Android-计算器
16lz
2022-01-16
Android：计算器
前端界面(布局文件) ：线性布局+组件：Button,TextView，使用权重来控制每个按钮的大小。
java代码(加载界面，执行组件事件)：实例化组件，绑定监听事件，处理事件。button的setOnClickListener（按钮的监听事件）
布局文件clac.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:id="@+id/txtResult" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="显示结果" android:textSize="30sp" android:gravity="right"/> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btnClean" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="C" /> <Button android:id="@+id/btnDel" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="2" android:text="DEL" /> <Button android:id="@+id/btnAdd" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="+" /> LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btn1" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="1" /> <Button android:id="@+id/btn2" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="2" /> <Button android:id="@+id/btn3" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="3" /> <Button android:id="@+id/btnSub" android:layout_width="0dp" android:layout_weight="1" android:layout_height="wrap_content" android:text="-"/>LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btn4" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="4" /> <Button android:id="@+id/btn5" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="5" /> <Button android:id="@+id/btn6" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="6" /> <Button android:id="@+id/btnMul" android:layout_width="0dp" android:layout_weight="1" android:layout_height="wrap_content" android:text="*"/>LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btn7" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="7" /> <Button android:id="@+id/btn8" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="8" /> <Button android:id="@+id/btn9" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="9" android:visibility="visible" /> <Button android:id="@+id/btnDivide" android:layout_width="0dp" android:layout_weight="1" android:layout_height="wrap_content" android:text="/"/> LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btn0" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="0" /> <Button android:id="@+id/btnDoc" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="." /> <Button android:id="@+id/btnEqual" android:layout_width="0dp" android:layout_weight="2" android:layout_height="wrap_content" android:text="="/> LinearLayout>LinearLayout>java代码MainActivity.java
package com.example.qq.mycalculatorapplication;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;public class MainActivity extends AppCompatActivity implements View.OnClickListener { //实例化按钮 private Button btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9,btnDoc; private Button btnAdd, btnSub, btnDivide, btnMul, btnEqual,btnDel,btnClean; private StringBuffer digitalA = new StringBuffer();//第一个数 private StringBuffer digitalB = new StringBuffer();//第二个数 private boolean isFirstNum = true;//判断是第一个数字还是第二个数字 private int operate;//做标记，判断+，-，*，/ private TextView txtResult;//结果 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.calc); //找到相应的按钮，用于绑定 btn0 = (Button) this.findViewById(R.id.btn0); btn1 = (Button) this.findViewById(R.id.btn1); btn2 = (Button) this.findViewById(R.id.btn2); btn3 = (Button) this.findViewById(R.id.btn3); btn4 = (Button) this.findViewById(R.id.btn4); btn5 = (Button) this.findViewById(R.id.btn5); btn6 = (Button) this.findViewById(R.id.btn6); btn7 = (Button) this.findViewById(R.id.btn7); btn8 = (Button) this.findViewById(R.id.btn8); btn9 = (Button) this.findViewById(R.id.btn9); btnDoc=(Button)this.findViewById(R.id.btnDoc); txtResult = (TextView) this.findViewById(R.id.txtResult); btnAdd = (Button) this.findViewById(R.id.btnAdd); btnSub = (Button) this.findViewById(R.id.btnSub); btnMul = (Button) this.findViewById(R.id.btnMul); btnDivide = (Button) this.findViewById(R.id.btnDivide); btnDel = (Button) this.findViewById(R.id.btnDel); btnClean = (Button) this.findViewById(R.id.btnClean); btnEqual=(Button)this.findViewById(R.id.btnEqual); //绑定数字按钮，事件监听器 btn0.setOnClickListener(this); btn1.setOnClickListener(this); btn2.setOnClickListener(this); btn3.setOnClickListener(this); btn4.setOnClickListener(this); btn5.setOnClickListener(this); btn6.setOnClickListener(this); btn7.setOnClickListener(this); btn8.setOnClickListener(this); btn9.setOnClickListener(this); btnDoc.setOnClickListener(this); //绑定符号按钮，事件监听器(+,-,*,/,=,C,Del) btnAdd.