android計算器：內存函數

Question

我目前正在設計一個android計算器應用程序，目前正在處理內存部分。如果內存不爲零，我想顯示「內存已保存」的字樣。

內存計算部分是可以運行的，但是，一旦我添加如下的語句部分，它就會崩潰。它不能完全啓動。爲什麼？

EditText Memorydisplay; 
ArrayList<Double> tempfigure = new ArrayList<Double>(); 
    double tempfigure1; 
    double memory1 = 0; 

...

Memorydisplay = (EditText) findViewById(R.id.memoryEditText); 
     mplus = (TextView) findViewById(R.id.Mplus); 
     mminus = (TextView) findViewById(R.id.Mdeduct); 
     mclear = (TextView) findViewById(R.id.MC); 
     mrecall = (TextView) findViewById(R.id.MR); 

     mplus.setOnClickListener(new View.OnClickListener() {    
      @Override 
      public void onClick(View v) { 
       tempfigure.add(Double.parseDouble(Display.getText().toString())); 
       memory1=memory1+tempfigure.get(0); 
       tempfigure1=0; 
       tempfigure.removeAll(tempfigure); 
       Display.setText("0"); 
       if (memory1 >0) { Memorydisplay.setText("Memory saved");} 
      } 
     }); 

     mminus.setOnClickListener(new View.OnClickListener() {   
      @Override 
      public void onClick(View v) { 
       tempfigure.add(Double.parseDouble(Display.getText().toString())); 
       memory1=memory1-tempfigure.get(0); 
       tempfigure1=0; 
       tempfigure.removeAll(tempfigure); 
       Display.setText("0"); 
       if (memory1 >0) { Memorydisplay.setText("Memory saved");} 
      } 
     }); 

     mclear.setOnClickListener(new View.OnClickListener() {   
      @Override 
      public void onClick(View v) { 
       memory1=0; 
       tempfigure1=0; 
       tempfigure.removeAll(tempfigure); 
       Display.setText("0"); 
       if (memory1 >0) { Memorydisplay.setText("Memory saved");} 
      } 
     }); 

     mrecall.setOnClickListener(new View.OnClickListener() {   
      @Override 
      public void onClick(View v) { 
       Display.setText(""+memory1); 
       if (memory1 >0) { Memorydisplay.setText("Memory saved");} 
      } 
     }); 

logcat的提取：

08-23 21:37:31.364: W/dalvikvm(2207): threadid=1: thread exiting with uncaught exception (group=0x409961f8) 
08-23 21:37:31.374: E/AndroidRuntime(2207): FATAL EXCEPTION: main 
08-23 21:37:31.374: E/AndroidRuntime(2207): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pearmak.jm7_calculator/com.pearmak.jm7_calculator.MainActivity}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread.access$600(ActivityThread.java:122) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.os.Handler.dispatchMessage(Handler.java:99) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.os.Looper.loop(Looper.java:137) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread.main(ActivityThread.java:4340) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at java.lang.reflect.Method.invoke(Method.java:511) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at dalvik.system.NativeStart.main(Native Method) 
08-23 21:37:31.374: E/AndroidRuntime(2207): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at com.pearmak.jm7_calculator.MainActivity.onCreate(MainActivity.java:88) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.Activity.performCreate(Activity.java:4465) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) 
08-23 21:37:31.374: E/AndroidRuntime(2207):  ... 11 more 
08-23 21:37:39.748: I/Process(2207): Sending signal. PID: 2207 SIG: 9 

Answer 1

您是鑄造一個TextView到EditText上，因此除外。

您必須初始化爲Memorydisplay作爲TextView。

您需要將其更改爲EditText Memorydisplay;的定義。

注意：上面的代碼應該可以解決您的問題，但我不明白爲什麼你需要一個EditText來顯示內存狀態。一個TextView應該足夠了。爲什麼不使用下面的代碼？

TextView Memorydisplay; 
Memorydisplay = (TextView) findViewById(R.id.memoryTextView); 

無論如何，這是你的選擇。祝你好運！ :)