randが見つからないエラーが起こりました。
どうすればいいですか?
package com.lifeistech.android.tapnumbers;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
int[] hairetu; String mondai; int seikai; TextView textView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView = (TextView) findViewById(R.id.textView); start(); } public void number1(View v){ if(hairetu[seikai] == 1){ mondai = mondai.substring(1); textView.setText(mondai); seikai = seikai + 1; if(seikai == 4){ start(); } }else{ Toast.makeText(this,"数字が違うよ!!",Toast.LENGTH_SHORT).show(); } } public void number2(View v){ if(hairetu[seikai] == 2){ mondai = mondai.substring(1); textView.setText(mondai); seikai = seikai + 1; if(seikai == 4){ start(); } }else{ Toast.makeText(this,"数字が違うよ!!",Toast.LENGTH_SHORT).show(); } } public void number3(View v){ if(hairetu[seikai] == 3){ mondai = mondai.substring(1); textView.setText(mondai); seikai = seikai + 1; if(seikai == 4){ start(); } }else{ Toast.makeText(this,"数字が違うよ!!",Toast.LENGTH_SHORT).show(); } } public void number4(View v){ if(hairetu[seikai] == 4){ mondai = mondai.substring(1); textView.setText(mondai); seikai = seikai + 1; if(seikai == 4){ start(); } }else{ Toast.makeText(this,"数字が違うよ!!",Toast.LENGTH_SHORT).show(); } } public void start() { hairetu = new int[4]; hairetu[0] = rand.nextInt(4) + 1; hairetu[1] = rand.nextInt(4) + 1; hairetu[2] = rand.nextInt(4) + 1; hairetu[3] = rand.nextInt(4) + 1; mondai = Integer.toString(hairetu[0]) + Integer.toString(hairetu[1]) + Integer.toString(hairetu[2]) + Integer.toString(hairetu[3]); textView.setText(mondai); seikai = 0; }
}
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