The String class represents a string of characters. A String object is created by the Java compiler whenever it encounters a string in doublequotes--this method of creation is usually simpler than using a constructor. A number of the methods of this class provide useful string manipulation functions. length() returns the number of characters in a string. charAt() extracts a character from a string. compareTo() compares two strings. equalsIgnoreCase() tests string for equality, ignoring case. startsWith() and endsWith() compare the start and end of a string to a specified value. indexOf() and lastIndexOf() search forward and backwards in a string for a specified character or substring. substring() returns a substring of a string. replace() creates a new copy of the string with one character replaced by another. toUpperCase() and toLowerCase() convert the case of a string. trim() strips whitespace from the start and end of a string. concat() concatenates two strings, which can also be done with the + operator.
Note that String objects are immutable--there is no setCharAt() method to change the contents. The methods above that return a String do not modify the string they are passed, but instead return a modified copy of the string. Use a StringBuffer if you want to manipulate the contents of a string, or use toCharArray() to convert a string to an array of char values.
The static valueOf() methods convert various Java primitive types to strings.
public final class String extends Object implements Serializable { // Public Constructors public String(); public String(String value); public String(char[] value); public String(char[] value, int offset, int count); # public String(byte[] ascii, int hibyte, int offset, int count); # public String(byte[] ascii, int hibyte); 1.1public String(byte[] bytes, int offset, int length, String enc) throws UnsupportedEncodingException; 1.1public String(byte[] bytes, String enc) throws UnsupportedEncodingException; 1.1public String(byte[] bytes, int offset, int length); 1.1public String(byte[] bytes); public String(StringBuffer buffer); // Class Methods public static String copyValueOf(char[] data, int offset, int count); public static String copyValueOf(char[] data); public static String valueOf(Object obj); public static String valueOf(char[] data); public static String valueOf(char[] data, int offset, int count); public static String valueOf(boolean b); public static String valueOf(char c); public static String valueOf(int i); public static String valueOf(long l); public static String valueOf(float f); public static String valueOf(double d); // Public Instance Methods public char charAt(int index); public int compareTo(String anotherString); public String concat(String str); public boolean endsWith(String suffix); public boolean equals(Object anObject); // Overrides Object public boolean equalsIgnoreCase(String anotherString); # public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin); 1.1public byte[] getBytes(String enc) throws UnsupportedEncodingException; 1.1public byte[] getBytes(); public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin); public int hashCode(); // Overrides Object public int indexOf(int ch); public int indexOf(int ch, int fromIndex); public int indexOf(String str); public int indexOf(String str, int fromIndex); public native String intern(); public int lastIndexOf(int ch); public int lastIndexOf(int ch, int fromIndex); public int lastIndexOf(String str); public int lastIndexOf(String str, int fromIndex); public int length(); public boolean regionMatches(int toffset, String other, int ooffset, int len); public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len); public String replace(char oldChar, char newChar); public boolean startsWith(String prefix, int toffset); public boolean startsWith(String prefix); public String substring(int beginIndex); public String substring(int beginIndex, int endIndex); public char[] toCharArray(); 1.1public String toLowerCase(Locale locale); public String toLowerCase(); public String toString(); // Overrides Object 1.1public String toUpperCase(Locale locale); public String toUpperCase(); public String trim(); }
Many methods
Many methods
BorderLayout.CENTER, BorderLayout.EAST, BorderLayout.NORTH, BorderLayout.SOUTH, BorderLayout.WEST, File.pathSeparator, File.separator, Font.name, HttpURLConnection.method, HttpURLConnection.responseMessage, InvalidClassException.classname, StreamTokenizer.sval, StringBufferInputStream.buffer