了java.lang.RuntimeException無法啓動活動componentinfo

Question

我在這段代碼有此錯誤

了java.lang.RuntimeException無法啓動活動componentinfo

package estimatewall.example.com.estimatewall; 

import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 

public class MainActivity extends ActionBarActivity { 

    EditText inputTxt; 
    EditText inputTxt1; 
    TextView setText; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     inputTxt = (EditText) findViewById(R.id.editText); 

     // Store EditText in Variable 

     int val = Integer.parseInt(inputTxt.getText().toString()); 

     inputTxt1 = (EditText) findViewById(R.id.editText2); 

     // Store EditText in Variable 

     int val1 = Integer.parseInt(inputTxt1.getText().toString()); 

     float block1,block2; 
     final float sum; 
     block1=(val*12)/7; 
     block2=(val1*12)/10; 
     sum=block1*block2; 

     Button button = (Button) findViewById(R.id.button); 
     button.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View v) { 

       // Perform action on click 
       try { 
        TextView textView = (TextView) findViewById(R.id.textView3); 
        textView.setText("" + sum); 
       }catch (Exception e) 
       { 
        e.printStackTrace(); 
       } 


      } 
     }); 





    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.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(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

Answer 1

可能越來越NumberFormatException因爲這裏：

int val = Integer.parseInt(inputTxt.getText().toString()); 

試圖c反轉null至int。

使用inputTxt.getText()內的點擊監聽按鈕的onClick方法由用戶來獲取值輸入EDITTEXT或設置XML一些默認值都EditText上的作爲android:text="0"