これの引き算みて

main.java

package net.uhfx.calculator;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

public class Main extends Activity {
	
	float number1;
	float number2;
	float answer;
	int ope;
	/**準備1で書いた変数の宣言*/
	TextView num1Text;
	TextView opeText;
	TextView num2Text;
	TextView answerText;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		//各変数を初期化
		number1 = 0;
		number2 = 0;
		answer = 0;
		ope = 0;
		
		/**準備1で書いた変数の初期化*/
		
		//ラベルを関連付け
		
		num1Text=(TextView)findViewById(R.id.num1);
		opeText=(TextView)findViewById(R.id.ope);
		num2Text=(TextView)findViewById(R.id.num2);
		answerText=(TextView)findViewById(R.id.answer);
		
		//ラベルの値を初期状態に
		
		num1Text.setText("0");
		opeText.setText("");
		num2Text.setText("");
		answerText.setText("");
	}
	public void bt1(View v){
		if(ope ==0){
			number1 = number1*10+1;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+1;
			num2Text.setText(number2+"");
		}
	}
	public void bt2(View v){
		if(ope ==0){
			number1 = number1*10+2;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+2;
			num2Text.setText(number2+"");
		}
	}
	public void bt3(View v){
		if(ope ==0){
			number1 = number1*10+3;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+3;
			num2Text.setText(number2+"");
		}
	}
	public void bt4(View v){
		if(ope ==0){
			number1 = number1*10+4;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+4;
			num2Text.setText(number2+"");
		}
	}
	public void bt5(View v){
		if(ope ==0){
			number1 = number1*10+5;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+5;
			num2Text.setText(number2+"");
		}
	}
	public void bt6(View v){
		if(ope ==0){
			number1 = number1*10+6;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+6;
			num2Text.setText(number2+"");
		}
	}
	public void bt7(View v){
		if(ope ==0){
			number1 = number1*10+7;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+7;
			num2Text.setText(number2+"");
		}
	}
	public void bt8(View v){
		if(ope ==0){
			number1 = number1*10+8;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+8;
			num2Text.setText(number2+"");
		}
	}
	public void bt9(View v){
		if(ope ==0){
			number1 = number1*10+9;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10+9;
			num2Text.setText(number2+"");
		}
	}
	public void bt0(View v){
		if(ope ==0){
			number1 = number1*10;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*10;
			num2Text.setText(number2+"");
		}
	}
	public void bt00(View v){
		if(ope ==0){
			number1 = number1*100;
			num1Text.setText(number1+"");
		} else if (ope>0){
			number2 = number2*100;
			num2Text.setText(number2+"");
		}
	}
	public void btplus(View v){
		ope=1;
		opeText.setText("+");
		num2Text.setText("0");
	}
	public void btminus(View v){
		ope=2;
		opeText.setText("-");
		num2Text.setText("0");
	}public void btmultiply(View v){
		ope=3;
		opeText.setText("*");
		num2Text.setText("0");
	}
	public void btdivide(View v){
		ope=4;
		opeText.setText("/");
		num2Text.setText("0");
	}
	//「=」ボタンが押された時
	public void btequal(View view){
		if (ope==1){
			answer=number1+number2;
			answerText.setText("="+answer);
			ope = 0;
		} else if (ope==2){
			answer=number1-number2;
			answerText.setText("="+answer);
			ope = 0;
		}else if (ope==3){
			answer = number1 * number2;
			answerText.setText("="+answer);
			ope = 0;
		}else if (ope==4){
			answer=number1/number2;
			answerText.setText("="+answer);
			ope = 0;
		}
			
		}
	//「→」ボタンが押された時
	public void btback(View v){
			if(ope==0){
			number1=number1/10-number1/10%1;
			num1Text.setText(number1+"");
		}	else if(ope>0){
			number2=number2/10-number2/10%1;
			num2Text.setText(number2+"");
		}
	}
	public void btsr(View v){
		opeText.setText("√");
		number1=(float) Math.sqrt(number1);
		answerText.setText(number1+"");
	}
	public void btpoint(View v){
		
	}
	public void btclear(View v){
		ope = 0;
		opeText.setText("");
		number1 = 0;
		num1Text.setText("");
		number2 = 0;
		num2Text.setText("");
		answer = 0;
		answerText.setText("");
	}
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}