package com.deitel.calculator;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
double input1 = 0, input2 = 0d ,count=0;
Button btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn_dot, btn_equal, btn_subtract, btn_multi, btn_add, btn_devision, btn_clear, btn_back;
TextView text_result;
boolean Addition, Subtraction, Multiplication, Devision, decimal;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn0 = findViewById(R.id.btn0);
btn1 = findViewById(R.id.btn1);
btn2 = findViewById(R.id.btn2);
btn3 = findViewById(R.id.btn3);
btn4 = findViewById(R.id.btn4);
btn5 = findViewById(R.id.btn5);
btn6 = findViewById(R.id.btn6);
btn7 = findViewById(R.id.btn7);
btn8 = findViewById(R.id.btn8);
btn9 = findViewById(R.id.btn9);
btn_dot = findViewById(R.id.btn_dot);
btn_equal = findViewById(R.id.btn_equal);
btn_add = findViewById(R.id.btn_add);
btn_subtract = findViewById(R.id.btn_subtract);
btn_multi = findViewById(R.id.btn_multi);
btn_devision = findViewById(R.id.btn_devision);
btn_clear = findViewById(R.id.btn_clear);
btn_back = findViewById(R.id.btn_back);
text_result = findViewById(R.id.text_result);
btn0.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "0");
}
});
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "1");
}
});
btn2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "2");
}
});
btn3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "3");
}
});
btn4.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "4");
}
});
btn5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "5");
}
});
btn6.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "6");
}
});
btn7.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "7");
}
});
btn8.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "8");
}
});
btn9.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText(text_result.getText() + "9");
}
});
btn_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (text_result.getText().length() != 0) {
input1 = Float.parseFloat(text_result.getText() + "");
Addition = true;
decimal = false;
text_result.setText(null);
}
}
});
btn_subtract.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (text_result.getText().length() != 0) {
input1 = Float.parseFloat(text_result.getText() + "");
Subtraction = true;
decimal = false;
text_result.setText(null);
}
}
});
btn_multi.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (text_result.getText().length() != 0) {
input1 = Float.parseFloat(text_result.getText() + "");
Multiplication = true;
decimal = false;
text_result.setText(null);
}
}
});
btn_devision.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (text_result.getText().length() != 0) {
input1 = Float.parseFloat(text_result.getText() + "");
Devision = true;
decimal = false;
text_result.setText(null);
}
}
});
btn_clear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text_result.setText("");
input1 = 0.0;
input1 = 0.0;
}
});
btn_dot.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(count==0){
count=1;
text_result.setText(text_result.getText()+".");
return;
}
else{
text_result.setText(text_result.getText()+"0.");
decimal=true;
}
}
});
btn_back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String number = text_result.getText().toString();
int input = number.length();
if (input > 0) {
text_result.setText(number.substring(0, input - 1));
}
}
});
btn_equal.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
count=0;
if ((Addition || Subtraction || Multiplication || Devision) ) {
if (text_result.getText().toString().trim().equals("")){
input2=0;
return;
}else {
input2 = Float.parseFloat(text_result.getText() + "");
}
}
if (Addition) {
text_result.setText(input1 + input2 + "");
Addition = false;
}
if (Subtraction) {
text_result.setText(input1 - input2 + "");
Subtraction = false;
}
if (Multiplication) {
text_result.setText(input1 * input2 + "");
Multiplication = false;
}
if (Devision) {
text_result.setText(input1 / input2 + "");
Devision = false;
}
}
});
}
}
当我按下点按钮时，我希望该点按钮仅在输入1中按下一次，例如:2.5 + 3.7等。
但是此代码不满足该要求-它显示2.3.4.5等。但是我只希望在一个输入中输入一个点。当我按下点按钮时，我希望该点按钮仅在输入1中按下一次，例如:2.5 + 3.7等。
最佳答案
在这里，您可以使用简单的标志进行管理。
public class MainActivity extends AppCompatActivity {
// IDs of all the numeric buttons
private int[] numericButtons = {R.id.btnZero, R.id.btnOne, R.id.btnTwo, R.id.btnThree, R.id.btnFour, R.id.btnFive, R.id.btnSix, R.id.btnSeven, R.id.btnEight, R.id.btnNine};
// IDs of all the operator buttons
private int[] operatorButtons = {R.id.btnAdd, R.id.btnSubtract, R.id.btnMultiply, R.id.btnDivide};
// TextView used to display the output
private TextView txtScreen;
// Represent whether the lastly pressed key is numeric or not
private boolean lastNumeric;
// Represent that current state is in error or not
private boolean stateError;
// If true, do not allow to add another DOT
private boolean lastDot;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find the TextView
this.txtScreen = (TextView) findViewById(R.id.txtScreen);
// Find and set OnClickListener to numeric buttons
setNumericOnClickListener();
// Find and set OnClickListener to operator buttons, equal button and decimal point button
setOperatorOnClickListener();
}
/**
* Find and set OnClickListener to numeric buttons.
*/
private void setNumericOnClickListener() {
// Create a common OnClickListener
View.OnClickListener listener = new View.OnClickListener() {
@Override
public void onClick(View v) {
// Just append/set the text of clicked button
Button button = (Button) v;
if (stateError) {
// If current state is Error, replace the error message
txtScreen.setText(button.getText());
stateError = false;
} else {
// If not, already there is a valid expression so append to it
txtScreen.append(button.getText());
}
// Set the flag
lastNumeric = true;
}
};
// Assign the listener to all the numeric buttons
for (int id : numericButtons) {
findViewById(id).setOnClickListener(listener);
}
}
/**
* Find and set OnClickListener to operator buttons, equal button and decimal point button.
*/
private void setOperatorOnClickListener() {
// Create a common OnClickListener for operators
View.OnClickListener listener = new View.OnClickListener() {
@Override
public void onClick(View v) {
// If the current state is Error do not append the operator
// If the last input is number only, append the operator
if (lastNumeric && !stateError) {
Button button = (Button) v;
txtScreen.append(button.getText());
lastNumeric = false;
lastDot = false; // Reset the DOT flag
}
}
};
// Assign the listener to all the operator buttons
for (int id : operatorButtons) {
findViewById(id).setOnClickListener(listener);
}
// Decimal point
findViewById(R.id.btnDot).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (lastNumeric && !stateError && !lastDot) {
txtScreen.append(".");
lastNumeric = false;
lastDot = true;
}
}
});
// Clear button
findViewById(R.id.btnClear).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
txtScreen.setText(""); // Clear the screen
// Reset all the states and flags
lastNumeric = false;
stateError = false;
lastDot = false;
}
});
// Equal button
findViewById(R.id.btnEqual).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onEqual();
}
});
}
/**
* Logic to calculate the solution.
*/
private void onEqual() {
// If the current state is error, nothing to do.
// If the last input is a number only, solution can be found.
if (lastNumeric && !stateError) {
// Read the expression
String txt = txtScreen.getText().toString();
// Create an Expression (A class from exp4j library)
Expression expression = new ExpressionBuilder(txt).build();
try {
// Calculate the result and display
double result = expression.evaluate();
txtScreen.setText(Double.toString(result));
lastDot = true; // Result contains a dot
} catch (ArithmeticException ex) {
// Display an error message
txtScreen.setText("Error");
stateError = true;
lastNumeric = false;
}
}
}
}