java - 请帮我调试错误 :java. lang.NullPointerException

Question

我正在尝试将用户输入值从一个 Activity 传递到另一个 Activity 。在第二个 Activity 中，我对数据进行一些操作并显示最终值。但它给出了一个空指针异常。

我的代码有什么错误？

第一个 Activity :

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fourth);

    final EditText et;
    final Button b;

    et = (EditText) findViewById(R.id.editText1);
    b = (Button) findViewById(R.id.button1);

    b.setOnClickListener(new OnClickListener() {


        @Override
        public void onClick(View v) 
{
               Intent intent = new Intent(Fourth.this, Fifth.class);
               intent.putExtra("thetext", et.getText().toString());
               startActivity(intent);

            Intent intentnew = new Intent(Fourth.this, Sixth.class);
            intentnew.putExtra("thetext", et.getText().toString());            
            startActivity(intentnew);   

}

接收并显示数据的下一个 Activity 。(代码 fragment )

TextView tvr = (TextView) findViewById(R.id.finalremark);


double wto=Double.parseDouble(getIntent().getExtras().getString("the text"));

                            double z=wto*0.75;

                            String weight= Double.toString(z); 

                            tvr.setText(weight);

日志猫

09-03 11:11:06.069: E/AndroidRuntime(30262): FATAL EXCEPTION: main
09-03 11:11:06.069: E/AndroidRuntime(30262): java.lang.NullPointerException
09-03 11:11:06.069: E/AndroidRuntime(30262):    at    com.example.footforthought.Sixth$2.handleMessage(Sixth.java:380)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at  android.os.Handler.dispatchMessage(Handler.java:99)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at android.os.Looper.loop(Looper.java:137)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at android.app.ActivityThread.main(ActivityThread.java:4517)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at java.lang.reflect.Method.invokeNative(Native Method)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at java.lang.reflect.Method.invoke(Method.java:511)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
09-03 11:11:06.069: E/AndroidRuntime(30262):    at dalvik.system.NativeStart.main(Native Method)
09-03 11:11:17.969: I/Process(30262): Sending signal. PID: 30262 SIG: 9

Answer 1

'thetext'..您在其间添加了空格..删除空格

double wto=Double.parseDouble(getIntent().getExtras().getString("thetext"));//here remove the space in name 'thetext'

                            double z=wto*0.75;

                            String weight= Double.toString(z); 

                            tvr.setText(weight);