java - TextView 値の受け渡しエラー

Question

数日前にこの質問をしましたが、間違った logcat エラーを含めたことに気付きました。これには正しい logcat が含まれています...

ユーザーが値を入力できるようにするアプリを作成しており、それらはチャートにプロットするために使用されます。ここ数日、私は特定の問題に行き詰まっていて、それを乗り越えることができないようです. ユーザーは 2 つの値を入力し、これら 3 つの値から計算されて内部クラスに渡され、グラフにプロットされます。これらの値は TextView 形式です。私はそれをテストしているので、ほとんどのコードが機能することを知っています。エラーが TextView 値と関係があることはかなり確信しています。以下は、計算とグラフの描画に使用されるコードです。

package com.example.ballanimation;

import java.math.BigDecimal;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class calculations extends Activity {

EditText firstVal, secondVal;
TextView resultA, resultB, resultC;
Button button3;
BigDecimal firstNum, secNum;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.calculations_page);

button3 = (Button) findViewById(R.id.button3);

firstVal = (EditText) findViewById(R.id.editTXT1);
secondVal = (EditText) findViewById(R.id.editTXT2);

resultA = (TextView) findViewById(R.id.result1);
resultB = (TextView) findViewById(R.id.result2);
resultC = (TextView) findViewById(R.id.result3);


button3.setOnClickListener(new View.OnClickListener() {

    public void onClick(View v) {
        // TODO Auto-generated method stub
        firstNum = new BigDecimal(firstVal.getText().toString());
        secNum = new BigDecimal(secondVal.getText().toString());
        resultA.setText(firstNum.add(secNum).toString());
        resultB.setText(firstNum.subtract(secNum).toString());
        resultC.setText(firstNum.multiply(secNum).toString());

    }
});


}

class TestA1 extends View{

public TestA1(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
}

public void onDraw(Canvas canvas){
    super.onDraw(canvas);

    String TestA = resultA.getText().toString();
    String TestB = resultB.getText().toString();
    String TestC = resultC.getText().toString();

    int A = Integer.parseInt(TestA);
    int B = Integer.parseInt(TestB);
    int C = Integer.parseInt(TestC);

    Paint red = new Paint();
    red.setColor(Color.RED);
    red.setStyle(Paint.Style.STROKE);

    Paint black = new Paint();
    black.setColor(Color.BLACK);
    black.setStyle(Paint.Style.STROKE);

    canvas.drawCircle(A, B, C, black);
    canvas.drawCircle(canvas.getWidth()*1/2, canvas.getHeight()*3/8,    canvas.getWidth()*475/1000, black);
    canvas.drawCircle(canvas.getWidth()*5/8, canvas.getWidth()*5/8, canvas.getWidth()*349/1000, black);
    canvas.drawCircle(canvas.getWidth()*6/8, canvas.getWidth()*5/8, canvas.getWidth()*228/1000, black);
    canvas.drawCircle(canvas.getWidth()*7/8, canvas.getWidth()*5/8, canvas.getWidth()*103/1000, black);

    canvas.drawLine((canvas.getWidth()-canvas.getWidth()) + 10, (canvas.getHeight()*3)/8, canvas.getWidth() - 10, (canvas.getHeight()*3)/8, black);

    float a, b, c, d, e, f, g, h, i, j, k, l;

    a = 90;   //degrees
    b = 90;
    c = 90;
    d = 50;
    e = 90;
    f = 134;
    g = -90;
    h = -90;
    i = -90;
    j = -50;
    k = -90;
    l = -134;

    RectF arc0 = new RectF();
    RectF arc1 = new RectF();
    RectF arc2 = new RectF();
    RectF arc3 = new RectF();
    RectF arc4 = new RectF();
    RectF arc5 = new RectF();

    /*left  The X coordinate of the left side of the rectangle 
    top  The Y coordinate of the top of the rectangle 
    right  The X coordinate of the right side of the rectangle 
    bottom  The Y coordinate of the bottom of the rectangle  */



    arc0.set(canvas.getWidth()*1/2, canvas.getHeight()*-139/700, canvas.getWidth()*100/69, canvas.getHeight()*3/8); 
    arc1.set(canvas.getWidth()*-6/112, canvas.getHeight()*-80/100, canvas.getWidth()*195/100, canvas.getHeight()*72/192);   
    arc2.set(canvas.getWidth()*7/10, canvas.getHeight()*70/700, canvas.getWidth()*125/100, canvas.getHeight()*3/8); 
    arc3.set(canvas.getWidth()/2, canvas.getHeight()*3/8, canvas.getWidth()*100/69, canvas.getHeight()*91/96);
    arc4.set(canvas.getWidth()*-8/112, canvas.getHeight()*3/8, canvas.getWidth()*195/100, canvas.getHeight()*150/100);
    arc5.set(canvas.getWidth()*7/10, canvas.getHeight()*3/8, canvas.getWidth()*125/100, canvas.getHeight()*65/100);


    /*oval  The bounds of oval used to define the shape and size of the arc 
    startAngle  Starting angle (in degrees) where the arc begins 
    sweepAngle  Sweep angle (in degrees) measured clockwise 
    useCenter  If true, include the center of the oval in the arc, and close it if it is being stroked. This will draw a wedge 
    paint  The paint used to draw the arc  */

    canvas.drawArc(arc0, a, b, false, red);
    canvas.drawArc(arc1, c, d, false, red);
    canvas.drawArc(arc2, e, f, false, red);
    canvas.drawArc(arc3, g, h, false, red);
    canvas.drawArc(arc4, i, j, false, red);
    canvas.drawArc(arc5, k, l, false, red);

