android 计算器（2）

package com.example.calculater;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends ActionBarActivity {public final static String EXTRA_MESSAGE = "calulater.MESSAGE";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.fragment_main);             }        public void Add(View view){    try{     EditText editText1 = (EditText) findViewById(R.id.num1);       EditText editText2 = (EditText) findViewById(R.id.num2);        String message1 = editText1.getText().toString();        String message2 = editText2.getText().toString();     float result;     result=Float.parseFloat(message1)+Float.parseFloat(message2);      TextView textview=(TextView)findViewById(R.id.result1);     textview.setText(String.valueOf(result));    }    catch(NumberFormatException e1){Toast.makeText(this, "only input integer please", 3).show();}}    public void Sub(View view){    try{     EditText editText1 = (EditText) findViewById(R.id.num1);       EditText editText2 = (EditText) findViewById(R.id.num2);        String message1 = editText1.getText().toString();        String message2 = editText2.getText().toString();     float result;     result=Float.parseFloat(message1)-Float.parseFloat(message2);     TextView textview=(TextView)findViewById(R.id.result1);     textview.setText(String.valueOf(result));    }    catch(NumberFormatException e2){Toast.makeText(this, "only input integer please", 3).show();}    }        public void Mul(View view){    try{     EditText editText1 = (EditText) findViewById(R.id.num1);       EditText editText2 = (EditText) findViewById(R.id.num2);        String message1 = editText1.getText().toString();        String message2 = editText2.getText().toString();     float result;     result=Float.parseFloat(message1)*Float.parseFloat(message2);     TextView textview=(TextView)findViewById(R.id.result1);     textview.setText(String.valueOf(result));    }    catch(NumberFormatException e2){Toast.makeText(this, "only input integer please", 3).show();}    }    public void Div(View view){    try{     EditText editText1 = (EditText) findViewById(R.id.num1);       EditText editText2 = (EditText) findViewById(R.id.num2);        String message1 = editText1.getText().toString();        String message2 = editText2.getText().toString();     float result;     result=Float.parseFloat(message1)/Float.parseFloat(message2);     TextView textview=(TextView)findViewById(R.id.result1);     textview.setText(String.valueOf(result));    }    catch(NumberFormatException e2){Toast.makeText(this, "only input integer please", 3).show();}    }  /*   @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);    }}

源码如上，主要是添加button的单击事件的处理方法add,sub,mul,div.用了try-catch 结构处理异常。ps:numberFormatException是java提供的数字格式化异常。做了toast,发现输入的数据不是数字就会toast个提示。toast最后结尾要有个show()函数，否则显示不出来。

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