnClickListener(this);
    findViewById(R.id.Button_Five).setOnClickListener(this);
    findViewById(R.id.Button_Six).setOnClickListener(this);
    findViewById(R.id.Button_Seven).setOnClickListener(this);
    findViewById(R.id.Button_Eight).setOnClickListener(this);
    findViewById(R.id.Button_Nine).setOnClickListener(this);
    findViewById(R.id.Button_Add).setOnClickListener(this);
    findViewById(R.id.Button_Substract).setOnClickListener(this);
    findViewById(R.id.Button_Multiply).setOnClickListener(this);
    findViewById(R.id.Button_Divide).setOnClickListener(this);
    findViewById(R.id.Button_Dot).setOnClickListener(this);
    findViewById(R.id.Button_Sum).setOnClickListener(this);
    findViewById(R.id.Button_Clear).setOnClickListener(this);
    findViewById(R.id.Button_MemoryRecall).setOnClickListener(this);
    findViewById(R.id.Button_MemoryAdd).setOnClickListener(this);
    findViewById(R.id.Button_MemoryClear).setOnClickListener(this);

    // The following buttons only exist in layout-land (Landscape mode) and require extra attention.
    // The messier option is to place the buttons in the regular layout too and set android:visibility="invisible".
    if (findViewById(R.id.Button_SquareRoot) != null) {
        findViewById(R.id.Button_SquareRoot).setOnClickListener(this);
    }
    if (findViewById(R.id.Button_Squared) != null) {
        findViewById(R.id.Button_Squared).setOnClickListener(this);
    }
    if (findViewById(R.id.Button_Invert) != null) {
        findViewById(R.id.Button_Invert).setOnClickListener(this);
    }
    if (findViewById(R.id.Button_Sin) != null) {
        findViewById(R.id.Button_Sin).setOnClickListener(this);
    }
    if (findViewById(R.id.Button_Cos) != null) {
        findViewById(R.id.Button_Cos).setOnClickListener(this);
    }
    if (findViewById(R.id.Button_Tan) != null) {
        findViewById(R.id.Button_Tan).setOnClickListener(this);
    }
    if(findViewById(R.id.Button_Toggle) != null){
        findViewById(R.id.Button_Toggle).setOnClickListener(this);
    }

}

@Override
public void onClick(View v) {

    String buttonPressed = ((Button) v).getText().toString();

    if (DIGITS.contains(buttonPressed)) {

        // digit was pressed
        if (userIsInTheMiddleOfTypingANumber) {

                if (buttonPressed.equals(".") && mCalculatorDisplay.getText().toString().contains(".")) {
                // ERROR PREVENTION
                // Eliminate entering multiple decimals
            } else {
                mCalculatorDisplay.append(buttonPressed);
            }

        } else {

            if (buttonPressed.equals(".")) {
                // ERROR PREVENTION
                // This will avoid error if only the decimal is hit before an operator, by placing a leading zero
                // before the decimal
                mCalculatorDisplay.setText(0 + buttonPressed);
            } else {
                mCalculatorDisplay.setText(buttonPressed);
            }

            userIsInTheMiddleOfTypingANumber = true;
        }

    } else {
        // operation was pressed
        if (BuildConfig.DEBUG) { Log.d(TAG, "operation pressed");}
        if (userIsInTheMiddleOfTypingANumber) {

            mCalculatorBrain.setOperand(Double.parseDouble(mCalculatorDisplay.getText().toString()));
            userIsInTheMiddleOfTypingANumber = false;
        }

        mCalculatorBrain.performOperation(buttonPressed);
        mCalculatorDisplay.setText(df.format(mCalculatorBrain.getResult()));

    }

}

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    // Save variables on screen orientation change
    outState.putDouble("OPERAND", mCalculatorBrain.getResult());
    outState.putDouble("MEMORY", mCalculatorBrain.getMemory());
    if (BuildConfig.DEBUG) { Log.d(TAG, "onSaveInstanceState called");}
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // Restore variables on screen orientation change
    mCalculatorBrain.setOperand(savedInstanceState.getDouble("OPERAND"));
    mCalculatorBrain.setMemory(savedInstanceState.getDouble("MEMORY"));
    mCalculatorDisplay.setText(df.format(mCalculatorBrain.getResult()));
    if (BuildConfig.DEBUG) { Log.d(TAG, "onRestoreInstanceState called");}
}



