关于nullpointerexception：如何在android中处理onClickListener？

How to handle onClickListener in android?

我正在尝试编写一个简单的Android应用程序来帮助解释一些实验室结果。

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package org.android.bloodgas;

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

public class pinit extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Button interpretButton = (Button) findViewById(R.id.Interpret);

//interpretButton.setOnClickListener(this);
View.OnClickListener myhandler = new View.OnClickListener() {
@Override
public void onClick(View v) {
float inpPH, inpPO2, inpPCO2, inpHCO3, inpBE;
inpPH = Float.valueOf(findViewById(R.id.InpPH).toString()).floatValue();
inpPO2 = Float.valueOf(findViewById(R.id.InpO2).toString()).floatValue();
inpPCO2 = Float.valueOf(findViewById(R.id.InpCO2).toString()).floatValue();
inpHCO3 = Float.valueOf(findViewById(R.id.InpHCO3).toString()).floatValue();
inpBE = Float.valueOf(findViewById(R.id.InpBE).toString()).floatValue();

TextView interpretation;
interpretation = (TextView) findViewById(R.id.Interpretation);

String sResult = null;
if (inpPH < 7.35) {
// Acidosis
sResult.concat("Acidosis.");
} else {
if (inpPH > 7.45) {
// Alkalosis
sResult.concat("Alkalosis.");
} else {
// Normal acidity, 7.35-7.45
sResult.concat("Normal pH.");
}
}
interpretation.setText(sResult);
}
};

interpretButton.setOnClickListener(myhandler);

}

}

它确实编译并运行，但当我按下"解释"按钮时，它只是说应用程序......已意外停止。请再试一次。 (强制关闭)。

我对android编程完全不熟悉......所以我想这会是我犯过的一些非常愚蠢的错误，但请帮忙。谢谢。

更新：将代码更改为此(减去逻辑部分，我将在稍后完成)
按下按钮时仍然挂起。

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package org.android.bloodgas;

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

public class Pinit extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Button interpretButton = (Button) findViewById(R.id.Interpret);

View.OnClickListener myhandler = new View.OnClickListener() {
@Override
public void onClick(View v) {
float inpPH, inpPO2, inpPCO2, inpHCO3, inpBE;
inpPH = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpPH)).toString()).floatValue();
inpPO2 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpO2)).toString()).floatValue();
inpPCO2 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpCO2)).toString()).floatValue();
inpHCO3 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpHCO3)).toString()).floatValue();
inpBE = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpBE)).toString()).floatValue();
// ...
}
};

interpretButton.setOnClickListener(myhandler);

}

}

logcat的：

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12-07 03:37:02.231: WARN/dalvikvm(1074): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): FATAL EXCEPTION: main
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): java.lang.NumberFormatException: android.widget.EditText@44f47e60
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at org.apache.harmony.luni.util.FloatingPointParser.initialParse(FloatingPointParser.java:130)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at org.apache.harmony.luni.util.FloatingPointParser.parseFloat(FloatingPointParser.java:319)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at java.lang.Float.parseFloat(Float.java:291)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at java.lang.Float.valueOf(Float.java:330)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at org.android.bloodgas.Pinit$1.onClick(Pinit.java:22)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.view.View.performClick(View.java:2408)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.view.View$PerformClick.run(View.java:8816)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.os.Handler.handleCallback(Handler.java:587)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.os.Handler.dispatchMessage(Handler.java:92)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.os.Looper.loop(Looper.java:123)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at android.app.ActivityThread.main(ActivityThread.java:4627)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at java.lang.reflect.Method.invokeNative(Native Method)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at java.lang.reflect.Method.invoke(Method.java:521)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): at dalvik.system.NativeStart.main(Native Method)
12-07 03:37:02.382: WARN/ActivityManager(68): Force finishing activity org.android.bloodgas/.Pinit
12-07 03:37:02.952: WARN/ActivityManager(68): Activity pause timeout for HistoryRecord{44fbfc90 org.android.bloodgas/.Pinit}
12-07 03:37:07.761: INFO/Process(1074): Sending signal. PID: 1074 SIG: 9
12-07 03:37:09.852: INFO/ActivityManager(68): Process org.android.bloodgas (pid 1074) has died.
12-07 03:37:09.862: INFO/WindowManager(68): WIN DEATH: Window{44fa71e0 org.android.bloodgas/org.android.bloodgas.Pinit paused=false}
12-07 03:37:15.931: WARN/ActivityManager(68): Activity destroy timeout for HistoryRecord{44fbfc90 org.android.bloodgas/.Pinit}