}
}
}

私が得ているLogcatエラーは次のとおりです。

01-08 11:54:05.436: D/dalvikvm(714): GC_FOR_ALLOC freed 42K, 3% free 8053K/8259K, paused 66ms, total 69ms
01-08 11:54:05.436: I/dalvikvm-heap(714): Grow heap (frag case) to 8.305MB for 412064-byte allocation
01-08 11:54:05.596: D/dalvikvm(714): GC_FOR_ALLOC freed 1K, 3% free 8455K/8711K, paused 55ms, total 55ms
01-08 11:54:05.647: D/dalvikvm(714): GC_FOR_ALLOC freed 0K, 3% free 8455K/8711K, paused 48ms, total 48ms
01-08 11:54:05.666: I/dalvikvm-heap(714): Grow heap (frag case) to 9.189MB for 928216-byte allocation
01-08 11:54:05.836: D/dalvikvm(714): GC_CONCURRENT freed 0K, 4% free 9361K/9671K, paused 98ms+9ms, total 173ms
01-08 11:54:05.836: D/dalvikvm(714): WAIT_FOR_CONCURRENT_GC blocked 3ms
01-08 11:54:06.186: D/gralloc_goldfish(714): Emulator without GPU emulation detected.
01-08 11:54:07.856: I/Choreographer(714): Skipped 79 frames!  The application may be doing too much work on its main thread.
01-08 11:54:25.786: D/AndroidRuntime(714): Shutting down VM
01-08 11:54:25.816: W/dalvikvm(714): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
01-08 11:54:25.866: E/AndroidRuntime(714): FATAL EXCEPTION: main
01-08 11:54:25.866: E/AndroidRuntime(714): java.lang.NullPointerException
01-08 11:54:25.866: E/AndroidRuntime(714):  at com.example.ballanimation.calculations$TestA1.onDraw(calculations.java:83)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13458)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13342)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.drawChild(ViewGroup.java:2929)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2799)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13461)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.widget.FrameLayout.draw(FrameLayout.java:467)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13342)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.drawChild(ViewGroup.java:2929)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2799)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13340)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.drawChild(ViewGroup.java:2929)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2799)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.View.draw(View.java:13461)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.widget.FrameLayout.draw(FrameLayout.java:467)
01-08 11:54:25.866: E/AndroidRuntime(714):  at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2183)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl.drawSoftware(ViewRootImpl.java:2256)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl.draw(ViewRootImpl.java:2151)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2019)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1830)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.Choreographer.doCallbacks(Choreographer.java:555)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.Choreographer.doFrame(Choreographer.java:525)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.os.Handler.handleCallback(Handler.java:615)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.os.Handler.dispatchMessage(Handler.java:92)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.os.Looper.loop(Looper.java:137)
01-08 11:54:25.866: E/AndroidRuntime(714):  at android.app.ActivityThread.main(ActivityThread.java:4745)
01-08 11:54:25.866: E/AndroidRuntime(714):  at java.lang.reflect.Method.invokeNative(Native Method)
01-08 11:54:25.866: E/AndroidRuntime(714):  at java.lang.reflect.Method.invoke(Method.java:511)
01-08 11:54:25.866: E/AndroidRuntime(714):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
01-08 11:54:25.866: E/AndroidRuntime(714):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-08 11:54:25.866: E/AndroidRuntime(714):  at dalvik.system.NativeStart.main(Native Method)
01-08 11:54:28.535: I/Process(714): Sending signal. PID: 714 SIG: 9

エラーが次の行に含まれていると確信しています。

                    String TestA = resultA.getText().toString();
        String TestB = resultB.getText().toString();
        String TestC = resultC.getText().toString();

TextView 値を渡す方法に何か問題があるに違いありませんが、どこに問題があるのかわかりません。

どんな助けでも大歓迎です。

score 0 · Accepted Answer

これを試してください：

        String TestA="",TestB="",TestC="";

        if(!resultA.getText().toString().equals("")) 
            TestA = resultA.getText().toString();
        if(!resultB.getText().toString().equals("")) 
            TestB = resultB.getText().toString();
        if(!resultC.getText().toString().equals("")) 
            TestC = resultC.getText().toString();

それ以外の：

        String TestA = resultA.getText().toString();
        String TestB = resultB.getText().toString();
        String TestC = resultC.getText().toString();

ありがとう。

score 0 · Accepted Answer

クラス名「calculations」は小文字で始まり、大文字の「C」で始まるとします。

score 0 · Accepted Answer

String TestA = resultA.getText().toString();
String TestB = resultB.getText().toString();
String TestC = resultC.getText().toString();

このコードを TestA1 クラスの外に置き、この変数をクラス内で使用します。それが役立つことを願っています。

score 0 · Accepted Answer

こんにちは、NullPointerException の考えられるいくつかの理由

1) まず、テキストビューの文字列が入力されていない可能性があります。

2) 次に、それぞれのテキストビューの ID ( ) が、アクティビティで使用しているR.id.result1, R.id.result2, R.id.result3同じレイアウト ( ) に存在しない可能性があります。R.layout.calculations_page

最初のシナリオでは、Pratik Sharma のアドバイスに従うことができます

null の 2 回目のチェック用resultA, resultB, resultC

例えば

if(resultA!=null){
}

java - TextView 値の受け渡しエラー

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