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if(digitalA.length()==0){ //没有数字输入，就不需要做加法 return; } operate = 0; txtResult.setText("+"); isFirstNum = false; } }); btnSub.setOnClickListener((v) -> { if(digitalA.length()==0){ return; } operate = 1; txtResult.setText("-"); isFirstNum = false; }); btnMul.setOnClickListener((v) -> { if(digitalA.length()==0){ return; } operate = 2; txtResult.setText("*"); isFirstNum = false; }); btnDivide.setOnClickListener((v) -> { if(digitalA.length()==0){ return; } operate = 3; txtResult.setText("/"); isFirstNum = false; }); btnEqual.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if(digitalA.length()==0){ return; } float a = Float.parseFloat(digitalA.toString()); float b = Float.parseFloat(digitalB.toString()); float c = 0; switch (operate) { case 0: c = a + b; txtResult.setText(c + ""); break; case 1: c = a - b; txtResult.setText(c + ""); break; case 2: c = a * b; txtResult.setText(c + ""); break; case 3: c = a / b; txtResult.setText(c + ""); break; } isFirstNum = true; digitalA = new StringBuffer(); digitalB = new StringBuffer(); } }); btnClean.setOnClickListener((v) -> { if(digitalA.length()>=0&&isFirstNum){ digitalA=new StringBuffer(); txtResult.setText("0"); } else if(digitalB.length()>=0&&!isFirstNum){ digitalA=new StringBuffer(); digitalB=new StringBuffer(); txtResult.setText("0"); } isFirstNum = true; digitalA = new StringBuffer(); digitalB = new StringBuffer(); }); btnDel.setOnClickListener(new View.OnClickListener(){ @Override public void onClick(View v) { if(digitalA.length()>0&&isFirstNum){ String temp=digitalA.substring(0,digitalA.length()-1);//取子串，即删除最后一位 digitalA=new StringBuffer(); digitalA.append(temp); txtResult.setText(digitalA.toString()); } else if(digitalA.length()==0&&isFirstNum){ //没有输入按删除，返回0 digitalA=new StringBuffer(); txtResult.setText("0"); } else if(digitalB.length()>0&&!isFirstNum){ String temp=digitalB.substring(0,digitalB.length()-1);//取子串，即删除最后一位 digitalB=new StringBuffer(); digitalB.append(temp); txtResult.setText(digitalB.toString()); } else if(digitalB.length()==0&&!isFirstNum){ //没有输入按删除，返回0 digitalB=new StringBuffer(); txtResult.setText("0"); } } }); }//数字的显示 public void onClick(View v) { //String str = txtResult.toString(); switch (v.getId()) { case R.id.btn0: if(isFirstNum) { digitalA.append("0"); txtResult.setText(digitalA); }else { digitalB.append("0"); txtResult.setText(digitalB); } break; case R.id.btn1: if(isFirstNum) { digitalA.append("1"); txtResult.setText(digitalA); }else { digitalB.append("1"); txtResult.setText(digitalB); } break; case R.id.btn2: if(isFirstNum) { digitalA.append("2"); txtResult.setText(digitalA); }else { digitalB.append("2"); txtResult.setText(digitalB); } break; case R.id.btn3: if(isFirstNum) { digitalA.append("3"); txtResult.setText(digitalA); }else { digitalB.append("3"); txtResult.setText(digitalB); } break; case R.id.btn4: if(isFirstNum) { digitalA.append("4"); txtResult.setText(digitalA); }else { digitalB.append("4"); txtResult.setText(digitalB); } break; case R.id.btn5: if(isFirstNum) { digitalA.append("5"); txtResult.setText(digitalA); }else { digitalB.append("5"); txtResult.setText(digitalB); } break; case R.id.btn6: if(isFirstNum) { digitalA.append("6"); txtResult.setText(digitalA); }else { digitalB.append("6"); txtResult.setText(digitalB); } break; case R.id.btn7: if(isFirstNum) { digitalA.append("7"); txtResult.setText(digitalA); }else { digitalB.append("7"); txtResult.setText(digitalB); } break; case R.id.btn8: if(isFirstNum) { digitalA.append("8"); txtResult.setText(digitalA); }else { digitalB.append("8"); txtResult.setText(digitalB); } break; case R.id.btn9: if(isFirstNum) { digitalA.append("9"); txtResult.setText(digitalA); }else { digitalB.append("9"); txtResult.setText(digitalB); } break; case R.id.btnDoc: if(isFirstNum) { digitalA.append("."); txtResult.setText(digitalA); }else { digitalB.append("."); txtResult.setText(digitalB); } break; } } }运行结果图
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