我在尝试运行项目时收到错误消息。这是一项大学任务，很简单。我相信XML是可以的。
如果您需要其他任何帮助我，请告诉我，我只是一个初学者。
package com.example.hometools;
import com.example.hometools.R;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.CheckBox;
public class HometoolsActivity extends Activity {
//Tela Principal
Button button1;
Button button2;
Button button3;
Button button4;
Button button5;
//tinta
EditText editText1t1;
EditText editText2t1;
EditText editText3t1;
EditText editText4t1;
Button button1t1;
Button button2t1; // voltar
//piso
EditText editText1t2;
EditText editText2t2;
EditText editText3t2;
Button button1t2;
Button button2t2; // voltar
//btu
EditText editText1t3;
EditText editText2t3;
EditText editText3t3;
EditText editText4t3;
CheckBox checkBox1t3;
Button button1t3;
Button button2t3; // voltar
//aquecedor
EditText editText1t4;
EditText editText2t4;
EditText editText3t4;
EditText editText4t4;
EditText editText5t4;
EditText editText6t4;
Button button1t4;
Button button2t4; // voltar
//caixa
EditText editText1t5;
EditText editText2t5;
EditText editText3t5;
Button button1t5;
Button button2t5; // voltar
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
controlePrincipal();
}
public void controlePrincipal() {
setContentView(R.layout.activity_hometools);
controleTinta(); //controla tinta
controlePiso(); //controla piso
controleBtu(); // controla btu
controleAquecedor(); // controla aquecedor
controleCaixa(); // controla caixa
}
public void controleTinta(){
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View arg0){
setContentView(R.layout.tinta);
editText1t1 = (EditText) findViewById(R.id.editText1t1);
editText2t1 = (EditText) findViewById(R.id.editText2t1);
editText3t1 = (EditText) findViewById(R.id.editText3t1);
editText4t1 = (EditText) findViewById(R.id.editText4t1);
button1t1 = (Button) findViewById(R.id.button1t1);
button1t1.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
double rendimento, quantidade,demao, area, valor_arred;
//entrada de dados
area=Double.parseDouble(editText1t1.getText().toString()) ;
demao=Double.parseDouble(editText2t1.getText().toString());
rendimento=Double.parseDouble(editText3t1.getText().toString());
quantidade = area*demao/rendimento;
quantidade = quantidade*1.1;
//arredondando o valor para cima
valor_arred = Math.ceil(quantidade);
//saída de dados
editText4t1.setText(String.valueOf(valor_arred));
}
});
button2t1.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
controlePrincipal();
}
});
}
});
}
public void controlePiso(){
button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View arg0){
setContentView(R.layout.piso);
editText1t2 = (EditText) findViewById(R.id.editText1t2);
editText2t2 = (EditText) findViewById(R.id.editText2t2);
editText3t2 = (EditText) findViewById(R.id.editText3t2);
button1t2 = (Button) findViewById(R.id.button1t2);
button1t2.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
double area, tamanho, piso, valor_arred;
//entrada de dados
area=Double.parseDouble(editText1t2.getText().toString()) ;
tamanho=Double.parseDouble(editText2t2.getText().toString());
piso=area/tamanho;
piso=piso*1.1;
//arredondando o valor para cima.
valor_arred = Math.ceil(piso);
//saída de dados
editText3t2.setText(String.valueOf(valor_arred));
}
});
button2t2.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
controlePrincipal();
}
});
}
});
}
public void controleBtu(){
button3 = (Button) findViewById(R.id.button3);
button3.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View arg0){
setContentView(R.layout.btu);
editText1t3 = (EditText) findViewById(R.id.editText1t3);
editText2t3 = (EditText) findViewById(R.id.editText2t3);
editText3t3 = (EditText) findViewById(R.id.editText3t3);
editText4t3 = (EditText) findViewById(R.id.editText4t3);
button1t3 = (Button) findViewById(R.id.button1t3);
checkBox1t3 = (CheckBox) findViewById(R.id.checkBox1t3);
button1t3.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
double area, valor_arred, BTU;
int pessoas, eletronicos;
//entrada de dados
area=Double.parseDouble(editText1t3.getText().toString()) ;
pessoas=Integer.parseInt(editText2t3.getText().toString());
eletronicos=Integer.parseInt(editText3t3.getText().toString());
//saída de dados
if (checkBox1t3.isChecked()) {
BTU=area*800+pessoas*800+eletronicos*800;
}
else {
BTU=area*600+pessoas*600+eletronicos*600;
}
valor_arred=Math.ceil(BTU);
editText4t3.setText(String.valueOf(valor_arred));
}
});
button2t3.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
controlePrincipal();
}
});
}
});
}
public void controleAquecedor(){
button4 = (Button) findViewById(R.id.button4);
button4.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View arg0){
setContentView(R.layout.aquecedor);
editText1t4 = (EditText) findViewById(R.id.editText1t4);
editText2t4 = (EditText) findViewById(R.id.editText2t4);
editText3t4 = (EditText) findViewById(R.id.editText3t4);
editText4t4 = (EditText) findViewById(R.id.editText4t4);
editText5t4 = (EditText) findViewById(R.id.editText5t4);
editText6t4 = (EditText) findViewById(R.id.editText6t4);
button1t4 = (Button) findViewById(R.id.button1t4);
button1t4.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
int a,b,c,d;
double qnec,vazao,vazaoaq,quant,quantarr;
//entrada de dados
a=Integer.parseInt(editText1t4.getText().toString()) ;
b=Integer.parseInt(editText2t4.getText().toString()) ;
c=Integer.parseInt(editText3t4.getText().toString()) ;
d=Integer.parseInt(editText4t4.getText().toString()) ;
vazaoaq=Double.parseDouble(editText5t4.getText().toString()) ;
vazao=12*a+6*b+9*c+15*d;
qnec=vazao/2;
quant=qnec/vazaoaq;
quantarr=Math.ceil(quant);
//saída de dados
editText6t4.setText(String.valueOf(quantarr));
}
});
button2t4.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
controlePrincipal();
}
});
}
});
}
public void controleCaixa(){
button1t5 = (Button) findViewById(R.id.button1t5);
button1t5.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View arg0){
setContentView(R.layout.caixa);
editText1t5 = (EditText) findViewById(R.id.editText1t5);
editText2t5 = (EditText) findViewById(R.id.editText2t5);
editText3t5 = (EditText) findViewById(R.id.editText3t5);
button1t5 = (Button) findViewById(R.id.button1t5);
button1t5.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
double minimo, intervalo, valor_arred;
int pessoas;
//entrada de dados
intervalo=Double.parseDouble(editText1t5.getText().toString()) ;
pessoas=Integer.parseInt(editText2t5.getText().toString());
minimo=pessoas*intervalo*150;
//arredondando o valor para cima.
