在MainActivity.java文件中向哈希密码添加代码的位置

Question

I have to create an Activity that fetches Username and Password from the User. Then it applies an MD5 hash to the Password and finally queries the local database to return "true" or "false".

I got the MD5 code snippet from a blog . The code snippet is showing the following errors on eclipse:

Marked line 1: Multiple markers at this line

• Syntax error on token(s), misplaced construct(s)
• Syntax error, insert "enum Identifier" to complete EnumHeader
• Syntax error on token "String", @ expected
• Syntax error on token "String", @ expected

Marked line 2: Syntax error on token(s), misplaced construct(s)

Marked line 3: Syntax error on token(s), misplaced construct(s)

Marked line 4: Multiple markers at this line

• Syntax error on token "catch", Identifier expected
• Syntax error on token "}", { expected after this token

I am extremely new to java and also the Android environment. Please tell me what is wrong with the code and where should I place the code for the md5 hashing function for my activity to work. Also please guide me towards quering a local SQLite Database and returning required values from there.

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

private String md5(String in) {  //line 1
    MessageDigest digest;        //line 2
    try {                        //line 3
        digest = MessageDisgest.getInstance("MD5");
        digest.reset();
        digest.update(in.getBytes());
        byte[] a = digest.digest();
        int len = a.length;
        StringBuilder sb = new StringBuilder(len << 1);
        for(int i=0;i<len;i++) {
            sb.append(Character.forDigit((a[i] & 0xf0) >> 4, 16));
            sb.append(Character.forDigit(a[i] & 0x0f, 16));
        }
        return sb.toString();
    } catch (NoSuchAlgorithmException e) { e.printStackTrace();} //line 4
    return null;

}

public class MainActivity extends Activity {

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



    Button btn = (Button) findViewById(R.id.button1);
    btn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            EditText text = (EditText)findViewById(R.id.editText1);
            EditText text1 = (EditText)findViewById(R.id.editText2);
            String userid = text.getText().toString();
            String pass = text1.getText().toString();
        Toast.makeText(MainActivity.this,"Entered"+userid+"and password entered is"+pass,Toast.LENGTH_SHORT).show();
        }

    });

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

}

Answer 1

In Java, all methods must exist inside a class.

public class MainActivity extends Activity {
    private String md5(String in) {
        // etc
    }

    // Rest of class
}

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I am extremely new to java and also the android environment.

You will find many benefits from reading a tutorial or introduction, like Learning the Java Language from the language's authors.