0

这是 Java 中的小费计算器应用程序。如果两个字段都没有填写，它应该在 a 中显示一条错误消息TextView，但它只会冻结应用程序......有什么提示吗？

package tip.calculator;


import android.os.Bundle;
import android.app.Activity;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.TextView;
import android.view.View;
import android.widget.Button;




public class TipCalculator extends Activity 
{

private Button enter;
EditText myEditField ;
EditText myEditField2;
float percentage = 0;
float percentageInp = 0;
float billAmount = 0;
double output = 0; 
String output1 = "";
Button clearButton ;
TextView textView;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    myEditField = (EditText) findViewById(R.id.percentText);
    enter = (Button)findViewById(R.id.button1);
    myEditField2 = (EditText) findViewById(R.id.billText);
    clearButton = (Button) findViewById(R.id.clearButton);


    enter.setOnClickListener(new OnClickListener() {


        public void onClick(View v) {

             TextView errors;
             textView = (TextView) findViewById(R.id.textView1);
             errors = (TextView) findViewById(R.id.errorText);    




             if(myEditField.getText().equals("")){
                 errors.setText("Percent must be filled in");


             }

             if(myEditField.getText().equals("")){
                 errors.setText("Bill Amount must be filled in");

             }




            percentageInp = Float.parseFloat(myEditField.getText().toString());
            billAmount = Float.parseFloat(myEditField2.getText().toString());

            percentage = ((float)percentageInp /100);

            output = (double)(billAmount * percentage);

            double result = output * 100;
            result = Math.round(result);
            result = result / 100;

            output1 = Double.toString(result);

            textView.setText(output1 + " $");

        }
    });

    clearButton.setOnClickListener(new OnClickListener() {

        public void onClick(View arg0) {

            percentage = 0;
            output = 0;
            output1 = "";

            TextView textView = (TextView)findViewById(R.id.errorText);
            textView.setText("");

            TextView textView2 = (TextView)findViewById(R.id.percentText);
            textView2.setText("");

            TextView textView3 = (TextView)findViewById(R.id.billText);
            textView3.setText("");


            TextView textView1 = (TextView)findViewById(R.id.textView1);
            textView1.setText("");


            percentageInp = 0;
            billAmount = 0;

            myEditField.clearComposingText();
            myEditField2.clearComposingText();



            return;
        }


    });
}*

}

这是布局xml（由请求提供）...

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/errorText"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:onClick="onEnterClick" >

    <EditText
        android:id="@+id/billText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:ems="10"
        android:hint="Bill Amount"
        android:inputType="numberDecimal|textAutoComplete"
        android:singleLine="true" />

    <EditText
        android:id="@+id/percentText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/billText"
        android:layout_below="@+id/billText"
        android:ems="10"
        android:hint="Percent"
        android:inputType="number"
        android:singleLine="true" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/percentText"
        android:layout_centerHorizontal="true"
        android:text="Calculate" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/percentText"
        android:layout_toRightOf="@+id/billText"
        android:text="$"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/percentText"
        android:layout_alignLeft="@+id/textView2"
        android:text="%"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/clearButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button1"
        android:layout_centerHorizontal="true"
        android:text="Clear" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/textView3"
        android:layout_below="@+id/clearButton"
        android:text="Solution Will Appear Here"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button1"
        android:layout_below="@+id/errorText"
        android:text=""
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

这是 LogCat 输出（仅限错误）

08-01 20:49:08.424: E/(13643): URE: SkPaint in getMeasureCacheProc index: 2
08-01 20:49:08.689: E/(13643): URE: SkPaint in getMeasureCacheProc index: 2
08-01 20:49:10.844: E/(13643): URE: SkPaint in getMeasureCacheProc index: 2
08-01 20:49:12.074: E/(13643): URE: SkPaint in getMeasureCacheProc index: 2
08-01 20:49:12.254: E/(13643): URE: SkPaint in getMeasureCacheProc index: 2
08-01 20:49:16.649: E/AndroidRuntime(13643): FATAL EXCEPTION: main
08-01 20:49:16.649: E/AndroidRuntime(13643): java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView
08-01 20:49:16.649: E/AndroidRuntime(13643):    at tip.calculator.TipCalculator$2.onClick(TipCalculator.java:91)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.view.View.performClick(View.java:3620)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.view.View$PerformClick.run(View.java:14292)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.os.Handler.handleCallback(Handler.java:605)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.os.Handler.dispatchMessage(Handler.java:92)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.os.Looper.loop(Looper.java:137)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at android.app.ActivityThread.main(ActivityThread.java:4507)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at java.lang.reflect.Method.invokeNative(Native Method)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at java.lang.reflect.Method.invoke(Method.java:511)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
08-01 20:49:16.649: E/AndroidRuntime(13643):    at dalvik.system.NativeStart.main(Native Method)
4

2 回答 2

0

为什么你return有onClick？你也有一个*倒数第二个}我不知道这是否能解决你的问题，但它引起了我的注意。

于 2012-08-02T03:32:28.357 回答
0

从您的 LogCat 中，我知道 ID 没有TextViewerrorText ，但是您在编译时看不到任何错误，因为您有一个RelativeLayout带有此 ID 的错误；但是你ClassCastException在运行时得到错误。

 errors = (TextView) findViewById(R.id.errorText);

此外，请始终使用""..equals(myEditField.getText())（myEditField.getText().equals("")即首先使用硬编码值）。

否则，如果您EditText为空，myEditField.getText()将返回null，因此尝试在null上使用 equals() 方法时会出错。

或者，您可以使用myEditField.getText().length() = 0来检查 是否EditText为空。

于 2012-08-02T08:24:38.867 回答