当我按下一个按钮和 EditTexts是空的它崩溃

我正在制作一个简单的计算器,作为我的第一个应用程序,我有两个EditTexts,如果我按下应用程序崩溃的 4 个计算按钮中的任何一个,我已经设置了一个 toast 消息来显示 EditText1 & amp;EditText2 是空的,如果没有根据按下的按钮进行计算...我该如何防止它崩溃?

我正在制作一个简单的计算器,作为我的第一个应用程序,我有两个EditTexts,如果我按下应用程序崩溃的 4 个计算按钮中的任何一个,我已经设置了一个 toast 消息来显示 EditText1 & amp;EditText2 是空的,如果没有根据按下的按钮进行计算...我该如何防止它崩溃?

public class MainActivity extends Activity {
    EditText number1text;
    EditText number2text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        number1text = (EditText) findViewById(R.id.num1text);
        number2text = (EditText) findViewById(R.id.num2text);
    }
    public void calcadd(View v) { // here
        if (number1text.getText().toString().isEmpty() || number2text.getText().toString().isEmpty()) {
            Toast msg = Toast.makeText(getBaseContext(),
            "You Should Put Numbers To Do Calculation",
            Toast.LENGTH_LONG);
            msg.show();
        }
        else{
        }
        Integer num1text = Integer.pInt(number1text.getText().toString());
        Integer num2text = Integer.pInt(number2text.getText().toString());
        Integer ans = num1text + num2text;
        TextView answer = (TextView) findViewById(R.id.ans);
        answer.setText("Answer:" + ans.toString());
    }
    public void calcminus(View v) { // here 
        if (number1text.getText().toString().isEmpty() || number2text.getText().toString().isEmpty()) {
            Toast msg = Toast.makeText(getBaseContext(),
            "You Should Put Numbers To Do Calculation",
            Toast.LENGTH_LONG);
            msg.show();
        }
        else{
        }
        Integer num1text = Integer.pInt(number1text.getText().toString());
        Integer num2text = Integer.pInt(number2text.getText().toString());
        Integer ans = num1text - num2text;
        TextView answer = (TextView) findViewById(R.id.ans);
        answer.setText("Answer:" + ans.toString());
    }
    public void calcdivide(View v) { // here
        if (number1text.getText().toString().isEmpty() || number2text.getText().toString().isEmpty()) {
            Toast msg = Toast.makeText(getBaseContext(),
            "You Should Put Numbers To Do Calculation",
            Toast.LENGTH_LONG);
            msg.show();
        }
        else{
        }
        Integer num1text = Integer.pInt(number1text.getText().toString());
        Integer num2text = Integer.pInt(number2text.getText().toString());
        Integer ans = num1text / num2text;
        TextView answer = (TextView) findViewById(R.id.ans);
        answer.setText("Answer:" + ans.toString());
    }
    public void calcmultiply(View v) { // here
        if (number1text.getText().toString().isEmpty() || number2text.getText().toString().isEmpty()) {
            Toast msg = Toast.makeText(getBaseContext(),
            "You Should Put Numbers To Do Calculation",
            Toast.LENGTH_LONG);
            msg.show();
        }
        else{
        }
        Integer num1text = Integer.pInt(number1text.getText().toString());
        Integer num2text = Integer.pInt(number2text.getText().toString());
        Integer ans = num1text * num2text;
        TextView answer = (TextView) findViewById(R.id.ans);
        answer.setText("Answer:" + ans.toString());
     }  
    @Override
    public boolean onCreateOptionsMenu(Menu menu) { // here
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

这是我的 activity_main.xml:

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <TextView
        android:id="@+id/num1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="@string/num1"
        android:textAppearance="?android:attr/textAppearanceMedium" 
        />
    <EditText
        android:id="@+id/num1text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/num1"
        android:layout_below="@+id/num1"
        android:ems="10"
        android:inputType="number" 
        >
        <requestFocus />
    </EditText>
    <TextView
        android:id="@+id/num2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/num1text"
        android:layout_below="@+id/num1text"
        android:text="@string/num2"
        android:textAppearance="?android:attr/textAppearanceMedium" 
        />
    <EditText
        android:id="@+id/num2text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/num2"
        android:layout_below="@+id/num2"
        android:ems="10"
        android:inputType="number" 
        />
    <TextView
        android:id="@+id/ans"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/num2text"
        android:layout_below="@+id/num2text"
        android:layout_marginTop="52dp"
        android:text="@string/anstxt"
        android:textAppearance="?android:attr/textAppearanceMedium" 
        />
    <Button
        android:id="@+id/on1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/num2text"
        android:layout_below="@+id/num2text"
        android:text="@string/btnadd" 
        android:onClick="calcadd"/>
    <Button
        android:id="@+id/Button01"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/on1"
        android:layout_alignBottom="@+id/on1"
        android:layout_toRightOf="@+id/on1"
        android:text="@string/btnminus" 
        android:onClick="calcminus"/>
    <Button
        android:id="@+id/on2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/Button01"
        android:layout_alignBottom="@+id/Button01"
        android:layout_toRightOf="@+id/Button01"
        android:text="@string/btnmultiply" 
        android:onClick="calcmultiply"/>
    <Button
        android:id="@+id/Button02"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/on2"
        android:layout_alignBottom="@+id/on2"
        android:layout_toRightOf="@+id/on2"
        android:text="@string/btndivide" 
        android:onClick="calcdivide"/>
</RelativeLayout>
8
else{
    }
    Integer num1text = Integer.pInt(number1text.getText().toString());
    Integer num2text = Integer.pInt(number2text.getText().toString());
    Integer ans = num1text + num2text;
    TextView answer = (TextView) findViewById(R.id.ans);
    answer.setText("Answer:" + ans.toString());

你在 else {} 语句之外做你的工作,你正在检查它们是否为空,这很好,但是如果它们是空的“”,你仍然尝试通过在 else 括号之外进行计算。

else{
       Integer num1text = Integer.pInt(number1text.getText().toString());
       Integer num2text = Integer.pInt(number2text.getText().toString());
       Integer ans = num1text + num2text;
       TextView answer = (TextView) findViewById(R.id.ans);
       answer.setText("Answer:" + ans.toString());
      }
1

即使这不是你目前的问题

还要确保在除法函数中检查您没有除以 0:
Integer ans = num1text / num2text;

您可以简化代码创建一个函数,该函数执行当前在每个函数中重复的事情(DRY;不要重复自己)

@ 1:例如,通过在除法函数中添加另一个 if / else:

    public void calcdivide(View v) { // here
        if (number1text.getText().toString().isEmpty() || number2text.getText().toString().isEmpty()) {
            Toast msg = Toast.makeText(getBaseContext(),
            "You Should Put Numbers To Do Calculation",
            Toast.LENGTH_LONG);
            msg.show();
        }
        else{
            Integer num1text = Integer.pInt(number1text.getText().toString());
            Integer num2text = Integer.pInt(number2text.getText().toString());
            if (num2text>0)
            {
             //only do the division if divisor > 0
             Integer ans = num1text / num2text;
             TextView answer = (TextView) findViewById(R.id.ans);
             answer.setText("Answer:" + ans.toString());
            }
            else
            {
             //e.g. show a toastmessage here
            }
        }
    }
0

在您测试 EditTexts 为空的所有四个 if 结构中,更改以下内容:

else{
}
Integer num1text = Integer.pInt(number1text.getText().toString());
Integer num2text = Integer.pInt(number2text.getText().toString());
Integer ans = num1text + num2text; // +, -, * or / depending
TextView answer = (TextView) findViewById(R.id.ans);
answer.setText("Answer:" + ans.toString());

为此(代码需要else块中):

else{
    Integer num1text = Integer.pInt(number1text.getText().toString());
    Integer num2text = Integer.pInt(number2text.getText().toString());
    Integer ans = num1text + num2text;
    TextView answer = (TextView) findViewById(R.id.ans);
    answer.setText("Answer:" + ans.toString());
}

此外,在每个 Toast 中,将getBaseContext()更改为getApplicationContext()

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