java - 在 eclipse 中生成随机数时崩溃

package com.example.gameofguessing;

import java.util.Random;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Screen extends Activity {
    String lowerlimit1;
    String upperlimit1;
    int ulimit;
    int llimit;
    int count;
    Intent nextscreen = Screen.this.getIntent();

    {
        lowerlimit1 = nextscreen.getStringExtra("llimit");
        upperlimit1 = nextscreen.getStringExtra("ulimit");
        // limit.setText(lowerlimit1);
        llimit = Integer.parseInt(lowerlimit1);
        ulimit = Integer.parseInt(upperlimit1);
    }
    Random random = new Random();
    int randumnum = random.nextInt(ulimit - llimit + 1) + llimit;
    Button go;
    TextView limit;
    EditText number;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_screen);

        number = (EditText) findViewById(R.id.editText1);
        go = (Button) findViewById(R.id.button1);
        limit = (TextView) findViewById(R.id.textView1);
        go.setOnClickListener(input);

    }
    OnClickListener input = new OnClickListener() {
        @Override
        public void onClick(View v) {

            if(llimit <= randumnum) {
                limit.setText("Too low");
                number.setText("");
                count = +1;

            }
            else if(llimit >= randumnum) {
                limit.setText("Too high");
                number.setText("");
                count = +1;
            }
            else {
                count = +1;
                limit.setText("You got the number after" + count + "tries");
            }
        }
    };
}

这就是到目前为止，我不知道为什么我的模拟器不断崩溃。肯定与随机数或意图有关。
请帮忙

最佳答案

尝试这个。问题在于您正在执行getIntent()方法之前调用onCreate。因此，接收到的意图尚未初始化和加载，因此您得到一个NullPointerException。

 package com.example.gameofguessing;

import java.util.Random;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Screen extends Activity {
    String lowerlimit1;
    String upperlimit1;
    int ulimit;
    int llimit;
    int count;
    int randumnum
    Button go;
    TextView limit;
    EditText number;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_screen);

        number = (EditText) findViewById(R.id.editText1);
        go = (Button) findViewById(R.id.button1);
        limit = (TextView) findViewById(R.id.textView1);
        go.setOnClickListener(input);

        Intent nextscreen = Screen.this.getIntent();
        lowerlimit1 = nextscreen.getStringExtra("llimit");
        upperlimit1 = nextscreen.getStringExtra("ulimit");
        // limit.setText(lowerlimit1);
        llimit = Integer.parseInt(lowerlimit1);
        ulimit = Integer.parseInt(upperlimit1);

        Random random = new Random();
        randumnum = random.nextInt(ulimit - llimit + 1) + llimit;

        }
OnClickListener input = new OnClickListener() {
        @Override
        public void onClick(View v) {



            if (llimit <= randumnum) {
                limit.setText("Too low");
                number.setText("");
                count = +1;

            } else if (llimit >= randumnum) {
                limit.setText("Too high");
                number.setText("");
                count = +1;
            } else {
                count = +1;
                limit.setText("You got the number after" + count + "tries");

            }

        }

    };
}