如何在android中处理onClickListener?

时间:2010-12-06 19:15:56

标签: android nullpointerexception

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。

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是当我按下“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。感谢。

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。

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:

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}

2 个答案:

答案 0 :(得分:3)

我看到的第一件事是你必须将它转换为

的视图类型

inpPH = Float.valueOf(findViewById(R.id.InpPH).toString()).floatValue();

其次,你是在onclickListener中调用它。所以findViewById()实际上甚至不应该编译。你需要

inpPH = Float.valueOf((TypeOfView) pinit.this.findViewById(R.id.InpPH).toString()).floatValue();

而且在java中,类应该从资本代理开始,所以它应该是

public class Pinit extends Activity{

更新

  

findViewById(R.id.InpPH)解析为   EditTex

不,不。它解析为View。在视图上调用.toString()不是您想要的。你想做什么

((EditText) pinit.this.findViewById(R.id.InpPH)).getText().toString()

答案 1 :(得分:1)

我猜你在其中一个电话中得到NumberFormatException

Float.valueOf(findViewById(R.id.InpPH).toString())

对于文档,如果string为null,则NumberFormatException得到,的长度为零或无法解析为浮点值

但是,检查logCat跟踪会得到一个干净的答案。