valor_arred = Math.ceil(minimo);
//saída de dados
editText3t5.setText(String.valueOf(valor_arred));
}
});
button2t5.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0){
controlePrincipal();
}
});
}
});
}
}
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/RelativeLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
tools:context="${relativePackage}.${activityClass}" >
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginRight="16dp"
android:text="Hometools por UVA - 2015" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="57dp"
android:text="Tinta" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="37dp"
android:text="Piso" />
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="BTU" />
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button3"
android:layout_below="@+id/button3"
android:layout_marginTop="46dp"
android:text="Aquecedor" />
<Button
android:id="@+id/button5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/textView2"
android:layout_centerHorizontal="true"
android:layout_marginBottom="32dp"
android:text="Caixa d´água" />
</RelativeLayout>
这是我的logcat：
06-20 14:11:27.560: D/AndroidRuntime(824): Shutting down VM
06-20 14:11:27.560: W/dalvikvm(824): threadid=1: thread exiting with uncaught exception (group=0xb2a68ba8)
06-20 14:11:27.580: E/AndroidRuntime(824): FATAL EXCEPTION: main
06-20 14:11:27.580: E/AndroidRuntime(824): Process: com.example.hometools, PID: 824
06-20 14:11:27.580: E/AndroidRuntime(824): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hometools/com.example.hometools.HometoolsActivity}: java.lang.NullPointerException
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread.access$800(ActivityThread.java:135)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.os.Handler.dispatchMessage(Handler.java:102)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.os.Looper.loop(Looper.java:136)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread.main(ActivityThread.java:5001)
06-20 14:11:27.580: E/AndroidRuntime(824): at java.lang.reflect.Method.invokeNative(Native Method)
06-20 14:11:27.580: E/AndroidRuntime(824): at java.lang.reflect.Method.invoke(Method.java:515)
06-20 14:11:27.580: E/AndroidRuntime(824): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
06-20 14:11:27.580: E/AndroidRuntime(824): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
06-20 14:11:27.580: E/AndroidRuntime(824): at dalvik.system.NativeStart.main(Native Method)
06-20 14:11:27.580: E/AndroidRuntime(824): Caused by: java.lang.NullPointerException
06-20 14:11:27.580: E/AndroidRuntime(824): at com.example.hometools.HometoolsActivity.controleCaixa(HometoolsActivity.java:294)
06-20 14:11:27.580: E/AndroidRuntime(824): at com.example.hometools.HometoolsActivity.controlePrincipal(HometoolsActivity.java:75)
06-20 14:11:27.580: E/AndroidRuntime(824): at com.example.hometools.HometoolsActivity.onCreate(HometoolsActivity.java:66)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.Activity.performCreate(Activity.java:5231)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
06-20 14:11:27.580: E/AndroidRuntime(824): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
06-20 14:11:27.580: E/AndroidRuntime(824): ... 11 more
06-20 14:12:37.752: I/Process(824): Sending signal. PID: 824 SIG: 9
答案 0 :(得分：0)
你的错误在这里，这是一个简单的错字：
public void controleCaixa(){
button1t5 = (Button) findViewById(R.id.button1t5);
button1t5.setOnClickListener (new OnClickListener() {...}
...
}
应该是R.id.button5而不是R.id.button1t5：
public void controleCaixa(){
button5 = (Button) findViewById(R.id.button5);
button5.setOnClickListener (new OnClickListener() {...}
...
}
查看日志，很清楚：
引起：java.lang.NullPointerException 06-20 14：11：27.580： E / AndroidRuntime（824）：at com.example.hometools.HometoolsActivity.controleCaixa（HometoolsActivity.java:294） 06-20 14：11：27.580：E / AndroidRuntime（824）：