简单计算器
感受：1.加强了对点击事件的了解。
2.了解到了TextView的append,setText，getText方法。
3.了解到TableLayout中的TableRow的用法。
Activity:
package com.example.calculater; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.TextView; public class MainActivity extends Activity implements OnClickListener{ private TextView tvScreen; private List<Item> items = new ArrayList<Item>(); @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tvScreen = (TextView)findViewById(R.id.tvScreen); findViewById(R.id.btn0).setOnClickListener(this); findViewById(R.id.btn1).setOnClickListener(this); findViewById(R.id.btn2).setOnClickListener(this); findViewById(R.id.btn3).setOnClickListener(this); findViewById(R.id.btn4).setOnClickListener(this); findViewById(R.id.btn5).setOnClickListener(this); findViewById(R.id.btn6).setOnClickListener(this); findViewById(R.id.btn7).setOnClickListener(this); findViewById(R.id.btn8).setOnClickListener(this); findViewById(R.id.btn9).setOnClickListener(this); findViewById(R.id.btnAdd).setOnClickListener(this); findViewById(R.id.btnSub).setOnClickListener(this); findViewById(R.id.btnMul).setOnClickListener(this); findViewById(R.id.btnDiv).setOnClickListener(this); findViewById(R.id.btnResult).setOnClickListener(this); findViewById(R.id.btnC).setOnClickListener(this); findViewById(R.id.btnBack).setOnClickListener(this); } @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; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } @Override public void onClick(View v) { // TODO Auto-generated method stub switch(v.getId()){ case R.id.btn0: tvScreen.append("0"); break; case R.id.btn1: tvScreen.append("1"); break; case R.id.btn2: tvScreen.append("2"); break; case R.id.btn3: tvScreen.append("3"); break; case R.id.btn4: tvScreen.append("4"); break; case R.id.btn5: tvScreen.append("5"); break; case R.id.btn6: tvScreen.append("6"); break; case R.id.btn7: tvScreen.append("7"); break; case R.id.btn8: tvScreen.append("8"); break; case R.id.btn9: tvScreen.append("9"); break; case R.id.btnAdd: items.add(new Item(Double.parseDouble(tvScreen.getText().toString()), Types.NUM)); checkAndCompute(); items.add(new Item(0, Types.ADD)); tvScreen.setText(""); break; case R.id.btnSub: items.add(new Item(Double.parseDouble(tvScreen.getText().toString()), Types.NUM)); checkAndCompute(); items.add(new Item(0, Types.SUB)); tvScreen.setText(""); break; case R.id.btnMul: items.add(new Item(Double.parseDouble(tvScreen.getText().toString()), Types.NUM)); checkAndCompute(); items.add(new Item(0, Types.M)); tvScreen.setText(""); break; case R.id.btnDiv: items.add(new Item(Double.parseDouble(tvScreen.getText().toString()), Types.NUM)); checkAndCompute(); items.add(new Item(0, Types.DIV)); tvScreen.setText(""); break; case R.id.btnResult: items.add(new Item(Double.parseDouble(tvScreen.getText().toString()), Types.NUM)); checkAndCompute(); tvScreen.setText(items.get(0).value+""); items.clear(); break; case R.id.btnC: tvScreen.setText(""); items.clear(); break; case R.id.btnBack: String res = tvScreen.getText().toString(); try{ tvScreen.setText(res.substring(0,res.length()-1)); } catch (Exception e){ tvScreen.setText(""); } } } public void checkAndCompute(){ if(items.size()>=3){ double a = items.get(0).value; double b = items.get(2).value; int apt = items.get(1).type; items.clear(); switch(apt){ case Types.ADD: items.add(new Item(a+b, Types.NUM)); break; case Types.SUB: items.add(new Item(a-b, Types.NUM)); break; case Types.M: items.add(new Item(a*b, Types.NUM)); break; case Types.DIV: items.add(new Item(a/b, Types.NUM)); break; } } } }
package com.example.calculater; public class Item { public Item(double value, int type){ this.value = value; this.type = type; } protected double value = 0; protected int type = 0; }
package com.example.calculater; public class Types { public static final int ADD = 1; public static final int SUB = 2; public static final int M = 3; public static final int DIV = 4; public static final int NUM = 5; }
布局：
<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/tvScreen" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="" android:gravity="right" android:textAppearance="?android:attr/textAppearanceLarge" /> <TableLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="1" > <TableRow android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/btn1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="1" /> <Button android:id="@+id/btn2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="2" /> <Button android:id="@+id/btn3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="3" /> <Button android:id="@+id/btnAdd" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="+" /> </TableRow> <TableRow android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/btn4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="4" /> <Button android:id="@+id/btn5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="5" /> <Button android:id="@+id/btn6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="6" /> <Button android:id="@+id/btnSub" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="-" /> </TableRow> <TableRow android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/btn7" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="7" /> <Button android:id="@+id/btn8" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="8" /> <Button android:id="@+id/btn9" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="9" /> <Button android:id="@+id/btnMul" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="*" /> </TableRow> <TableRow android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/btnC" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="C" /> <Button android:id="@+id/btn0" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="0" /> <Button android:id="@+id/btnResult" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="=" /> <Button android:id="@+id/btnDiv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="/" /> </TableRow> <Button android:id="@+id/btnBack" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="BackSpace" /> </TableLayout> </LinearLayout>