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POCalculator program in java
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copied!<p>I am a beginner in java and I have written this code with the help of an online available program. The code attached is a part of the code which performs action when buttons of the calculator are pressed.In the CalculatorDemo class i have initialized all the buttons(b0-b24) and the TextField tf. In this class I am using char OP as a flag ,so that, when I press '+' the OP is assigned '+' and I have even checked it on command prompt. But when i press '=' ,the OP is automatically assigned '\0' and i don't know how and why. And hence, no operation is performed at all. And I don't understand where the logic is wrong. Please help </p> <pre><code> import java.awt.event.*; import java.awt.*; class CalculatorActionperform implements ActionListener { CalculatorDemo temp; public boolean foundKey; String command; String s="", s1,s2,s3,s4,s5,s6; int n; char OP; CalculatorActionperform(CalculatorDemo d) { temp=d; } public void actionPerformed(ActionEvent e) { if(e.getSource()==temp.b23) { s3=temp.tf.getText(); s4="0"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b22) { s3=temp.tf.getText(); s4="1"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b21) { s3=temp.tf.getText(); s4="2"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b20) { s3=temp.tf.getText(); s4="3"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b15) { s3=temp.tf.getText(); s4="4"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b16) { s3=temp.tf.getText(); s4="5"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b17) { s3=temp.tf.getText(); s4="6"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b12) { s3=temp.tf.getText(); s4="7"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b11) { s3=temp.tf.getText(); s4="8"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b10) { s3=temp.tf.getText(); s4="9"; s5=s3+s4; temp.tf.setText(s5); } if(e.getSource()==temp.b14) { s1=temp.tf.getText(); temp.tf.setText(""); OP='+'; } if(e.getSource()==temp.b19) { s1=temp.tf.getText(); temp.tf.setText(""); OP='-'; } if(e.getSource()==temp.b18) { s1=temp.tf.getText(); temp.tf.setText(""); OP='*'; } if(e.getSource()==temp.b13) { s1=temp.tf.getText(); temp.tf.setText(""); OP='/'; } if(e.getSource()==temp.b9) /* b9= '=' */ { s2=temp.tf.getText(); if(OP=='\0') { System.out.println("null"); } if(OP=='+') { n=Integer.parseInt(s1)+Integer.parseInt(s2); temp.tf.setText(String.valueOf(n)); } else if(OP=='-') { n=Integer.parseInt(s1)-Integer.parseInt(s2); temp.tf.setText(String.valueOf(n)); } else if(OP=='*') { n=Integer.parseInt(s1)*Integer.parseInt(s2); temp.tf.setText(String.valueOf(n)); } else if(OP=='/') { n=Integer.parseInt(s1)/Integer.parseInt(s2); temp.tf.setText(String.valueOf(n)); } } if(e.getSource()==temp.b6) { temp.tf.setText(""); } } } </code></pre>

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