 }

这是我的CalculatorBrain：

public class CalculatorBrain {
// 3 + 6 = 9
// 3 & 6 are called the operand.
// The + is called the operator.
private static String TAG = "CalculatorBrain";
// 9 is the result of the operation.
private double mOperand;
private double mWaitingOperand;
private String mWaitingOperator;
private double mCalculatorMemory;

// operator types
public static final String ADD = "+";
public static final String SUBTRACT = "-";
public static final String MULTIPLY = "x";
public static final String DIVIDE = "÷";
public static final String CLEAR = "DEL" ;
public static final String CLEARMEMORY = "MC";
public static final String ADDTOMEMORY = "M+";
public static final String RECALLMEMORY = "MR";
public static final String SQUAREROOT = "√";
public static final String SQUARED = "x²";
public static final String INVERT = "1/x";
public static final String TOGGLESIGN = "+/-";
public static final String SINE = "sin";
public static final String COSINE = "cos";
public static final String TANGENT = "tan";

// public static final String EQUALS = "=";

// constructor
public CalculatorBrain() {
    // initialize variables upon start
    mOperand = 0;
    mWaitingOperand = 0;
    mWaitingOperator = "";
    mCalculatorMemory = 0;
}

public void setOperand(double operand) {
    if(BuildConfig.DEBUG){Log.d(TAG, "setoperand value" + Double.toString(operand));}
    mOperand = operand;
    if (BuildConfig.DEBUG) { Log.d(TAG, "setOperand called");}
}

public double getResult() {
    if (BuildConfig.DEBUG) { Log.d(TAG, "getResult called");}
    return mOperand;

}

// used on screen orientation change
public void setMemory(double calculatorMemory) {
    if (BuildConfig.DEBUG) { Log.d(TAG, "setMemory called");}
    mCalculatorMemory = calculatorMemory;
}

// used on screen orientation change
public double getMemory() {
    if (BuildConfig.DEBUG) { Log.d(TAG, "getMemory called");}return mCalculatorMemory;
}


public String toString() {
    return Double.toString(mOperand);
}

protected double performOperation(String operator) {

    switch (operator) {
        case CLEAR:
            mOperand = 0;
            mWaitingOperator = "";
            mWaitingOperand = 0;
            break;
        case CLEARMEMORY:
            mCalculatorMemory = 0;
            break;
        case ADDTOMEMORY:
            mCalculatorMemory = mCalculatorMemory + mOperand;
            break;
        case RECALLMEMORY:
`enter code here`            mOperand = mCalculatorMemory;
            break;
        case SQUAREROOT:
            mOperand = Math.sqrt(mOperand);
            break;
        case SQUARED:
            mOperand = mOperand * mOperand;
            break;
        case INVERT:
            if (mOperand != 0) {
                mOperand = 1 / mOperand;
            } else {
                mOperand = 0;
            }
            break;
        case TOGGLESIGN:
            mOperand = -mOperand;
            break;
        case SINE:
            mOperand = Math.sin(Math.toRadians(mOperand));
            break;
        case COSINE:
            mOperand = Math.cos(Math.toRadians(mOperand));
            break;
        case TANGENT:
            mOperand = Math.tan(Math.toRadians(mOperand));
            break;
        default:
            performWaitingOperation();
            mWaitingOperand = mOperand;
            mWaitingOperator = operator;
            break;

    }
    return mOperand;
}

protected void performWaitingOperation() {
    if (BuildConfig.DEBUG) { Log.d(TAG, "performWaitingOperation called");}
    switch (mWaitingOperator){
        case ADD:
            mOperand = mWaitingOperand + mOperand;
            break;
        case MULTIPLY:
            mOperand = mWaitingOperand * mOperand;
            break;
        case SUBTRACT:
            mOperand = mWaitingOperand - mOperand;
            break;
        case DIVIDE:
            mOperand = mWaitingOperand / mOperand;
            break;
        }
    }
}

提前致谢！

Answer 1

使用以下

更改方法onSaveInstanceState

   super.onSaveInstanceState(outState);

应该在最后一次调用

@Override
protected void onSaveInstanceState(Bundle outState) {
   // Save variables on screen orientation change
   outState.putDouble("OPERAND", mCalculatorBrain.getResult());
   outState.putDouble("MEMORY", mCalculatorBrain.getMemory());
   if (BuildConfig.DEBUG) { Log.d(TAG, "onSaveInstanceState called");}
   super.onSaveInstanceState(outState);

}

Answer 2

这种情况正在发生，因为当您的活动更改其方向时它会重新启动。在清单文件中添加此内容

android:configChanges="orientation|screenSize|keyboardHidden"

这将阻止它重新启动。

保存操作员的方向更改

2 个答案: